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Ph.D .Disser tation Amay a Mar tínez Gracia Octubre2009 Advisor s: J avierUcheMarcuello AntonioV aleroCapilla De par tmentof Mec hanicalEngineering Uni v ersityof Zarag oza EXER GYCOSTASSESSMENTOFW ATERRESOUR CES: PHY SICALHIDR ONOMICS Edif. Agustín de Betancourt . María de Luna, s/n – 50018 - ZA RAGOZA (España) – Teléfono: (+34) 976 76 19 13 – Fax: (+34) 976 76 26 70 http://ingmecani ca.unizar.es - e-mail: sed5 [email protected] DPTO. DE INGENIERÍA MECÁNICA Campus Río Ebro Universidad de Zaragoza Javier Uche Marcuello, Professor of the Depa rtment of Mechanical Engineering of the University of Zaragoza, and Antonio Valero Capilla, Chair of the Department of Mechanical Engineering of the University of Zaragoza CERTIFIE: that the Ph.D. Dissertation “Exergy cost a ssessment of water re sources: Physical Hydronomics” has been developed under th eir supervision by the Ph.D. candidate Amaya Martínez Gracia. Zaragoza, October 2009 Javier Uche Marcuello Antonio Valero Capilla Exergy cost assessment of wate r resources: Physical Hydronomics Amaya Martínez Gracia Dissertation presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy University of Zaragoza, Spain Abstract Human development and its sustainability unco nditionally rely on water. Water as a resource is essential for all daily human activi ties and it can be nowadays considered as a resource even more valuable than oil. The Georgescu-Roegen’s statements a bout the connexion between the Economy and the Thermodynamics, together with the Eco- integ rator approach introduced by Naredo after analyzing the water cost definitions given in the European Water Framework Directive (WFD), and the theory of the th ermoeconomic cost proposed by Valero, are the outline backgrounds of the work presented in this study. Assuming that the physical laws are called to be the objective and universal tools to assess water costs, Physical Hydronomics (PH) has been developed as the accounting tool for the WFD application. PH is defined as the specific application of the Thermodynamics to physically characteriz e the degradation and correcti on of water bodies. The Second Law of Thermodynamics, th rough the exergy loss calculation, is the basic working tool in this study. The final objective of PH is to use those calculated physical costs as a guide to allocate the environmental and resource costs proposed by the WFD by 2015. In this dissertation, the general framework, the foundations, and the accounting principles of PH are developed. Firstly, WFD was carefully studied an interpreted from a Thermodynamics perspective. The different water costs defined in the Directive were translated into exergy concepts and the study hypothesis was established. The diverse river statuses proposed by the Directive were de fined in exergy terms by means of their quantity and quality characterization. S econdl y, from the quantity and quality measurements in the river (they give the exergy value to water bodies), the exergy profiles of the river at different statuses (t hose defined by the WFD) are obtained. Then, the environmental cost of water is obtained (i n energy units) as the exergy needed to cover the gap between the current state of the river and the objective state defined b y the applicable legislation to fulfil the European requirements. To do it, the thermodynamic efficiency of water treatm ent technologies was introduced in the analysis. In the last step, the water costs, ca lculated in energy units, are converted in economic units by introducing the energy price. Moreover, Physical Hydronomics presents an important advantage in relation to other approaches: costs can be allocated according to the degradation (exergy costs) provoked by the different water users in the water bod ies. The Polluter Pays Principle stated by the WFD can be therefore implemented. In addition to that, PH overcomes the proposal by defining the Degrader Pays Principle, which joins the quantitative and qualitative water degradation of water within the analysis. To illustrate the application of the P H method ology, two case studies were developed: the Muga and the Foix watersheds, both located in the Inland Basins of Catalonia, but with quite different characteristics features. The results show that similar results to conventional Measurements Plans to fulfil the WFD objectives are obtained. However, the cost allocation can be performed within this methodology attending to an objective measurement, the water d egradation due to each water use. The last part of this dissertation is devoted to a methodology different from the PH: the emergy approach. The WFD costs are define d according to the emergy basis and the hypothetical real price of water is obtained. In this case, there is not any projection to 2015, just an evaluation of the current situation of the Foix watershed, which is the river basin selected to show the methodology. A mis abuelas Por vuestro tesón, vuestro am or y vuestra generosidad infinita. Exergy cost assessment of water reso urces: Physical Hydronomics i AGRADECIMIENTOS Tengo que reconocer mi difi cultad para modificar los círculos concéntricos en los q ue mi cabeza parece estar organi zada. Algunos av ances voy haci endo, poco a poco. Es evidente pues que en este moment o, al mirar hacia atrás y repasar l os últimos años, el plano pe rsonal y el profesional, las personas y los sentimientos, se mez clan irr emediableme nte. Tras el tra bajo desarrollado, l os titubeos inici ales, la enorme o portunidad que s e presentó al centrar mi trabaj o en el mundo del agua, las miles de vueltas a cada uno de los capítul os y los intensos moment os vividos, es tiempo ahora de realizar esta pequeña reflexión. Quis iera resumir en unos pocos pá rrafos las aportaciones, transmision es, sensaciones compartidas y enriquecimiento que he r ecibido de muchas personas a l o largo de estos años. Comenzaré por mis directores, Javier y Antonio que han sido actores fundamentales en est a historia. A Antonio le agradec eré siempre su insistencia en obten er respuesta a esa pregunta tan suya referida a qué quiere uno s er de mayor. La opor tunidad que me dio de entrar a formar parte CIRCE ha sido fundam ental para tra bajar en la res puesta y ahora, v arios años después, p arece que ésta va tomando form a. También su visión global y su capacidad de dar con la pregun ta exacta par a ampliar y enriquecer muchos as pec tos de la tesis. Gracias Antonio. J a v i e r h a s i d o m i g u í a c o n s t a n t e , u n a p o y o firme y un director excepcional. Me ha proporcionad o una visión treme ndamente rica en tema s hídricos y ha hec ho que sacase lo mejor de mí durante estos añ os. Hemos co mpartido reuni ones, proyec tos e ilusiones pr ofesionales muy estimulantes. Siempre me ha animado cuan do l os resultados nos contrariaba n, me ha estimulado para buscar caminos alternativos y no me ha permitid o ceder al desasosiego, ni siquiera en los momentos más complicados. Gracia s Javi er por todo esto. Me siento afor tunada de que nuestros caminos se cruzasen. La osadía, necesidad más bien, de querer inclui r en este trabaj o aspectos específicos d e disciplinas que no son l a propia, me ha hecho recu rrir a un buen nú mero de profesio nales. Todos ellos se han pr eocupado y me ha n atendido perfectam ente. Graci as a ellos he termin ado con éxito aspectos que inic ialmente veía oscuros. En particular, quiero agradecer al Profesor Germán Badía, de Métodos Estadísticos , su ases oramiento en el desarrollo de los ejemplos sobre eco-exergía presentad os en el capítulo 4; a la Profesora Cleme n Rodellar por sus lecciones magistrales impr ovisadas en el labora torio de gené tic a animal; al Profes or Juan Ignacio P ardo, por su inestimabl e ayuda con la co rrecta caract erización de los iones disueltos en el agua. También quiero ag radecerle a Dani su ayuda con el G IS; a Begoña, su asesor amiento con l a simulación de sistemas para la aplicación dinámi ca de la emergí a; y a Alicia, su apoyo con la definición del ambi ente de referenci a a partir de los trabajos a nteriores. El Profesor Mark Br own y el Profesor Sergio Ulgia ti han sido durante estos a ños un referente constante. Mi estan cia en Florida me ilust ró mucho par a entender corre ctamente las interacciones en los ecosist emas y me pr oporcionó l a base para c omprender l a aproximación emergética que luego seguiría desarroll ando en Siena con el Profesor Ulgiati. Gracias Mark y gracias Sergio por vuestro acogimie nto. A vosotr os, y a vuestr os equipos, porque hab éis conseguido crear un os grupos de trabajo envidiabl es, con grandes pr ofesionales, en los que he trabajado y m e he sentido muy a gusto. Gracias p or integrarme tan amable mente durante mi s Exergy cost assessment of water reso urces: Physical Hydronomics v iii a. Reference environment: sea wate r with organic matter (CONC).............................. 147 b. Reference environment withou t org anic matter (COMP). ......................................... 147 4.2.2.2. Pure water ............................................................................................................ .......... 148 4.2.2.3. Effect of the salts, organic matter and nitrates concentration. ............................. 149 Surface water analysis – salts variati on ............................................................................... 150 Seawater analysis – salts variation ....................................................................................... 153 Surface water analysis – Nitrates, P hosph ates and Organic Matter variation .............. 156 4.2.2.4. Characterization of the chosen Reference Environment ....................................... 158 4.2.3. Exergy of organic matter i n water bodies.......................................................................... 159 4.2.4. Biological exergy component. Ec o-exergy. ....................................................................... 163 4.2.4.1. Eco-Exergy definition ................................................................................................. . 164 4.2.4.2. Eco-Exergy calculation fo r organic matter and organism. ..................................... 166 4.2.4.3. Eco-exergy calculation examples ................................................................................ 167 House made of bricks. .......................................................................................................... 167 130-pages book ................................................................................................................. ..... 168 Crystal lattice structure ...................................................................................................... ... 169 Living organism ................................................................................................................ ..... 170 Summary of the results of the ex amples ............................................................................ 171 4.2.5. Total exergy of a given water body, water mass or water flow ...................................... 172 4.3. Exergy Cost ............................................................................................................... ..................... 173 4.3.1. Historical overvi ew ..................................................................................................... .......... 173 4.3.2. Exergy cost background .................................................................................................. ..... 174 Minimum Exergy Cost.......................................................................................................... 17 7 Unit Exergy Cost (k * ) ............................................................................................................ 177 Specific Exergy Replacement (R estoration) Cos t (SERC) .............................................. 177 Exergy Replacement (Resto ration) Cost (ERC) ............................................................... 177 4.3.3. Exergy cost of the process and exergy cost of the product ........................................... 178 4.3.4. Exergy cost of pumping .................................................................................................. ..... 178 4.3.5. Exergy cost of desalination technol ogies .......................................................................... 178 4.3.5.1. Exergy content in the brine ......................................................................................... 18 0 4.4. Exergy value of the hydrologic cycle ...................................................................................... ... 181 4.4.1. Methodology ............................................................................................................. ............. 182 4.4.1.1. Exergy required to restore the potential exergy component ................................. 182 4.4.1.2. Exergy required to restore the chemical exergy component ................................. 185 4.4.2. Exergy Replacement Cost of worldwide water resources ............................................... 186 4.4.2.1. Exergy cost assessment of the an nual renewable fresh water resources. ............ 186 4.4.2.2. Exergy cost assessment of annu al world water withdraw al ................................... 187 4.4.2.3. Use of solar energy to restore the annual w ater withdrawal .................................. 188 PV systems to restore fresh water ....................................................................................... 188 PTC systems to res tore fresh water .................................................................................... 189 4.5. Exergy value of ice caps and glaciers. .................................................................................... .... 190 4.5.1. Exergy replacement cost of the world ice sheets and glaciers ....................................... 192 4.6. Summary of the chapter .................................................................................................... ........... 194 Chapter 5. Exergy assessment in a wat er course: Physical Hydronomics ....................197 5.1. Introduction. Physical Hydronomics definition. ...................................................................... 198 5.2. The area of study: a waters hed........................................................................................... ........ 199 5.3. Exergy of different types of water ........................................................................................ ...... 199 5.4. Exergy of a river ......................................................................................................... ................... 200 5.4.1. Exergy profile of a river ............................................................................................... ........ 200 5.5. Environmental and Maintenance Flows .................................................................................... 203 5.5.1. Environmental flow methodol ogies ................................................................................... 204 5.5.1.1. Hydrological Methods ........................................................................................... 204 5.5.1.2. Hydraulic rating....................................................................................................... 204 5.5.1.3. Habitat simulation .................................................................................................. 205 Exergy cost assessment of water reso urces: Physical Hydronomics ix 5.5.1.4. Holistic methods ..................................................................................................... 206 5.5.1.5. Comparison of environmental flow assessment methodologies .................... 206 5.6. Reference water bodies .................................................................................................... ............ 207 5.7. Definition of the statuses of the river according the WFD. .................................................. 207 5.7.1. States characteriz ation: ................................................................................................ ......... 212 5.8. Costs definition .......................................................................................................... ................... 214 5.8.1. Definition of WFD’s costs in exergy terms. ..................................................................... 214 5.8.2. Quantity and Quality components of the exergy gap ...................................................... 216 5.9. Calculation procedure. .................................................................................................... .............. 217 5.9.1. Calculation example ..................................................................................................... ......... 219 5.9.1.1. Potential and inorganic matter com ponents ...................................................... 219 a. Environmental Cost cal culation (from FS to OS)........................................................ 220 b. Service Cost calcul ation (from ES to PS) ...................................................................... 226 c. Remaining Resource Cos t calculation (f rom OS to NS) ............................................. 227 5.9.1.2. Organic Matter component .................................................................................. 228 a. Environmental Cost cal culation (from FS to OS)........................................................ 228 b. Service Cost calcul ation (from ES to PS) ...................................................................... 229 c. Remaining Resource Cos t calculation (f rom OS to NS) ............................................. 230 5.9.1.3. Summary of results ................................................................................................. 231 5.9.2. Cost calculation. Ex cel sheets organization. ..................................................................... 231 5.10. Sign analysis for water costs ............................................................................................ .......... 232 5.10.1. Sign analysis for the Service Cost ..................................................................................... 233 5.10.2. Sign analysis for the Environmental Cost ....................................................................... 234 5.10.3. Sign analysis for the Remaining Resource Cos t ............................................................. 235 5.10.4. Interpretation of the water cost sign s from the Thermoec onomics perspective. River indices definition. ............................................................................................................ ................. 235 5.11. Water quality modelling-Riv er basin simulators .................................................................... 237 5.11.1. The necessity of a pressure-im pacts model ..................................................................... 237 5.11.2. Available pressure-impact softw ares (Water Quality Models) ..................................... 238 5.11.2.1. AQUATOOL ..................................................................................................... 238 GESCAL ......................................................................................................................... ........ 239 5.11.2.2. SWAT .................................................................................................................. 239 5.11.2.3. WEAP ................................................................................................................. 240 5.11.3. Description of the chosen pr essure-impacts model: Qual2Kw ................................... 242 5.12. Exergy degradation by diverse uses ....................................................................................... .. 243 5.13. Relationship between the IRC and the degrad ation due to water uses. ............................. 245 5.13.1. Study of the differ e nt water use cases .............................................................................. 246 5.13.1.1. Catchment and return in different river reaches .......................................... 247 a. Potential component ......................................................................................................... 250 b. Inorganic matter component .......................................................................................... 251 c. Organic matter com ponent .............................................................................................. 251 5.13.1.2. Flow input from a different source, after being used. ................................. 252 a. Potential component ......................................................................................................... 254 b. Inorganic matter component .......................................................................................... 254 c. Organic matter com ponent .............................................................................................. 255 5.13.1.3. Catchment in the riv er and return (after us ed) to a different wat ershed .. 256 a. Potential component ......................................................................................................... 257 b. Inorganic matter component .......................................................................................... 257 c. Organic matter com ponent .............................................................................................. 259 5.13.1.4. Several water uses along the river flow. ......................................................... 259 a. Potential component ......................................................................................................... 261 b. Inorganic matter component .......................................................................................... 262 c. Organic matter com ponent .............................................................................................. 263 5.13.1.5. Summary of results and validity of the initial hypothesis. ........................... 264 5.13.2. Water costs allocation among the different water users. .............................................. 265 Exergy cost assessment of water reso urces: Physical Hydronomics x 5.14. Physical Hydronomics and the WFD ...................................................................................... 266 5.15. Exergy cost .............................................................................................................. ..................... 267 5.15.1. Exergy cost of WTP ..................................................................................................... ...... 269 5.15.1.1. Flows analysis ..................................................................................................... 271 Chemical compounds ........................................................................................................... 27 3 Sand ........................................................................................................................... .............. 273 Organic matter ................................................................................................................. ...... 274 Fat ............................................................................................................................ ................ 275 5.15.1.2. Unit exergy cost in WTPs ................................................................................ 276 5.16. Summary of the chapter ................................................................................................... .......... 277 Chapter 6. Application of Physical Hydr onomics ........................................................ 279 6.1. Introduction .............................................................................................................. ..................... 280 6.1.1. Current recovery w ater costs and water imbalance ......................................................... 281 6.1.2. Two well-defined areas .................................................................................................. ....... 282 6.2. WFD in Catalonia: a long and visionary project ...................................................................... 283 6.2.1. Catalan Inland Basins (IBC) charac terization ................................................................... 285 6.2.1.1 Surface Water .......................................................................................................... 286 6.2.1.2 Deep water masses ................................................................................................. 289 6.2.2. Reference water bodies in Catal onia .................................................................................. 290 6.2.3. Maintenance Flows in Catalonia. ........................................................................................ 2 92 6.2.3.1 Ecological flow definition ..................................................................................... 293 6.2.3.2 Procedure to determine the maintenan ce flow in the Rivers network of the IBC .............................................................................................................................. ..... 296 6.2.4. Real quality valu es ..................................................................................................... ............ 297 6.2.5. Geographic characte rizati on: GIS and LDM .................................................................... 297 6.2.6. General aspects about w ater demand in Catalonia .......................................................... 298 6.2.7. Economic characterization of water use and trend analysis ........................................... 301 6.3. Case studies: PH’s procedure fo r the Muga and the Foix Watersheds. ............................... 304 6.4. Case study 1: Muga Basi n .................................................................................................. .......... 305 6.4.1. Muga Basin: physical description ........................................................................................ 305 6.4.1.1 Water availability in the Mu ga Basin ................................................................... 307 6.4.1.2 Main water uses in the Muga Basin ..................................................................... 308 6.4.2. Application of the pressure-imp acts model to the Muga Watershed. .......................... 309 6.4.2.1 Identification and sliceage ..................................................................................... 310 6.4.2.2 Headwaters characterizati on ................................................................................. 311 6.4.2.3 Description of the anthropic pressures in the watershed ................................ 311 Agricultural uses. ............................................................................................................. ....... 312 Urban uses ..................................................................................................................... ......... 314 Muga Dam ....................................................................................................................... ....... 315 6.4.2.4 Diffuse sources ....................................................................................................... 3 15 6.4.2.5 Quality data ........................................................................................................... ... 316 6.4.2.6 Calibration ............................................................................................................ ... 317 6.4.3. Results of Physical Hydronomics in the Muga Watershed ............................................. 318 6.4.3.1 Global exergy value of the Muga watershed ...................................................... 319 6.4.3.2 Exergy profiles in the Muga watershed ............................................................... 320 6.4.3.3 Exergy costs assessmen t in the Muga watershed .............................................. 328 6.4.3.4 Service Cost in the Muga waters hed .................................................................... 332 6.4.3.5 Environmental Cost in the Muga watershed ...................................................... 332 6.4.3.6 Remaining Resource Cost in the Muga w atershed ............................................ 333 6.4.3.7 Economic cost of water in the Muga Watershed .............................................. 333 6.4.3.8 Cost distribution among water users ................................................................... 334 6.4.3.9 Sensitivity analysis of the results .......................................................................... 339 6.4.4. Results comparison w ith previous studies......................................................................... 341 6.5. Case study 2: Foix Basin .................................................................................................. ............ 342 Exergy cost assessment of water reso urces: Physical Hydronomics xi 6.5.1. Foix Basin: physical description. ....................................................................................... .. 342 6.5.1.1 Water availability in the F oix Basin ..................................................................... 343 6.5.1.2 Main water uses in the Foix Basi n ....................................................................... 344 6.5.2. Application of the pressure-imp acts model to the Foix Watershed ............................. 344 6.5.2.1 Identification and sliceage ..................................................................................... 346 6.5.2.2 Headwaters characterizati on ................................................................................. 346 6.5.2.3 Description of the anthropic pressures in the watershed ................................ 347 Agricultural uses .............................................................................................................. ....... 347 Urban uses ..................................................................................................................... ......... 348 Foix Dam ....................................................................................................................... ......... 349 6.5.2.4 Diffuses sources ...................................................................................................... 3 50 6.5.2.5 Quality data ........................................................................................................... ... 351 6.5.2.6 Calibration ............................................................................................................ ... 351 6.5.3. Results of Physical Hydronomics in the F oix Watershed ............................................... 351 6.5.3.1 Global exergy value of the Foix watershed ........................................................ 352 6.5.3.2 Exergy profiles in the Foix watershed ................................................................. 353 6.5.3.3 Exergy cost assesment in the Foix watershed .................................................... 358 6.5.3.4 Service Cost in the Foix watershed ...................................................................... 363 6.5.3.5 Environmental Cost in the Foix waters hed ....................................................... 363 6.5.3.6 Remaining Resource Cost in the F oix watershed .............................................. 363 6.5.3.7 Economic cost of water in the Foix watershed ................................................. 363 6.5.3.8 Cost distribution among the water users ............................................................ 364 6.5.3.9 Sensitivity analysis of the results .......................................................................... 368 6.5.4. Results comparison w ith previous studies......................................................................... 370 6.6. Summary of the chapter. ................................................................................................... ........... 371 Chapter 7. Alternative assessment of the wat er Environmental Cost thro ugh the Emergy approach ....................................................................................................................... 373 7.1. Introduction to Emergy Accou nting ......................................................................................... 374 7.1.1. Hierarchy ............................................................................................................... ................. 375 7.1.2. Basic definitions ....................................................................................................... .............. 376 7.2. Emergy values of natural capital .......................................................................................... ....... 377 7.3. Emergy Algebra ............................................................................................................ ................. 377 7.3.1. Differential bases of emergy algebra .................................................................................. 37 8 7.4. Emergy and water .......................................................................................................... ............... 380 7.5. Steady State Emergy Accounting ............................................................................................ .... 382 7.5.1. Distribution and emergy values of global water storages ............................................... 382 7.5.2. Distribution and emergy values of global water fl ows .................................................... 384 7.6. Dynamic Emergy Accounting. ................................................................................................ .... 385 7.6.1. Some basic ideas for watersheds simulation ..................................................................... 386 7.7. WFD from an emergy perspective ............................................................................................ . 387 7.7.1. Water costs definitions from the emergy approach ......................................................... 387 7.7.1.1. Financial Cost ........................................................................................................ .. 388 7.7.1.2. Resource Cost ......................................................................................................... 388 7.7.1.3. Environmental Cost ............................................................................................... 392 EC assessment through the land uses ................................................................................ 392 EC assessment through the GEmP .................................................................................... 393 7.7.2. Converting Emergy to Monetary Equivalents .................................................................. 393 7.8. Case study: Foix watershed ................................................................................................ ......... 394 7.8.1. Evaluation of Financial Value of Foix Water Res ources. ............................................... 395 7.8.2. Emergy Evaluation of the Reso urce Value of Foix Water Res ources .......................... 395 7.8.3. Environmental Value of Foix Water Resources ............................................................... 398 7.8.4. Summary: Full Cost Recovery of Foix Water Res ources. ............................................... 400 7.8.5. Concluding remarks ...................................................................................................... ........ 400 Exergy cost assessment of water reso urces: Physical Hydronomics xii 7.9. Summary of the chapter ……………………… ………………………… …… ¡Error! Marcador no definido. 401 Chapter 8. Synthesis, Contributi ons and Perspectives ……………………………...…403 8.1. Synthesis ................................................................................................................. ........................ 403 8.2. Summary ................................................................................................................... ...................... 404 8.2.1. Considerations about the r esults ........................................................................................ . 408 8.3. Contributions ............................................................................................................. .................... 410 8.4. Perspectives and future developments ...................................................................................... 415 Annex A. Re sults ...........................................................................................................419 A.1. Muga map .................................................................................................................. .................... 420 A.2. Flows in the Muga rive r ................................................................................................... ........... 421 A.3. Global exergy value of the Muga w atershed ............................................................................ 425 A.4. Exergy profiles for the Muga River ........................................................................................ ... 426 A.4.1. Exergy profile of the PS in the Muga river ...................................................................... 426 A.4.1.1. March ................................................................................................................. ............ 426 A.4.1.2. July .................................................................................................................. ................ 427 A.4.1.3. September ............................................................................................................. ........ 428 A.4.2. Exergy profiles (PS, ES and OS) in the Muga river ........................................................ 429 A.4.2.1. March ................................................................................................................. ............ 429 A.4.2.2. July .................................................................................................................. ................ 430 A.4.2.3. September ............................................................................................................. ........ 431 A.5. Foix map .................................................................................................................. ...................... 433 A.6. Flows in the Foix river ................................................................................................... ............. 434 A.7. Global exergy value of the F oix watershed .............................................................................. 438 A.8. Exergy profiles for the Foix River ........................................................................................ ..... 439 A.8.1. Exergy profile of the PS in the Foix River ....................................................................... 439 A.8.1.1. March ................................................................................................................. ............ 439 A.8.1.2. July .................................................................................................................. ................ 440 A.8.1.3. September ............................................................................................................. ........ 441 A.8.2. Exergy profiles (PS, ES and OS) in the Foix river .......................................................... 442 A.8.2.1. March ................................................................................................................. ............ 442 A.8.2.2. July .................................................................................................................. ................ 443 A.8.2.3. September ............................................................................................................. ........ 444 Annex B. Chemic al exergy .......................................................................................... 447 B.1. General water exergy equation ............................................................................................. ...... 448 B.2. Eco-exergy ................................................................................................................ ..................... 449 B.2.1. Exergy and informati on theory .......................................................................................... 4 50 B.2.2. Defini tion of eco-ex ergy ................................................................................................ ...... 451 B.2.3. Basic problema: c io measurement. ...................................................................................... 452 B.3. Minimum energy requ ired for desalination. ............................................................................. 455 B.4. Calculation methodol ogy: standard chem ical exergy of the chemical elements ................. 456 B.4.1. Standard Chemicals exer gy of Chemical s compounds ................................................... 457 B.4.2. Gaseous reference su bstances ............................................................................................ 458 B.4.3. Solid reference substances .............................................................................................. ..... 458 B.4.4. Reference substances dissolved in seawater ..................................................................... 458 Annex C. Water Fram ework Dir ective .........................................................................461 C.1. General contents of the Wate r Framework Directive (2000/60/EC) ................................. 462 C.2. Water-related organizations ............................................................................................... ......... 466 C.2.1. International water- related organizations ......................................................................... 466 C.2.1.1. United Nations Or ganisation for Education, Scienc e and Culture (UNESCO) 466 C.2.1.2. The international netw ork of basin organisations (INBO ) ................................... 467 Exergy cost assessment of water reso urces: Physical Hydronomics xiii C.2.1.3. Global Water Partnership (GWP) ............................................................................. 468 C.2.1.4. World Water Council (WWC) .................................................................................... 468 C.2.1.5. The World Bank. ....................................................................................................... ... 469 C.2.1.6. The International Water Manag ement Institute (IWMI) ....................................... 469 C.2.1.7. World Resources Institute (W RI) .............................................................................. 470 C.2.1.8. The Stockhol m International Water Institute (SIWI) ............................................ 470 C.2.2. National water-re lated organizations ................................................................................. 471 C.2.2.1. Fundación Nueva Cultura del A gua (FNCA) .......................................................... 471 C.2.2.2. Coordinadora de Afect ados por Grandes Embalses y Tr asvases (COAGRET).471 C.2.2.3. Instituto Tecnol ógico del Agua (ITA ) – Universidad Politéc nica de Valencia .. 471 C.3. Spanish water acco unts methodolog y ....................................................................................... 4 71 C.3.1. Spanish water accounts: quantity ....................................................................................... 4 71 C.3.1.1. Total Resources and Gross Annual Availability ..................................................... 472 C.3.1.2. Total uses an d Net Accumulation ............................................................................. 473 C.3.1.3. Example: Inland Basins of Catal onia ........................................................................ 474 C.3.1.4. Spanish water accounts: quality ................................................................................. 479 C.3.1.5. Hydraulic power (HP) ................................................................................................. 4 80 C.3.1.6. Osmotic power (O P) ................................................................................................... 4 81 Annex D. Emergy accounting ...................................................................................... 483 D.1. Transfor mity .............................................................................................................. ................... 484 D.2. Emergy evaluation of the bi osphere and its processes .......................................................... 486 D.2.1. Annual budget of emergy fl ow supporting the Geobiosphere ..................................... 487 D.2.2. Average Emergy Uni t Values for Main Global Processes ............................................. 489 D.3. Emergy evaluation proced ure: Emergy Synthesis .................................................................. 494 D.3.1. Energy Systems Diagram .................................................................................................. .. 495 D.3.2. Emergy Evaluation Table ................................................................................................. .. 495 D.3.3. Procedure for emergy accounting ..................................................................................... 495 D.4. Emergy based indices of sustai nability .................................................................................... . 497 D.4.1. Percent Renewable (%Ren) ................................................................................................ 498 D.4.2. Emergy Yield Ratio (EYR) ................................................................................................ . 498 D.4.3. Environmental Loading Ratio (ELR) ............................................................................... 498 D.4.4. Emergy Sustainablility Index (ESI) ................................................................................... 498 D.4.5. Emergy yield rati o ...................................................................................................... .......... 499 D.4.6. Emergy Investment Ratio (IR) .......................................................................................... 49 9 D.4.7. Empower density ......................................................................................................... ........ 499 D.4.8. Emprice ................................................................................................................. ................ 499 D.4.9. Emergy exchange ratio ................................................................................................... ..... 500 D.4.10. Emergy per capita ...................................................................................................... ........ 500 D.5. Energy Systems symbols.................................................................................................... ......... 500 Annex E. Water simula tion softwares ..........................................................................501 E.1. Water quality models ...................................................................................................... ............. 501 E.1.1. Group 1 ................................................................................................................. ................. 501 E.1.1.1.WASP7 .................................................................................................................. .......... 501 E.1.1.2.QUAL2K ................................................................................................................. ....... 502 E.1.1.3.EPD -RIV1 ............................................................................................................... ...... 502 E.1.1.4.EFDC Hydro ............................................................................................................. .... 503 E.1.1.5.AQUATOX ................................................................................................................ ... 505 E.1.1.6.WAM .................................................................................................................... ........... 505 E.1.1.7.WARMF .................................................................................................................. ....... 507 E.1.1.8.LSPC ................................................................................................................... ............ 508 E.1.2. Group 2. Particular w ater problems contex ts simulation models ................................ 509 E.1.2.1.ADIOS2................................................................................................................. ......... 509 E.1.2.2.GNOME .................................................................................................................. ...... 510 Exergy cost assessment of water reso urces: Physical Hydronomics xi v E.1.2.3.BIOPLUME III ........................................................................................................... . 511 E.1.2.4.SWMM ................................................................................................................... ......... 511 E.1.3. Comparative ............................................................................................................. ............. 512 E.2. Simulation model used in this w ork: Qual2KW ...................................................................... 513 E.2.1. Introduction ............................................................................................................ .............. 514 E.2.2. Segmentation and hydraulics ............................................................................................. . 516 E.2.3. Flow balance ............................................................................................................ .............. 518 E.2.4. Hydraulic characterist ics ............................................................................................... ....... 519 E.2.4.1.Manning Equation ....................................................................................................... . 519 E.2.5. Travel time ............................................................................................................. ................ 521 E.2.6. Longitudinal dispersion ................................................................................................. ...... 522 E.2.7. Temperature model ....................................................................................................... ....... 523 E.2.8. Surfac e heat flux ....................................................................................................... ............ 524 E.2.9. Constituent model ....................................................................................................... ......... 524 E.2.9.1.Constituents and general mass balance ..................................................................... 524 E.2.10. Reaction fundamentals and constituents reactions ....................................................... 527 E.2.11. The genetic algorithm for the cali bration of QUAL2Kw ............................................ 527 E.2.12. Model parameter worksheets ............................................................................................ 5 28 E.2.12.1.Qual 2K input wor ksheets ......................................................................................... 529 E.2.12.2.Headwater worksheet ................................................................................................. 53 1 E.2.12.3.Reach worksheet ....................................................................................................... .. 532 E.2.12.4. Point sources worksheet ........................................................................................... 535 E.2.12.5. Diffuse sources worksheet ....................................................................................... 536 E.2.13. Qual 2K output worksheets .............................................................................................. 537 E.2.13.1. Hydraulics summary worksheet ............................................................................... 537 E.2.13.2. Temperature output worksheet ............................................................................... 538 E.2.13.3. Water quality output worksheet............................................................................... 538 E.2.14. Model Validation ....................................................................................................... ......... 539 Annex F. Technical data………………………………………………………………....544 F.1. Sludge treatment .......................................................................................................... ................. 544 F.1.1. The sludge agricultural use ............................................................................................. ..... 545 F.1.1.1 Sludge aerobic stabilization .......................................................................................... 546 F.1.1.2 Anaerobic digestion ...................................................................................................... 546 F.1.2. Sludge therm al pr ocesses ................................................................................................ ..... 547 F.1.3. Use in industy .......................................................................................................... .............. 547 F.1.4. Disposal ................................................................................................................ .................. 548 F.2. Technical data of s ome WTP in Cataloni a. .............................................................................. 548 F.2.1. WTP Begur ............................................................................................................... ............. 548 F.2.2. WTP Blanes .............................................................................................................. ............. 549 F.2.3. WTP Cadequés ............................................................................................................ .......... 550 F.2.4. WTP Castell d’Aro ....................................................................................................... ......... 550 F.2.5. WTP Colera .............................................................................................................. ............. 551 F.2.6. WTP El Port de la Selva ................................................................................................. ..... 552 F.2.7. WTP Empuriabrava ........................................................................................................ ...... 552 F.2.8. WTP L’Escala ............................................................................................................ ............ 553 F.2.9. WTP Lançà ............................................................................................................... ............. 553 F.2.10. WTP Lloret de mar ...................................................................................................... ....... 554 F.2.11. WTP Palamós ............................................................................................................ .......... 555 F.2.12. WTP Pals ............................................................................................................... ................... 555 Annex G. Resumen. Cálculo de los costes exergéticos del agua: Hidronomía Física . 557 G.1. Síntesis .................................................................................................................. ......................... 558 G.2. Introducción .............................................................................................................. ................... 558 G.2.1. Directiva Europea Marco del Agua .................................................................................. 560 Exergy cost assessment of water reso urces: Physical Hydronomics x v G.2.2. Definición de costes en la DMA. ...................................................................................... 561 G.3. Interpretación de los costes de la DMA desde el enfoque eco-integrator.......................... 562 G.4. Propuesta metodológi ca: Hidronomía Física .......................................................................... 563 G.4.1. Exergía de una masa de agua ............................................................................................. . 564 G.4.1.1. Componente de exergía térmica ...................................................................... 564 G.4.1.2. Componente mecánica de exergía .................................................................. 565 G.4.1.3. Componente de exergía potencial ................................................................... 565 G.4.1.4. Componente de exergía cinética ..................................................................... 565 G.4.1.5. Componente de exergía química ..................................................................... 565 G.4.1.6. Componente de concentración de ex ergía .................................................... 566 G.4.1.7. Ambiente de refe rencia para los análisis de las masas de agua ................... 566 G.4.2. Perfil exergético de un río ............................................................................................. ...... 567 G.4.3. Caracterización de los estados de las masas de agua e implementación práctica....... 568 G.4.4. Definición de los costes de la DM A en términos de exergía ........................................ 569 G.4.5. Componentes de cantidad y calidad en el coste exergético ........................................... 570 G.4.6. Coste exergético ........................................................................................................ ........... 571 G.4.7. Relación entre el I RC y la degradación debida a los usos del agua .............................. 571 G.5. Case study: Muga Basin .................................................................................................... .......... 573 G.6. Resumen y conclusiones .................................................................................................... ......... 574 References ..................................................................................................................... ......................... 575 Nomenclatur e ................................................................................................................... ..................... 599 List of Figures and Tables ..................................................................................................... .............. 605 Chapter 1 Motivation and Justification. Exergy cost a ssessment of water r esources: Physical Hydrono mics 1 Chapter 1 Moti v ation and justification The requirements of the European Water Framework Directive (WFD) regarding the environmental cost of water can be understood as the origin of this dissertation. The necessity of an objective methodology able to connect the Physical reality of water bodies with Economics gave sense to the de velopment of Physical Hydronomics (PH), the thermodynamics-bas ed approach to asse ss water costs, developed an d presented in this work. The WFD as a water management reference is a legal text that arose from a series of different European Union Environmental Action Programs and it integrates different partial Directives aimed at water management. It added a new point regarding the protection of water environments an d resources, using an integrated approach to the natural environment and socio-economic issues. Like all other European Directives, the WFD has to be transferred to the state and regional legislations and instruments are required for its application and to comply wi th the terms imposed by the WFD itself. In Spain, the WFD has been incorporated into the Revised Water Law ( Real Decreto Legislativo 1/2001- de 20de julio, por el que se aprueba el texto refundido de la Ley d e Aguas. ) and into the Instruction of Hydrological Planning ( Orden ARM/2656/200 8 de 10 de septiembre, por la que se aprueba la in strucción de planificación hidrológica. ). The WFD has provided the authorities responsible for water policy with the necessary instruments to fulfil its imposed environm ental objectives. The drawing up of the document IMPRESS (impacts and pressures report) in each area, which defines the bodies of water, pressures, impacts and possible risks of incompliance with the objectives, forms a solid base for the prepar ation of river basin plans. On the other Chapter 1 Motivation and Justification. Exergy cost a ssessment of water r esources: Physical Hydrono mics 8 1.4. W ater and energ y: a v er y close r elationship Because of the interconnection between wa ter an d energy, it is vital to manage them together, rather than in isolation. The energy savings from water conservation and th e water savings from energy efficiency are inextricably linked, and these linkages should be considered when determining the best cour se of action from an economic, social or environmental perspective. A nation’s water and energy resources are inex tricably entwi ned. Energy is needed to pump, treat, transport, heat, cool, and recycle wa ter. On the flip side , the force of falling water turns the turbines that generate hydr oelectric electricity, and most thermal power plants are dependent on water for coo ling (CEC, 2005). The systems of manmade storage, treatment and conveyance structures re quire large amounts of energy to deliver quality water. At the first step, water is diverted, coll ected, or extracted from a source. Then, its transport and eventual water treatment facilit ies are previous to its distribution to end users. What happens during end use primarily depends on the type of us e. Wastewater from urban uses is collected, treated, and discha rged back to the environment, where it becomes a source for someone else. W a t e r S uppl y & C o nv ey a nc e Wa te r Distri bu tio n Wa t e r Tr e a tm e n t R e cy cle d W a t e r t r e at me nt R e cy cl ed W a t e r D is tri b ut ion W a s t ew at er Co l l e c t i on W a s t ew at er Tr ea tm e n t Wa st ew a t er D i s c h arge End - uses: • A gr i cul tur al • R es i d e n ti al • C o mme rc ial • I nd u s tr i a l Sourc e Water Supply & Conv ey ance Water Distributio n Wat er Treatm ent Recy cled Wat er tre atment Recy cled Water Distribution Wastewater Coll ect ion Wastewater Treatmen t Wast ewater Discharge End-uses: • Agricultural • Resi denti al • Co mmercial •I ndustri al Source Figure 1.1. Water use cycle (Source: CEC, 2005) The dynamic give-and-take relationship between water and energy resources is presen t along the whole water cycle (Figure 1.1). Each element of the water use cycle has unique energy intensities, with a considerable variability in both the range of intensities for each segment an d the components of the water use cycle. For the water supply and conveyance, the energy intensity is determined primarily by the volume of water that is transported, the di stance, and the changes in topography along its route. In water treatments, a key factor is the in tended end user and its water quality requirement. Some sources of water need very little treatment, so their energy intensity is low, but some others need much more treatment (e.g., brackish groundwater or Chapter 1 Motivation and Justification. Exergy cost a ssessment of water r esources: Physical Hydrono mics 9 seawater desalination). Regarding water dist ribution, some fresh water distribution systems are gravity fed, but most require some pumping. The primary driver of increased energy for water distribution is urban growth. Wastewater collection also demands energy. Some wastewater collection systems use gravity to bring the wastewater to a treatment plant. Nevertheless, most of them need energy to lift or transfer the wastewater. The same happens for the wastewater discharge. In the wastewater treatment, energy consumption is compulsory, though some require more than others depending on the quality of the waste stream, the level of treatment required, and the treatment technologies used. Finally, the energy needed for the recycled water and distribution depends upon the level of wastewater treatment in existing facilities. The effluent may be recyclable without requiring additional treatment to displace potable water sources used for non- potable applications. More energy is needed if additional treatment is required. The ranges of energy intensities for the me n tioned water-related processes are presented in Table 1.1 Water-Use Cycle Segments Low High Water Supply and Conveyance 0.00 3.70 Water Treatment 0.03 4.23 Water Distribution 0.18 0.32 Wastewater Collection and Treatment 0.29 1.22 Wastewater Disc harge 0.00 0.11 Recycled Water Treatm ent and Distribution 0.11 0.32 Table 1.1. Range of energ y intensity of the water us e cycle. Units: kWh/m 3 . (Source: adapted from CEC, 2005) Energy efficiency in the water and wastewater industry saves money in operations and maintenance costs, reduces capital cost s of new supply, improves solvency and operations capacity of water utilities, improves service coverage, reduces emissions and improves water quality, among a host of ot her related benefits. In order to support larger efforts to reduce energy use in water and wastewater sys tems, larger-scale energy and water management should be entrusted to the local level f or implementation. The term ‘watergy’ efficiency has been coined by the Alliance to Save Energy (2007) to describe the combined water and energy efficiencies which are available to municipalities and water users. The most widely recognized aspect of th e water-energy relationship is hydropower production. Hydroelectricity supplies over 20% of the world’s electricity needs. Countries like Norway, Iceland, Canada and Austria produce well over 70% of their electricity supplies through hydroelectricity (EIA, 2008). Figures on this i ssue will be presented in Chapters 2 and 4. Involvement of the energy utility provides the needed Chapter 1 Motivation and Justification. Exergy cost a ssessment of water r esources: Physical Hydrono mics 10 support for implementing energy efficiency measur es and ensuring that efforts to reduce energy and water waste are sustainable as a business practice. Energy efficiency in any water utility never has a beginni ng or an end. To sustain it s energy savings, a water utility must continue to monitor its energy use and set goals for improvement. In the study presented in this work, the energy needed to restore the quantity and quality in the rivers is a key issue. In this sense, energy efficiency in the proposed water utilities and the minimization of energy resources consumption are crucial. 1.5. The oppor tunity pr esented by the European W ater F ramew ork Directiv e. The European Council Water Framework Di rective came into force on 22 December 2000, establishing a new, integrated appr oach to the protection, improvement and sustainable use of Europe's rivers, lakes, es tuaries, coastal waters and groundwater. This legal text introduces, among numerous novelties, two significant changes related to the way the water environment must be managed across the European Community: the types of environmental objectives to be c onsidered and a river basin management planning system On the one hand, previous European water legislation sets objectives to protect particular uses of the water environment from the effects of pollution and to protect the water environment itself from especially da ngerous chemical substances. T hese types of objectives are taken forward in the Directive’s provisions for Protected Areas and Priority Substances respectively. The Directive also introduces new, broader ecological objectives, designed to protect a nd, where ne cessary, restore the structure and function of aquatic ecosystems themselves, and ther eby safeguard the sustainable use of water resources. Future success in managing Eur ope’s water environment will be mainly judged by the achievement of these ecological goals. Theses objective states for the waters will appear later on in this dissertation (Chapter 5) and will be na med as good ecological state (GES) and high state (HS) . On the other hand, a river basin management planning system is the key mechanism for ensuring the integrated management of: ground water, rivers, canals, lakes, reservoirs, estuaries and other brackish waters, coastal waters, and the water needs of terrestrial ecosystems that depend on groundwater, such as wetlands. The planning system is called to provide the decision-making framework within which costs and benefits can be properly taken into account when setting envi ronmental objectives, and to set out cost- effective combinations of measures to achi eve th e objectives that could be designed and implemented. It will also provide new opportunities for anyone to become actively involved in shaping the management of river basin districts – neighbouring river catchments, together with their associ ated stretches of coastal waters. This second aspect concerning hydrological aspects, presents a new approach in th e treatment of hydrological units, as it defines them according to the Directive’ s objectives. In order to regulate the exploitation of water resources and to prevent the deterioration of its quality by protecting and improving aquatic environments related to it, the Directive establishes deadlines and promotes a sustainable use of the resource. For this reason, the first task of the Di rective obliges Community Member States to Chapter 1 Motivation and Justification. Exergy cost a ssessment of water r esources: Physical Hydrono mics 11 identify and characterise water bodies as the basic hydrological units. They are the basis of the analysis of the characteristics o f ri ver basins, which become the territorial units for management. The purpose of this initia l work consists in making an accurate description of the status of the surface wa ter and groundwater, which can be revised every six years. This description requires specific info rmation and monitoring programmes, and it is the basis for regulating the water use, which will be defined by the River Basin Water Plans. In addition to the two mentioned features, from the point of view of hydrological description, two premises in the understanding and application of the WFD should be also pointed out: Firstly, water is the element being managed. Its availability, always taking into account the quality/quanti ty pairing, is related to special local features of the water cycle, on the natural side, and to current exploitation of the resource, relating to human action. Secondly, the GES of aquatic systems is the main objective of the Directive. It supports a sustainable water use because it can be understood as an indicator of the correct exploitation of water resources, respecting its natural dynamics. Water bodies in a River Basin Distr ict are differentiated according to the mentioned categories (rivers, lakes, wetlands, coastal water, groundwater), and classified under different characteristic-based types (mor phometric, environmental, climatic and geographical, etc). In strong pressurized area s, highly-modified water masses appear, but they do not need to reach the GES because it is n either economically nor socially viable, or the impact of their recovery leads to even wo rse environmental impact. There, the objective is the Good Ecological Potential (GEP), which accounts for their maximum possible quality. 1.5.1. Water uses and their sustainability In spite of the promotion of the sustainable use of water, and based on the protection of water resources, the idea of sustainability is a very diverse one, due to its application in several spheres related to the Envi ronment. The definition of a sustainable exploitation of water given by the Austra lian Department of the Environment and Heritage (DEH, 2004) is that use which, measured in a planning time context, involves acceptable pressure and protects the economic, social and environmental values that depend on it. This definition emphasises that sustainable use must be based on an extraction system and not on a predefined volu me. A system is understood as a set of management measures defined for a river basin and for specific periods in which permitted extraction volumes must be conditioned by the pace of recha rge and the pressures generated on the environment; it allo ws that in exceptiona l, clearly specified circumstances, extraction volumes should change with regard to those fixed in the established planning period. So, achieving an acceptable level of pressure involves recognising that a level of impact is actually acceptable and must be agreed by consensus. This consensus , term cited in the WFD as public participation , will normally have to include environmental, economic and social aspects, and also give time for the en vironment to adapt to a new balance. That is, it involves the integrated management of th e water cycle, both of human n eeds and of the associated ecosystems, but adapted to the overall response of the system (specifically the river basin) depending on the new information and generated needs. In the case of Chapter 1 Motivation and Justification. Exergy cost a ssessment of water r esources: Physical Hydrono mics 12 the Directive, the status of the water bodies will become the indicator to assess the acceptability of the pressure ex ercised on the environment. Any water use gives rise to a reduction in exis ting resources along the time, whatever it was a river flow or an aquifer. Exploitati on that involves an unaccep table reduction in flow or volume stored therefore falls outs ide the definition of sustainable use. For this reason, if levels below the appropriate ones are reached because of extreme seasonal or year-on-year hydrological variations, it m ust be defined whether thi s pressure is acceptable (in order to maintain supply) an d wh ether amendments to the managemen t plans must be adopted. In other words, sustainable management involves a degree of flexibility in the determination of the extra ction systems, controlled by equ ity between generations and a balance between envir onmental aspects and social and economic values (UN-WWAP, 2006). Drawing up river ba sin plans and periodically updating them is the basis of the regulation of exploitation systems. This definition of sustainability recognises that water resources have multiple values – all of them legitimate – from those associated wi th the maintenance of ecosys tems to those generated by supplying human demand, as we ll as their social, cultural or landscape nature, among others. From them, ecological- type values deserve special consideration, as inappropriate exploitation involves the risk of irreversible impacts. A summary of the specific contents of th e WFD can be found in Annex A of this dissertation. 1.5.2. Recent water history in Spain The economic and environmental analysis of water issues in Spain has always been an important research question. Spain is a rela tively large country in the Euro pean Union (EU), with a land surface of 505 958 km 2 (islands included) and an average precipitation around 340,000 hm 3 /year (684 mm), with a substantial spatial and temporal rainfall variation. The water scarcity is especially ac ute in the south-eastern watersheds, triggered by aquifer overexploitation. Looking at the last few years in Spain, the management of water resources involved in the application of the Spanish National Hydrological Plan (SNHP) has generated intens e social involvement and, derived from it, matters concerning water have been the subject of discussion and debate. In this period, the need for water management based on respect for the environment and on the sustainable use of these resources has been taking on overwhelming importance. These valu es currently make up the cores of water policy explicitly declared by the Spanish government. The fact of recognising that nature is proba bly the most important water user provides a different view of water use. The Water Act of 1985, updated in 2001, recognises the importance of the water cycle in the dynami c of natural systems and refers to its protection. However, despite this legal defi nition, the establishment of a sustainable view of water management was not reflected in the Spanish National Hydrological Plan (SNHP) of 2001, which resulted in intense so cial and academic mobilisation leading to its repeal in 2004. This action against the Pl an, which began in the area around the Ebro River, has been the subject of consideration at European level because of the intention to manage a natural resource – water – which is indispensable for human development Chapter 1 Motivation and Justification. Exergy cost a ssessment of water r esources: Physical Hydrono mics 13 and the preservation of the natural environment, in an objective way, involving participation. The SNHP, intended to be the fundamental norm shaping the framewo rk for water management and water quality in Spain, cons isted of two main parts: (1) a new water transfer of 1,050 cubic hectometres per year from the basin of the river Ebro to other river basins in the north, south-east, and sout h of Spain; and (2) of a block of 889 public water works affecting all the Spanish river basi ns which is listed in Appendix 2 of the Law. Obviously, the main project wa s the large water transfer to the Levante and south- eastern regions in order to solve the critical problems of overuse, degradation and scarcity of water resources, consequence of decades of water resource mism anagement (Albiac et al, 2003). Many organisms and institutions claimed agai nst the article 13 of the Law, authorising the transfer Plan. As an example, the World Wide Fund for Nature (WWF) asserts that the Ebro transfer would have a negative e ffect on the areas supplying the water, which already have a much lower socio-economic le vel than the areas which would receive the water. This organism affirmed that the Spanis h government’s analysis hided this reality under three basic errors: not taking into ac count the river basin perspecti ve; offering superficial data for the autonomous communities rather than looking more closely at a local level; and using misleading so cio-economic indicators (WWF, 2004). Aragón and Catalonia , two regions of the basin from wh ich water was to be transferred, strongly opposed the Plan. While Aragón opposed it from the very beginning, Catalonia voted in favour of it in 2001, but later on, in 2003, joined Aragón against the Plan after the regional political party in power was defeated. They argued that the SNHP was conventional, supply-oriented and could not be justified on economic, environmental or social grounds. Furthermore, the water tran sfer was considered to be unnecessary if proper demand management practices wer e implemented in the water-importing regions. In terms of sust ainability, numerous analyses indicated that the environmental and the economic principles were mostly ignored (AG, 2001). Because funding from the European Commission was necessary for the construction of the infrastructure considered within the Plan, the Government of Aragon and several environmental groups complained formally to the European Commission on the magnitudes and distributions of the various negative impacts of the Plan (Tortajada, 2006). A Seminar was organised in 2003 by the European Community (EC) with the objective to promote dialogue between the Spanish and Aragonian Governments an d the environmental groups. In the light of the discussions and the results of the different technical studies, and after considering that the Plan did not address properly economic and environmental concerns, there were seve ral reports within the EC which did n ot recommend the financial support for the im plementation of the SNHP. Nevertheless, before the European Commission could take a final decision, the 2004 elections i n Spain resulted in the change of the ruling po litical party and the cancellation of the 2001 SNHP. For the last years, two important factors are present in water policy: an important delay and the expensive cost of water for the agri cultural sector. Irrigation users mean that they can not afford to pay the real cost of the provided water (L lamas, 2009). Chapter 1 Motivation and Justification. Exergy cost a ssessment of water r esources: Physical Hydrono mics 14 A complete chronology of the Eb ro transfer proposal can be found in Tortajada (2006), as a case study for the 2006 Human Developm ent Report. Albiac et al. (2006) also make an interesting review of this chapter of the Spanish hydrological history. Later on, the Law 11/2005 ( L E Y 1 1 / 2 0 0 5 , d e 2 2 d e j u n i o , p o r l a q u e s e m o d i f i c a l a L e y 10/2001, de 5 de julio, de l Plan Hidrológico Nacional ) was enacted. This law proposed the Programme on Actions for the Management and Use of Water whose objective was to develop and implement appropriate water policie s in full consideration of water quantity and quality issues. The basis for what might be calle d reasonable water management ( new w ater culture ) in Spain can be seen in the texts written by Martínez (1997), Arrojo and Naredo (1997), Llamas et al. (2000), Prat and Munne, (2000), Arrojo (2004), Martínez and Jiménez (2003), Aguilera and Arrojo (2004) and Estevan and Naredo (2004), among many others, in which water is valued not only as a necessity for human use. Instead, its ecological, geodynamic, social and even aesthetic function is recognised and it is considered as a heritage that must be protected and preserved. 1.5.3. The Spanish water authorities and the WFD The autonomous basin management organisations, called Basin Confederations , have existed in Spain since 1926 (first in Europe). For nearly a century, they have demonstrated their efficiency and even serv ed as a model for the European Union in establishing the new river-basin management bodies in the Water Framework Directive, called river basin districts . The creation of the basin confederati ons (the first being that of the Ebro) was initially a response to the principle of decentralisation. It seemed reasonable that the river basin should be the unit for water management. Over time this farsighted idea has become established as an unquestioned certainty in the governance of water resources. The basin confederations (or water agencies , as the management bodies are called when th e autonomous regions have exclusive powers over a particular river basin) have full executive autonomy to carry out their function: hydrological planning in their basin; management of resources and usage; demand management; execution of new hydraulic infrastructures; water policy; protection of waters in the public domain, etc. The implementation of the WFD with the thr eefold aim of satisfying the demand for water, achieving a good ecological status of the bodies of water and taking measures against floods and droughts, has represented a boost for the Spanish bas in confederations. The management of water by water district as established by the WFD has not meant any significant change for the basin confederati ons because of the mentioned long experience. The territorial based water management mo del organised on a pyramidal basis is the basis for achieving river basin management th at cuts across administrative borders. The basin confederations combine the whole of this organisational framework related to water and thus adapt perf ectly to core concepts behind the In tegrated Water Resources Management (IWRM) and WFD, i.e. decentralisation and participation. Chapter 1 Motivation and Justification. Exergy cost a ssessment of water r esources: Physical Hydrono mics 15 In Spain, the water authorities are entities under public law with thei r own legal personality, separate from the State. For administrative purposes they answer at present to the Ministry of the Environment and Rural and Marine Affairs. Under article 21 of the Water Act, the fun ctions of the basin organisations are as follows: - To draw up the Water Basin Plan for th eir basin, including its monitoring and review. - To manage and control the water in the public domain, including flowing surface water, the beds, banks and perimeters of the rivers and lakes, and groundwater. - To manage and control water use in the general interest of the nation or that affecting more than one autonomous region. - To plan, construct and exploit works undertaken using the organisation own funds, as well as those ordered by central Government. - To comply with those functions derived from agreements with the autonomous regions, local corporations and other pub lic or private bodies, or those with private entities. - To perform these functions, basin organisations have been granted the following competences: o Granting authorisations and concessions referring to water in the public domain. Except for those relating to work and actions of general interest to the State, which correspond to the Ministry. o Inspection and monitoring of compliance with the conditions of authorisations and concessions relative to water in the public domain. o Organising forums and hydrological studies on flood risk and the control and quality of water. o Study, planning, construction, preservation and exploitation and improvement of water works included in their own plans, as well as those which they may be charged with. o Defining quality objectives and programmes for water, in accordance with hydrological planning. o Providing technical and advisory services. In consequence, these already assigned attributions help significantly in the WFD implementation. The WFD establishes the environmental quality objectives in rivers as one of the basic pillars for achieving a good ecological stat us by the year 2015. This represents a new challenge for the coordination of the environmental policies of autonomous regions and central government and the basin organisati ons. This coordination involves the power allocation. In terms of participation in water manageme nt, another of the pillars of the European Union water policy, the basin confederations have, since their creation , included a significant degree of representation in their various bodies: the users assemblies, water withdrawal commission, exploitation board s, water council and governing board. Participation by water users in management may be consider ed a model as even the budget of each of the sub basins is particip ated in by the users themselves through the Chapter 1 Motivation and Justification. Exergy cost a ssessment of water r esources: Physical Hydrono mics 16 exploitation boards. The incorporation of ci vil society in general is progressing with active participation in drawing up the river basin plan and the creation of a committee of competent authorities. This active part icipation is a result of the more holistic approach to water management in the 21st century, when environmental factors ar e becoming increasingly important. 1.5.4. The Water Framework Directive (2000/60/EC) in Catalonia The concept of Ecological Status, which is introduced by the regulatory text of the Water Framework Directive, appears as a k ey measurement item for analysis of the quality of water systems and their management, and includes consideration of their state of health (an expression of the structure and operation of ec osystems). This concept appears in Catalan legislation on water (Law 6/1999- de 12 de julio, de Ordenación, Gestión y Tributación del Agua .), and in the amended text of the legislation on water in Catalonia (Legislative Decree 3/2003 of 4 November). In the case of Catalonia, th e d eployment of the regulations falls under the competence of the Catalan Water Agency. The calendar of the WFD in the CWA is shown in Table 1.2. Date Descripcion December 2000 Publication and entry into force of the Water Framework Directive December 2003 Implementatio n of the Directiv e in the Spanish legal system. Implementatio n of the WFD: (Articl e 24 ), Delin eation of hydrographic areas and designation of t he competent authoriti es (Article 3). December 2004 Analysis of the characterisation of hydro gra phic boundary, study of the repercussions of human activities on the status of surface waters and groundwaters (anal ysis of pressures and impacts and the risk of non-compliance wi th the Directive objectives) and economic analysis of the costs of water-related se rvices and the current percen tage of costs recov e red (Articles 5, 6 and 7) ( IM PRESS documen t ). December 2006 Drawing up of the programme fo r monitori ng and control of the en vironmental and chemical status of surface water and th e ch emical and qua litative status of groundwater (Article 6). December 2006 Publication and public provision of th e ca lendar, th e consultation measure s and the working programme fo r drawing up the Cat ala n River Basin District Management Plan (Article 14). December 2007 Publication and public availability of a provis ional outline of the important subjects dealt with in determining measures and drawing up the Catalan River Basin Distri ct Management Plan (Article 14 ). December 2008 Publication and public availability of an out line of the draft of th e Catalan River Basi n District Mana gement Plan (Article 14). December 2009 Approval of the pro gramme of measures to be con tained in the work carried out (plans and programmes ) and the management measu res to be car ried out in order to at tain the objectives of th e Directive, namely the good ecological status of water by the end of 2015 (Article 11). I t should b e remembered, as set down in the Water Framework Dire ctive, that for the most appropriate me asures to be defined a cost-effe ctiveness analysis must first be carried out. December Drawing up of the Catalan River Basin Di strict Management Plan (new Hydrological Basin Chapter 1 Motivation and Justification. Exergy cost a ssessment of water r esources: Physical Hydrono mics 17 2009 Plan) (Article 13). December 2010 Member Stat es must ensure that th ey appl y a water-pricing policy that provides the necessary incen tives for efficient water us e an d an appropri a te tax contrib ution or policy that will lead to the full recovery of costs fo r water-related services. Costs will be broken down into domestic, industri al and agricultur al, an d financial, environmental and resource or opportunity costs will be take n into account (Arti cle 9). December 2012 The Member St ates must ensure th ey apply a combined approach involving the con t rol and reduction of p oint and diffuse sources of p ollution in line with best available techniques (Article 10). The programme of measures required to attain the good status of water will also be operational (Article 11 ). December 2015 The Member States must attain the good st atus of th eir bodies of water: the highest ecological and chemical status for surface water (inland and coastal) and the highest chemical and quantitative status of groun dwate r, with the exception of bodies of water that have been d eclared heavily modified an d t hose for which temporary exemption has been requested for a justified reason (Arti cle 4). Table 1.2. Schedule of the WF D in Catalonia (source: CWA). Planning is a tool that must enable real cond itions, in this case the aquatic environment, to be defined and objectives to be set, which must be met throug h the carrying out of a plan. These objectives are set for different l ong-term objectives (from 10 to 20 years in our case), and the plan is based on detailed studies of the current situation. The current regulation is contained in the Ed ict of 16th March 1999, published in the Official Gazette of the Catalan Government (DOGC) of 25th May 1999, which makes public the text that includes the determinations of the regulatory text of the Hydr ological Plan for the Internal Basins of Catalonia. The current Hydrological Plan for the Internal Basins of Catalonia , approved by Royal Decree 1664/1998 ( RD 1664/1998, de 24 de Julio, por el qu e se aprueban los Planes Hidrológicos de Cuenca ), which approved the river basin hydrol ogical plans (Official State Gazette - BOE- number 191, of 11th August 1998), is supported by technical bases. Describes the hydrological state in 1992 and foresees situat ions in 2002 and 2012 as a first and second horizon. The Hydrological Plan includes the Water Treatment Plan which, following the same philosophy, describes the quality of rivers at source (19 90) and sets objectives for the end of the Plan. Taking into account the WFD, it is consider ed the validity of the current Hydrological Plan and determines its updating and review a ccording to Decree 3/2003, of 4th November, which approved the reworked text of the legislation on water in Catalonia, called The Catalan River Basin District Management Plan. 1.6. The need of this PhD thesis WFD constitutes in this work a thinking framework from which a tool for water Governance is proposed. The Directive’s text provides general guidelines, but its implementation is still quite open to water managers interpretation. The final objective of the Directive is to provide each river basin with a water plan including all water resource management elements necessary fo r achieving the indicated Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 24 2.1. W ater as a natural r esource The two first sections of this chapter, 2.1 and 2.2, aim to a quantitative an d qualitative description of the main water bodies comprising the Hydrosphere from a global perspective. Such description will find its co mpletely meaning in the exergy assessment of the global fresh water resources carried out in Chapter 4. Water is one of the most widely distributed substances on p lanet Earth; in different forms and amounts it is available everywhere, interacting with the atmosphere, biosphere and lithosphere. The world’s water exists naturally in different forms and locations: in the air, on the surface, below the ground and in the oceans. Figure 2.1 shows that among the total water, only 2.5% is fresh water. This freshwater is divided into glaciers (68.7%), groundwater (30.1%), permafrost (0.8%) and the smallest amount, 0.4% is the surface and atmospheric water. The last group is constituted by freshwater lakes (67.4%), wetlands (8.5%), soil moisture (12.2%), atmosphere ( 9.5%), rivers (1.6%) and biological water (0.8%). Figure 2.1. Global distribution of the wo rld´s water. (Source: UN-WWAP, 2006) It is clear that water and water resources occupy a special place among natural human life and in powering many of the natural processes shaping the Earth. It is the basis for the entire organic world, an integral part of the ecological system and often the most important element of the landscape for hu man beings. However, it should also be mentioned that many of the world’s natural disasters and extremes are associated with water or the lack of it. Of greatest significance is fresh water as this is the most important natural resource. Life is not possible without it, because it has no substitute. Mankind has always consumed fresh water and have used it for many othe r purposes; however, for most of historical time the human impact on water resources was i nsignificant or local in character. The properties of natural waters including their changing and cleaning during their Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 25 movement through the hydrological cycle and their ability for self-purification allowed the fresh waters to retain their characteri stic purity, quantity and quality over time. 2.2. Hy dr osphere description and the hy drolo gical cycle. The Earth’s Hydrosphere is one of the oldest mantles of this planet and it appeared between 3.5 and 4 billion years ago (Klige et al., 1998). It developed together with and in close relationship to the lithosphere, the atmosphere, and then with life itself. Up to the present the mechanisms of the origin of wa ter on the Earth have not been completely explained (Kotwicki, 1991). However, the de gasification theory seems to be the most likely explanation (Rubey, 1951; Vinogradov, 1959; Artyushkow, 1970; Condie, 1989) . According to this theory the basic mass of the Hydrosphere formed as a result of the processes of melting and degassing the Ea rth’s mantle and it was determined by geophysical processes operating at depth. The Hydrosphere surrounding the Earth incl udes liquid, solid and gaseous forms of water, as indicated in the Figure 2.2º. The hydrological cycle transports this water about the Earth exchanging energy and moving materials as part of the p rocess. The hydrosphere unity is determined by not only its continuity but also the constant water exchange between all its elements. It includ es all mentioned types of natural waters – oceans, seas, rivers, lakes and glaci ers, un derground, atmospheric and biologically combined waters. All of them are interrela ted and water moves from one situation to another as the hydrological cycle progresses. The lower limit of the hydrosphere is assumed to be at the level of Mokhorovic surface, and the upper limit practically coincides with the upper atmospheric limit (B lyutgen, 1972). Although a large volume of freshwater exists ‘in storage’, it is more relevant to evaluate the renewable annual water flows , taking into account where and how th ey move through the hydrological cycle. Figure 2.2. Schematic of th e hydrologic cycle componen ts in present-day setting. (Source: UN, 2006) The schematic of the hydrological cycle in Figure 2.2 illustrate s how elements can b e grouped as part of a conceptual model th at has emerged from the new discipline of ecohydrology, which stresses the important relationships and pathways shared among hydrological and ecological systems (Zalewski et al., 1997). This conceptual model takes Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 26 into consideration the detail of the fluxes of all waters and their pathways while differentiating between two components: ‘blue water’ and ‘green water’. Blue waters are directly associated with aquatic ecosys tems and flow in surface water bodies and aquifers. Green water is what supplies terrest rial ecosystems an d rain-fed crops from the soil moisture zone, and it is green water that evaporates from plants and water surfaces into the atmosphere as water vapour. This concept was d eveloped by Falkenmark and Rockström (2004) who contend that the intr oduction of the concepts of “green water” and “blue water”, to the extend that th ey simplify the discussion for non-technical policy-makers and planners, may help to focus attention and resources on the often neglected areas of rain-fed agriculture, graz ing grassland, forest and wetland areas of terrestrial ecosystems and landscape management. The total volume of the contemporary Hydrosphere, according to current data (Shiklomanow and Rodda, 2004) is 1,396 million km 3 . As is was stated at the beginning of this chapter, fresh water in all its sta tes makes up only 2.5% of the total (see Table 2.1). Type of water Area of distribution (km 2 x 10 3 ) Volume (km 3 x 10 3 ) W ater layer (m) Fraction o total volume of hydrosphere (%) Fraction of fresh water (%) Averagere replacement time (yr) World Ocean 361,300 1,338,000 3700 95.81% __ 2,889 b Ground water (gravity and capi llary) 134,800 23,400 a 174 1.68% 1,400 d Predominantly fresh ground water 134,800 10,530 78 0.75% 29.23% 994 e Soil moisture 82,000 16.5 0.2 0.00% 0.05% 1 c Glaciers an d permanent snow cover: 16,228 24,064 1,463 1.72% 66.79% 12,850 c Antarctica 13,980 21,600 1,546 1.55% 59.95% 12,850 Greenl and 1,802 2,340 1,298 0.17% 6.49% 12,850 Arctic Islands 226 83.5 369.0 0.01% 0.23% 12,850 Mountainou s regions 224 40.6 181.0 0.00% 0.11% 1,600 d Ground ice of permafro st zone 21,000 300 14.0 0.02% 0.83% 10,000 d Water in lakes: 2,059 176.4 85.7 0.01% 10 c Fresh 1,236 91 73.6 0.01% 0.25% 10 Salt 822 85.4 103.8 0.01% 10 Swamp water 2,683 11.5 4.3 0.00% 0.03% 3 c River stream w ater 148,800 2.1 0.0 0.00% 0.01% 0 c Biological water 510,000 1.1 0.0 0.00% 0.00% 0 c Water in air 510,000 12.9 0.0 0.00% 0.04% 0 c Total volume of the hydro sphere 510,000 1,396,514 2,718 100% 3,023 Fresh water 148,800 36,029.20 235 2.58% 100% 8,995 (a) With no account of underground water of the Antarctic, appro ximately estimated at 2 million km 3 , including predominantly fresh water of abou t 1 million km 3 (b) Average value from Suomi, 1992 and Shiklomanov and Rodda, 200 4 (c) Average value from Buenfill , 2001 and Shikl omanov and Rodda, 2004 (d) Shiklomanov and Rodda, 2004 (e) Buenfill, 20 01 Table 2.1. Hydrosph ere content. (Source: Adapted from Shiklomanov and Rodda 2004, Buenfill 2001 and Suomi 1992) The waters of the Hydrosphere are in constant, usually cyclic, motion under the effects of solar radiation, the energy released from the Earth’s interior and gravitational forces. Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 27 In addition to free (gravitational) water, th e Lithosphere contains a large amount of physically and chemically combined water. Th e average content of that water amounts to 3.5% of the rock weight, i.e. some 0.24•10 24 g (Derpgolts, 1971). Combined water does not participate actively in the hy drological cycle, at least at recognizable time-scales, and is not taken into account in this kind of studies. Due to geological processes about 1 km 3 of water a year is released from the mantle through degasification and this rises gradually to the Earth’s surface. As a result of convection in the mantle, part of this matter can emerge through breaks in ocean rift zones related to oceanic ridges (Monin, 19 77). The global process of water exchange provides some stability in the distribution of waters between the land, the oceans and the atmosphere. This equilibrium is relative and can change in time, and these changes can lead to corresponding changes in hy drological and climatic conditions. Water evaporating from the surface of rese rvoirs, soil and vegetation enters into the atmosphere as water vapour where it is di ssipated upwards by turbulent diffusion and is transported by air currents from one place to another. With a temperature decreas e, water vapour is condensed, transforming it to a liquid or solid. During rainfall from clouds, part of the water returns to the Earth’s surface (inland cycle), and part of it returns to reservoirs in the form of runoff. Some precipitation can fall into the ocean, as was indicated in Figure 2.2. In fact, about 90% of water evaporated from the surface of the oceans and seas falls back into the sea, short-circuiting the cycle. A smaller part of it, about 10%, participates in the major cycle, being transported by atmospheric circulation to the land where, as rainfall, it can be involved in a number of smaller versions of the complete hydrological cycle when surface and ground water a nd ice drainage reaches the World Ocean, closing the complete cycle. Part of the water is combined a nd decomposed by plants. Solar heat evaporates water into the air from the Earth's surface. La nd, lakes, rivers and oceans send up a steady stream of water vapour; this spreads over the surface of the planet before falling down again as precipitation. Precipitation falling on land is the main source of the formation of the waters found on land: rivers, lakes, groundwater, glaciers. A portion of atmospheric precipitati on evaporates; some of it penetrates and charges groundwater, while the rest - as rive r flow - returns to the oceans where it evaporates: this process repeats again and ag ain. A considerable portion of river flow does not reach the ocean, having evaporated in the endorheic regions, those areas with no natural surface runoff channels. On th e other hand, some groundwater bypasses river systems altogether and goes directly to the ocean or evaporates. Quantitative indices of these different components of the global hydrological cycle are shown in th e diagram (Figure 2.3). Every year the turnov er of water on Earth involves 577,000 km 3 of water. This is water that evaporates from the oceanic surface (502,800 km 3 ) and from land (74,200 km 3 ). The same amount of water falls as atmospheric precipitation, 458,000 km 3 on the ocean and 119,000 km 3 on land. The difference between precipitation and evaporation from the land surface (119,000 - 74,200 = 44,800 km 3 /year) represents the total runoff of the Earth's rivers (42,700 km 3 /year) and direct groundwater runoff to the ocean (2,100 km 3 /year). These are the principal sour ces of fresh water to support life necessities and man's economic activities wa ter is in permanent motion, constantly changing from liquid to solid or gaseous phase, and back again. Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 28 Figure 2.3. Global precipitation, evaporation, evapotranspiration and run-off (So urce: UNEP, 2008) In addition to that, other part of the wate r contained by the Earth is in chemical compounds, such as crystal hydrate, sorba te and many other forms which are found in porous depostis in the Earth’s crust. This ch emically combined water can be removed from the total water exchange for thousands of years. The crustal rocks lose water during the process of metamorphization and subduction under the effects of high pressure and high temperature. This water rises through rock pores and appears on the Earth’s surface (Vinogradov, 1973). The water cycle on Earth is usually treated as a closed system. However, there exists some water external exchanges that, although small in quantity, do happen. Solar energy and energy from space, together with cosm ic dust, meteorites and meteors, arrive from space. The Earth in its turn gives back pa rt of its energy to space and dissipates hydrogen and helium to it (Alpatjyev, 1983; Kulp, 1951). This exchange of matter and energy brings about 0.01 km3 of water pe r year (Derpgolts, 197 1; Alpatjyev, 1969) from space to the Earth. At the sam e time part of the hydrosphere is lost due to the dissipation of light gases, and their escape b eyond the limits of the Earth’s gravitational field, amounting to about 0.1 km 3 per year (from 0.03 to 0.27 km 3 ) according to Yuri, 1959; Pavlov, 1977 and Alpatjyev, 1983. The hydrologic cycle is usually depicted on a global scale. Ho wever, the hydrologic cycle operates at many scales, from the hydrologic cycle of the Earth to the hydrologic cycle of a person's back yard. Generally, to use the small amount of the Earth's water that is suitable for humans (that is, only about one-third of one percent), people who manage water resources are most interested in the hydrologic cycle of watersheds. 2.2.1. The world ocean. The World Ocean holds by far the l argest part of total volume of water on the planet. However, in recent years, studies have appeared (Wallace, 1996) that show volumes which differ from the data here by between 0.7% and 10%. Including the water stored in the bottom silts of the oceans causes the 10% difference. Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 29 World Ocean has accumulated 3.06•10 25 J of heat (Stepanov, 1983). Every year it takes up almost twice as much solar en ergy as the land, and this factor determines its important role in the planetary heat exch ange. The major portion of this energy is employed in evaporation over 500.000 km 3 per year of water, which ensures global water exchange. Seawater composition will be an important parameter for the studies developed in this work. The average sewater composition is given in Table 2.2. Substance Concentration, (mg/g) Cl - 19.351 Na + 10.784 Mg 2+ 1.284 SO 2- 4 2.713 Ca 2+ 0.412 K + 0.399 HCO - 3 0.107 Br - 0.067 Sr 2+ 0.008 CO 2- 3 0.048 B(OH) - 4 0.003 F - 0.013 B(OH) 3 0.009 Sum 35.198 Table 2.2. The composition of average seawater. (Source: adap ted from Millero, 1996) 2.2.2. Glaciers and ice sheets About three-quarters of the world’s entire natural freshwater is contained within ice sheets and glaciers. Glaciers are giant “water reservoirs” and “c oolers” greatly influencing the climate and water regime of the Earth. Their state and th e changes from this state over time are important indicators of global climatic an d hydrological changes -past, present and future-. Cooling and warming and the advance and recession of glaciers result in the change of all the elements of the hydr ological cycle: precipitation, runoff and evaporation, and the volume of water stored on land and in the ocean. During glaciation a large amount of water becomes locked up as snow and ice on the land. As a result the volume of runoff decreases, the world ocean level falls by tens of metres, uncovering extensive areas of cont inental shelves. With the decline of glaciation, river flow increases, the volume of water in the ocean becomes larger, the level rises and the land area diminishes. The main source of water in most glacier systems is snow and ice melt. Some water is also derived from geothermal melting and inter nal deformation (Paterson, 1994). The total area of the present glaciation exceeds 16 million km 2 (what represents 3.23% of the Earth’s surface - 510,065,284 km 2 -). The mean ice thickness on this area is 1,700 m, and the maximum is more than 4,000 m (in Antarctica). The distribution of ice Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 30 sheets and glaciers and the water stor ed in them is given in Table 2.3. According to Korzun (1974), to estimate the mean thickness of ice, data fro m the few measurements from ice drilling and seismic sounding are use d. These data are applied by analogy to other glaciers taking into account their morphological features. Two great ice masses, the Antarctic and Gr eenland ice sheets contain about 99%: most of the iced water is concentrated in Anta rctica (almost 90%), while the r emainder is found in Artic (about10%) and in mountain glaciers. The total water volume in the ice across the globe is estimated to exceed 24 million km 3 . The accuracy of the assessment of that water storage in the Antarctica , for example, is about ± 3.0 million km 3 (Korzun, 1974). Antarctica and Greenland are the o nly places where continental ice sheets currently exist. These regions contain vast quantities of fresh water. The volume of ice is so large that if the Greenland ice sheet melted , it would cause sea levels to rise some six meters all around the world. If the Antarctic ice sh eet melted, sea levels would rise up to 65 meters (Shiklomanov and Rodda, 2004). 2.2.2.1. Antarctic ice sheet Antarctica is Earth's southernmost continent, overlying the South Pole. It is situated in the southern hemisphere, almost entirely south of the Antarctic Circle, and is surrounded by the Southern Ocean. At 14.4 m illion km², it is the fifth-largest continent in area after Asia, Africa, North America, and South America. About 98% of Antarctica is covered by ice, which averages at least 1.6 kilometres in thickness. Antarctica is the coldest place on Earth. At the 3-kilometer-high Vostok Station in Antarctica, scientists recorded Earth's lowest temperature: − 89 °C (British Antarctic Survey, 2006). For comparison, this is 11 °C colder than subliming dry ice. Antarctica is a frozen desert with little precipitation; the South Pole itself receives less than 10 centimeters per year, on av erage. Temperatures reac h a minimum of between − 80 °C and − 90 °C (in the interior in winter and re ach a maximum of between 5 °C and 15 °C (near the coast in summer). At the South Pole, the snow surface is 2,800 metres in altitude and the mean annual temperature is about –50ºC, but at the Sovi et Vostok Station, 3,500 metres above sea level, the mean annual tempera ture is –5 8ºC. Along the coast of East or West Antarctica, where the climate is milder, mean annual temperatures range from –20ºC to –9ºC (Hemingway, 1974). Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 31 Region Area of glaciers (km 2 ) Water volume (km 3 ) Water volume ( % ) Artic Greenland 1,802,400 2,340,000 9.69% Franz Josef Land 13,735 2,530 Novaya Zemlya 24,420 9,200 Severnaya Zemlya 17,470 4,620 Arctic Island s 226,090 83,500 Canadian Archipelago 148,825 48,400 Spitzbergen (Western) 21,240 18,690 Small Islands 400 60 2,254,580 2,507,00 0 10.38% Europe Iceland 11,785 3,000 Scandinavia 5,000 645 Alpes 3,200 350 Caucasus 1,430 95 21,415 4,090 0.02% Asia Pamir-Altai 11,255 1,725 Tien Shan 7,115 735 Dzungarian Ala Tau, Sayan Mountains 1,635 140 Eastern Siberia 400 30 Kamchatka, Pla teau of Koryak 1,510 80 Hindu Kush 6,200 930 Karakoram Pass 15,670 2,180 Himalayas 33,150 4,990 Tibet 32,150 4,820 109,085 15,630 0.06% Noth America Alaska (Pacific Coast) 52,000 12,200 Inner Alaska 15,000 1,800 USA 510 60 Mexico 12 2 67,522 14,062 0.06% South America Venezuela, Colo mbia, Andes, Tierra del Fuego 7,100 2,700 Patagonian Andes 17,900 4,050 25,000 6,750 0.03% Oceania New Zeland 1,000 100 New Guinea 15 7 1,015 107 0.00% Africa Kenya, Mount Kilimanjaro, Ruwenzori 23 3 0.00% Antarctica Antarctica 13,980,000 21,600,000 89.45% TOTAL 16,458,617 24,147,639 Table 2.3. Pres ent-day glaciation of continents and islands of the Earth. (Source: Shiklomanov and Rodda, 2004) Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 32 2.2.2.2. Artic ice sheet Greenland is the world's largest island, and is the largest depen dent territory by area in the world. It also contains the world's largest nation al park. Greenland ice sheet covers 81% of the tota l ar ea of Greenland. The coastline of Greenland is 39,330 km long, about the same length as the Earth's circumference at the Equator. The highest point on Greenland is Gun nbjørn at 3,694 metres. However, the majority of Greenland is unde r 1,524 metres elevation. Regarding the climatic change effects on this area, the annual mean temperature increased from -14.7ºC (1991) to -10.8ºC (2003), mean spring temperatures increased from -17.2º C to -13.6ºC, and fall temperatu res show a similar trend from -13.8ºC to - 10.3ºC for the 1991 to 2004 record. The larg est increase of 6º C was observed for mean winter temperatures, ranging from -25.3ºC (1991) to -19.3ºC (2003) (Steffen, 2005). The Greenland ice sheet is huge compared with all the other glaciers in the world, except that of Antarctica. Greenland (2 ,190,000 km 2 ) is mostly covered by ice (1,802,400 km 2 ), but isolated glaciers and small ice caps totalling 76,000 km 2 occur around the periphery. The mean altitude of the ice surface is 2,135 metres, and the bedrock surface is near sea level over most of the interior of Greenland, but the mountains occur around the periphery. Thus the ice sheet, in contrast to the Antarctic ice sheet is confined along most of its margin. The unconfined ice shee t does not reach the sea along a broad front anywhere, so that no large ice shelves occur. The climate of Greenland, though cold, is not as extreme as that of Antarctica. The lowest mean annual temperatures, about –31ºC, occur on the north central part of the north dome, and temperatures at the cres t of the south dome are about –20ºC (Enc.Brit., 1974). In Table 2.4, the average composition of glacie rs on Earth is shown. It was calculated by Brown (2002; cited by Valero D, 2008) after compiling the chemical composition of glacial runoff for the different regions of the world that appear in the Table 2.4. Ca 2+ Mg 2+ Na + K + HCO 3 - SO 4 2- Cl - Average comp. 12.69 2.59 18.44 1.98 48.15 27.38 7.71 Table 2.4. Concen tration of major ions in glaci al runoff fr om different regions of the w orld (in mg/l). (Source: adapted from Valero D., 2008) 2.2.3. Underground ice Permafrost is soil at or below the freezing point of water for two or more years. Ice is not always present, as may be in the case of nonporous bedrock, but it frequently occurs and it may be in amounts exceeding the poten tial hydraulic saturation of the ground material. Areas of permafrost extend over northeast Europe and the north and north-eastern parts of Asia, including the Arctic islands; they cover northern Canada and the fringes of Greenland and Antarctica, as well as higher parts of South America. The total area of permafrost is about 21 million km 2 , some 14% of the land area. In the Southern Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 33 Hemisphere (Antarctica, south America) permafrost covers about 1 million km 2 . The depth of permafrost ranges from 400 to 650 m. Underground ice within this range is found as vein formations and strata. The water stored as underground ice can be estimated only approximately due to lack of data and few studies (Grave, 1968) but the most likely figure is 300 thousand km 3 (Shiklomanov and Rodda, 2004). In the permafrost areas 150-200 km 3 of water occurs in the form of river ice. The annual snowfall over the Earth is about 1.7• 10 13 tonnes, and this snow covers an area of between 100 and 126 million km 2 (around 22% of the Earth’s surface). The distribution of snow varies considerably from year to year depending on climatic conditions. 2.2.4. Underground water The volume of gravitational water contained in the pores, fissures and fractures of the water-saturated strata of the Earth’s crust represents the natural storage of water underground. The geographical distribution of ground water is closely related to the geological structure of the Earth’s crust. It also depends considerably on the climatic factors: precipitation, condensation and evaporat ion, and particularly on the infiltration. Since runoff also depends on these factors, there is a stro ng relationship between ground water and runoff: ground water draining to rivers is included in the volume of runoff, being its most stable contribution to the hydrograph, especially during dry periods and drought. The reliable estimation of ground water storage is very difficult. The water content of water-bearing strata can be obtained approximately by multiplying the volume of water- bearing table by a water loss factor and effective porosity. The natural storage of ground water is determined down to the absolute depth of 2,000 m -the depth of the isobath which indicates approximately the distribu tion of the Earth’s continental crust-. Substance Granite Serpentinite Shale Cations or oxide SiO 2 39 31 5 Al 9 0.2 0 Fe 1.6 0.06 3.5 Ca 27 9.5 227 Mg 6.2 51 29 Na 9.5 4 12 K 1.4 2.2 2.7 Anions HCO 3 93 276 288 CO 3 00 0 SO 4 32 2.6 439 Cl 5.2 12 24 Fe 0 0 0 NO 3 7.5 6.8 0.9 PO 4 00 0 Table 2.5. Constituents of groun d wa ters from differ ent rock types. Concen trations in μ g/g. (source: White et al., 1963) Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 40 It is important to highlight that Rainfall Vari ation Coefficient in Spain is higher than in the other studied countries. The main reason is the Spani sh warm Mediterranean weather. Figure 2.6 represents the CVR of the Spanish Geography. Figure 2.6. Rainfall variation coeffici ent in Spain (Source: Couchoud, 2003) The high rainfall variability, together with high evapotranspiration rates and geographic separation of water resources and irrigation development, are important factors to account for in Spain. They all make the storage and delivery of water an enormous challenge. Aquifers can be used with surface water reservoirs to secure water supplies. There could be complemented with subsurface storage wh ich expands sto rage capacity, recharging aquifers during water excess periods with th e aim of having a resource when necessary. Using aquifers as storages is becoming a good alternative considering the existing constraints of building new dams due to en vironmental concerns and general lack of suitable sites. Its infrastructure costs are generall y cheaper, and water can be filtered, improving its quality. However, although the c oncept is not difficult, for u sing aquifers it is necessary to understand very well the hy drological and biological processes involved (NLWRA, 2001). In addition to natural causes, many factors can simultaneousl y affect runoff within large river basins,, such as abstractions for irriga tion and other agricultural purposes, as well as for industrial and municipal water supply. There can be soil drainage, deforestation, agrosilviculture, urbanization, opencast mini ng, and mine water pumping, stream bank straightening, and excavation of sand and gravel from river channels and other activities. There may be large scale diversions of flow from one basin to another and river flow control by reservoir operation. Analysis of the different anthropogenic factors influencing the hydrological regime leads to conclusions about the need to consider the role of all factors related to water abstractions from water bodies, including the c ontrol of runoff. It is necessary to do so in order to estimate the human impact on wa ter resources at the global scale. The factors causing a decrease in surface runoff and runoff from ground water are widely distributed. They are capable of exerting an especially pronounced effect on the state of water resources over large regions. In this connection the present section treats the changes in global use of fresh water for public water supply, industrial production and for agriculture, as well as water losse s due to evaporation from reservoirs. Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 41 2.3.3. General water use. Since antiquity, irrigation, drainage, and impoundment have been the three types of water control having a major impact on landsc apes and water flows. Since the dawn of irrigated agriculture at least 5000 years ago, controlling water to grow crops has been the primary motivation for human alteration of freshwater supplies. Today, principal demands for fresh water are for irrigati on, household and municipal water use, and industrial uses. Most supplies come from surface runoff, although mining of "fossil water from underground aquifers is an impor tant source in some areas. Th e pattern of water withdrawal over the past 300 years shows th e dramatic increases in this century. While the world's population tripled in the 20 th century, the use of renewable wa ter resources has grown six-fold. Within the next fifty years, the world population will increase by another 40 to 50 % (Figure 2. 7). This population growth -coupled with industrialization and urbanization- will result in an increasing demand for water and will have serious consequences on the environment. Figure 2.7. Histori cal tendency of population and hydr ol ogical resources wi thdrawals (Source: UN. 2008) The natural capacity of water of movement through the hydr ological cycle and its ability for self-purification gave birth to the illusi on that water resources would always be pure and readily available: it was almost as if th ey were a gift from the natural environment. In these circumstances, historically, the tradit ion arose of a careless attitude towards the use of water and water resources; the cost of waste water tr eatment was kept to a minimum and little was spent on protection of water resources from pollution. This situation has changed dramatically duri ng recent decades. In many regions and in most countries, the results of long-term neglect and misuse o f water resources have become obvious due to the increasing use of water resources a nd the transformation of land use in most river basins. For the first 50 years of the twentieth century the qu antity of water used globally grew to 785 km 3 (157 km 3 for every 10 years), while from 1951 to 1960 the growth rate increased more than fo urfold and it rose by 620 km 3 /year (Shiklomanov, I.A. and Rodda, J.C., 2004). This acceleration occurred principally because of the rapid expansion of irrigation, the growth of the volume of water used by industry and for the production of thermal power. Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 42 During recent decades the dramatic increase in water use due to the growth of the global economy has led to serious anthropogenic changes in the characteristics of the hydrology of rivers and lakes, particularly changes in the quantity and quality of their water. These changes, which have also affected ground water, have led to alterations in the water budgets of many river basins and changes in the available water res ources. At the present time, about 57% of total water withdrawal and 70% of global water consumption occurs in Asia where the major irrigated lands o f the world are located. During the next few decades, accor ding to UNESCO predictions, the most intensive growth in water withdrawal is expected to occur in Africa and South America -by 1.5- 1.6 times- and the smallest in Europe and North America -1.2 times- (Figure 2.8). Figure 2.8. Water withdrawal and consumption b y continents (Source: Unesco , 2008) In addition to water consumption, water use by the humans also affects to its quality. Almost any human use means water quality degr adation. Specific pollution due to use is detailed in section 2.5, use by use. Waste water treatment is a duty in order to avoid infectious illnesses derived from that water pollution, specially keeping in mind that 1 l of waste water can pollute 8 l of potable water (Cech, 2003). The solution has to be based on effective sewage collection systems and water treatment plants. Before detailing the amount and degradation of water in each sector, the parameters defining water quality are going to b e analyzed in section 2.4. 2.3.3.1. Consumptive and Non-Cons umptive Water Use Consumptive water use refers to water that is not returned to stre ams after use. For the most part, this is water that enters the at mospheric pool of water via evaporation (from reservoirs in arid areas) and from plant transpiration (especi ally from thirsty crops such as corn and soja). Irrigated agriculture is responsible for most consumptive water use, and decreases surface run-off. An extreme ex am ple is the Colorado River, which has most of its water diverted to irrigated agricult ure, so that in a normal year, no water at all reaches the river’s mouth. Agriculture is responsible for 87 % of the to tal water used globally. In Asia it accounts for 86% of total annual water withdrawal, compared with 49% in North and Central America and 38% in Europe. Rice growing, in particular, is a heavy consumer of water: it takes some 5,000 litres of water to produ ce 1 kg of rice. Compared with other crops, rice production is less efficient in the way it uses water. Wheat, for example, consumes 4,000 m 3 /ha, while rice consumes 7,650 m 3 /ha. Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 43 A great deal of water use is non-consumptive, which means that the water is returned to surface runoff. Usually that water is contaminated however, whether used for agriculture, domestic consumption, or industry. The World Health Organization (WHO) estimates that more than 5 million pe ople die each year from diseases caused by unsafe drinking water, and lack of sanitation and water for hygiene. This has economic effects as well: an outbreak of cholera in Latin America killed hundreds of people, and cost hundreds of millions of dollars. 2.3.4. Water stress, virtual w ater and water footprint There are several indicators evaluating the basic human necessities per capita. The most known and used is the water stress index , established as 1,000 m 3 /person/year. Water stress results from an imbalance between water use and water resources. The water stress indicator measures the proportion of water withdrawal with respect to total renewable resources (WWC, 2009). It is a criticali ty ratio (CR), which implies tha t water stress depends on the variability of resources. Water stress causes deterioration of fresh water resources in terms of quantity (aquifer over-exploitation, dry rivers, etc.) and quali ty (eutrophication, organic matter pollution, saline intrusion, etc.) The value of this criticality ratio that indicates high water stress is based on expert judgment and experience (Alc amo et al., 2000). It ranges between 20% for basins with highly variable runoff an d 60% for temperate zone basins. In the map shown in Figure 2.9, an overall value of 40% is taken to indicate high water stress. It can be seen that the situation is heterogeneous ov er the world. This ratio can not be reached by many African countries, in Middle East or in Asia. Figure 2.9. Water stress in dicato r (Source: WWC, 1999) A 1997 UN assessment of freshwater resour ces found that one-third of the world's people experience moder ate to high water stress. Moderate water stress levels are said to occur when water consumption exceeds ren ewable freshwater supply by 1 0 per cent. The problems are most severe in Africa and West Asia. In Asia, where water has always Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 44 been regarded as an abundant resource, per ca pita availability declined by 40-60% between 1955 and 1990. Projections suggest that most Asian countries will have severe water problems by the year 2025. Most of Africa historically has been water-poor. The role of virtual water deserves atten tion as well. The term virtual water was introduced by Tony Allan in the early 1990s (Allan, 1993 ). It is defined as the volume of water required to produce a commodity or service (Allan, 1999; Hoekstra, 1998). When there is a transfer of products or services from one place to another, there is little direct physical transfer of water (apart from the water content of th e product, which is quite insignificant in terms of volume). There is however a significant transfer of virtual water. For producing 1 kg of grain, around 1.5 m3 of water are required. For producing 1 kg of cheese, about 5000 l of water are needed and for 1 kg of beef we need in average 16000 kg of water (Chapagain and Hoekstra, 2003). According to a recent study by Williams et al. (2002), the production of a 32-megabyte comp uter chip of 2 grams requires 32 kg of water. The virtual water trade balances for thirteen world regions can be identified in Figure 2.10, where the largest virtual water trade flows are also drawn. This information has been extracted from the Value of Water Research Report Series No.12 , by IHE Delft (Hoekstra, 2003). There are a set of publicati ons regarding these issues, containing high amount of information. Considering the peri od 19 95-1999, the top-5 list of countries with net virtual water export is: United Sta tes, Canada, Thailand, Argentina, and India. The top-5 list of countries in terms of net virtual water import for the same period is: Sri Lanka, Japan, Netherlands, Republic of Korea, and China. Countries that are relatively close to each other in terms of geography and devel opment level can have a rather different virtual water trade balan ce. While European countries such as the Netherlands, Belgium, Germany, Spain and Italy import virtual water in the form of crops, France exports a large amount of vi rtual water. In the Middle East we see that Syria has net export of virtual water related to crop trade, but Jordan and Israel have net import. In Southern Africa, Zimbabwe and Zambia had net export in the period 1995- 1999, but South Africa had net import (Hoekstra, 2003). In terms of global trade, virtual water does not only raise awareness about water interdependencies, but it can also serve also as a means for improving water efficiency. Figure 2.10. Virtual water trade balances of thirteen world regions over th e period 1995-1999. The arrows show the largest net virtua l water flows between regions (>100 Gm 3 ). (Source: Hoekstra, 2003) Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 45 In a further step, a broader indicator, the water footprint , links virtual water and world trade. Via the sum of domestic water use an d virtual water, it can be considered how water used for the production of export commodities on the global market can contribute significantly to the changes in local and regional water systems The water footprint of a country is defined as the volume of water needed for the production of goods and services consumed by the inhabitants of the country (Hoekstra and Chapagain, 2004). It can be calculated with either the top-down approach or bottom-up approach. In the top-down approach, the water footprint is calculated as the sum of water use in the country plus gross virtual water import into the country minus gross virtual water export. In the bottom-up approach, the individual water footprints of the inhabitants of a country are aggrega ted to get the total water foo tprint of a country. Individual water footprints are calculated by multiplying all consumed goods and services with their respective virtual water cont ent. Based on the top-down approach, the global average water f ootprint is found to be 1,240 m 3 /yr/cap. There are large differences between countries. In the USA, the average water footprint is 2,500 m 3 /ca p/yr, while it is 700 m 3 /cap/yr in China (Figure 2.11). Figure 2.11. Average national water footprint per capital (m 3 /capita/yr) in 2004. (source: Hoekstra and Ghapagain, 2007) It has been noted, for example, that since Japan consumes large quantities of America n cereals and soybeans, it might be suggested th at this in turn leads to the mining of aquifers and further water use of rivers in North America. Figure 2.11 shows national water footprints around the world. Green means that the nation’s water footprint is equal to or smaller than global average. Countries with red have a water footprint beyond the global average. According to the report Alive Planet 2008 of WWF-Adena (WWF-Adena, 2008), Spain occupies the fifth position on world-wide scal e as far as the deno minated hydric track, a variable that analyzes the volume of fresh water used generally to produce the goods and services consumed by each citizen. Spain, in addition, comprises of the group of States of the Mediterranean (Portugal, Ital y, Greece and Cyprus) that every time has a greater “brought about hydric stress” because the water begins to become a little good Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 46 to the most important being the demand than the amount available, situation that will get worse as a result of the climatic change. A thousand tons of water produces one ton of wheat, which has a market value of US $200. In contrast, the same amount of water used in indus try yields an estimated US$14,000 of output -70 times as much- (Hun t, 2004). Those countries that can afford to import grain, therefore, often find that imports of virtual water –the substitution of food imports for irrigated agriculture prod uction paid for by urban and commercial growth- are an attractive alternative to continued use of water in agriculture. According to Hoekstra (2003), more than 20 0 international water systems exist in the world, and about 50 to 60% of the global population resides within them. It is clear them the huge importance of the security in the water systems: improving food self- sufficiency by a basin country may lead to a conflict with oth er nations sharing in an international water system. Importing free virtual water , may be seen as a mechanism to abate conflicts among basin countries . Tradeoffs between trading real water and virtual water should be examined before carrying out a large-scale transbou ndary water transfer scheme. After examining general water issues on water, the macro vision of the situation has been drafted and it is time now to concrete some specific relevant aspects in this PhD thesis elaboration. In particular, the type of sources polluting the water bodies, and the parameters defining that water quality. The de scription, both in quantity and quality, o f the point and diffuse pollution sources within a watershed will be a key point in the watersheds evaluation. Therefore, it is necessa ry to review first the most important used parameters to characterize the water quality. 2.4. P arameters defining w ater quality As important as the am ount of the water resource, is the quality of it. The concept describing non desirable elements in water is pollution, and a water body is considered to be polluted if it is unusable for a particul ar purpose. It can occur either naturally or through human activity. In the past, the basic chemical and b ioche mical processes affecting water quality were the result of nature. Long before humans settled along the banks of rivers such as the Yangtze in China and the Nile in Egypt, sediment-laden floods carried metals an d minerals that contributed to poor quality of water. Ancient floods of the Mississippi River filled adjacent oxbow lakes and marshes with organic ma terials such as decaying plants and animals. The aridity of the Col orado River watershed caused salt from alkaline soils to enter the river for thousand s of years before human cultivation began. Groundwater in certain regions, or at great depths, contained dissolved minerals that rendered it unfit for human consumption. Th ese natural processes greatly affected water quality around the world long before the negative influences of humans. Unfortunately, humans have caused incredible levels of water pollution. The U.S. Environmental Protection Agency reported that 40 percent of the streams, lakes, and estuaries that were assessed (32% of all U.S. waters) were no t clean enough for uses such as fishing and swimming. Leading pollu tants in these impaired waters included Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 47 sediments, bacteria, nutrients, and metals. Runoff from urban areas and agricultural lands were the primary sources of these pollutants. The recent Directive 2008/105/EC of the Euro pean Parliament and of the council of 16 December 2008 defines some envi ronmenta l water quality standards in accordance with the provisions and objectives of Dir ective 2000/60/EC, which establishing a framework for Community action (a strategy against pollution of water, which requires further specific measures for pollution control and environmental quality standards) in the field of water policy. This Directive lays down Environmental Quality Standards (EQS) for priority substances and certain other pollutants as pr ovided for in Article 16 of Directive 2000/60/EC, with the aim of achieving good surface water chemical status and in accordance with the provisions and objecti ves of Article 4 of that Directive. Member States may designate mixing zones (article 4) adjacent to points of contaminants discharge (which permissible c oncentrations are listed in Part A of its Annex I), which will have to be included in river basin management plans produced in accordance with Directive 2000/60/EC. On the basis of reports from Member Sta tes, including reports in accordance with Article 12 of Directive 2000/60/EC and in particular those on transboundary pollution, the Commission shall review the need to amend existing acts and the need for additional specific Communitywide measures, such as emission controls. A Member State shall not be in breach of its obligations under this Directive as a result of the exceedance of an EQS if it can demonstrate that the exceedan ce was due to a source of pollution outside its national jurisdiction. Finally, the Commission shall consider inter alia the substances set out in its Annex III for possible identification as priority substances or priority hazardous substances. The Commission shall report the outcome of it s review, accompanied with relevant proposals, to the European Parliament and to the Council by 13 January 2011. 2.4.1. Pollution Sources In this section it is summed up where pollution comes from and how it is transported to waterbodies (such as rivers, lakes, or estuar ies). Pollution sources are divided into two categories: point source and nonpoint sources. A point source of pollution is generally defined as contamination discharged through a pipe or other discrete, identifiable location. Pollution from a point source is relatively easy to quantify, and impacts can be di rectly evaluated. Nonpoint source pollution is generated from broad, diffuse sources that can be very difficult to identify and quantify. Such a pollution enters rivers, lakes and other water bodies through surface and groundwater move ment, and even from the atmosphere through precipitation. Point source and nonpoint source pollution are caused by human activities. It is important to separate these activities from natural water quality degradation, sometimes Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 48 called “background pollution” or “natural contamination”. Naturally degraded water quality, as explained before, can be cause d by chemical reactions between water and metals and minerals, natural erosion, forest litter, natural mig ration of salts, and other normal processes of the hydrologic cycle. In Table 2.10, some examples of point and nonpoint sources are listed. Point source pollution: Nonpoint source pollution Factories and w astewater treat ment plants Lawns, gardens and golf courses Landfills Agricultural practices Abandoned m ines Street re fuse Underground and above-gro und stor age tanks Contruction activities Dredging activities Table 2.10. Point source and non-point source polluti on. (Source: adapted from Cech, 2003) 2.4.2. Basic parameters in water quality The monitoring of water quality of rivers dates back to around 1890 when some European rivers, such as the Thames and the Seine, highly contaminated due to domestic sewage, were monitored in terms of a few simple parameters of dissolved oxygen, pH, etc. With the rapid industrializat ion and development of the energy sectors and high-input agriculture, there has been an exponential rise in the num ber of water quality indicators, corresponding to the increasing diversity of pollutants (Meybeck and Helmer, 1989). These indicators, including the earliest monitored simple indicators, major irons, organic, and inorganic matters, and toxic pollutants, etc., co ver a broad range of water quality. In order to comprehensively evaluate the water quality, a variety of evaluation methods such as the single index, fuzzy mathematics, p rincipal factor analysis, specialist evaluation, gray correlation, radial basis function, artificial neural network, and comprehensive index evaluation, etc. have been established. Common to all those models is the unavoidable subjectivity, of the weighting factor for each involved indicator, mathematical mode ls or corresponding parameters. Due to the subjective weighted factors out of so-called specialist inquiry, contradictory evaluations may be resulted for the same water quality data with different specialist groups. For reasonable and consistent water resource exploi tation and management, it is essential to pursue a unified objective assessment of water quality. The main parameters found in water quality reports are: - Temperature, pH, turbidity, hardness and dissolved oxygen - Inorganic chemicals: metals and minerals - Organic chemicals: natural organic ch emicals, synthetic organic chemicals (including pesticides). - Nutrients: nitrogen and phosphorus. - Eutrophication and microorganisms Significant pollution sources in river basins, such as large industrial plants, may be termed ‘hot spots’ and prioritized for clean- up within a river basin management plan. It is important to consider not only the level or concentration of individual substances, but also their combined effect. It is very expensive to monitor water quality for the presence of numerous chemicals, each of which must be tested for separately. By Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 49 monitoring the populations of certain organisms, called indicator organisms (such as frogs, molluscs or certain insect species), it is possible to create a picture of how the water body is being affected over time. These eco toxicological methods provide a more cost-effective way of assessing the impact of industrial discharges on ecosystems. Measurements of chemical parameters are usually expressed in the physical unit of milligrams per litre (mg/l) or grams per cubic meter (g/m 3 ). The concentration of trace constituents is usually expressed as micrograms per litre ( μ g/l) or nanograms per litre (ng/l). The concentration can also be expressed as parts per million (ppm), which is a mass to mass ratio. The relationship between mg/l and ppm is given in Eq. 2.1: Eq. 2.1 . fluid of gravity specific l mg ppm _ _ _ / = For dilute systems, such as those encountered in natural waters and wastewater, in which one litre of sample weigh appr oximately one kilogram, the unit of mg/l or g/m 3 are interchangeable with ppm. The terms part per billion (ppb) and parts per trillion (ppt) are used interchangeably with μ g/l and ng/l, respectively. 2.4.2.1. Temperature Many physical, biological, and chemical characteristics of surface water are dependent on temperature. Excessive temperature change s can accelerate chemical processes and can be detrimental to aquatic plants and wild life. Increased heat in water can reduce its ability to hold dissolved oxygen, while sudde n temperature “shocks”, often caused by heated industrial water released into a lake or stream, can be deadly to many aquatic species. Removal of shade trees and shrubs along a shoreline can also affect th e temperature of a water body, particularly during warmer seasons of the year. Fish respond to water temperature variations and often move to new locations when temperature changes vary by little more that 1 to 4ºC. Water temperature is greatly affected b y depth. Surface water is generally much colder at greater depths than shallow water, since it requires more ti me to absorb heat. Such temperature variations can cause lakes to “t urn over” in the spring and fall, creating variable water quality characteristics. By contrast, groundwater at depths less than 91 meters generally maintains a constant tempera ture of approximately 10ºC, while surface water in lakes can rang e between a frozen state to 21-27ºC and higher during the summer. 2.4.2.2. pH The hydrogen potential, pH, is defined as th e negative logarithm of the hydrogen ions activity. For dilute solutions, however, it is convenient to substitute the activity of th e hydrogen ions with the molarity (mol/l) of th e hydrogen ions. As it is well known, the common pH scale extends from 0 (very acidic with a high concentration of positive hydrogen atoms, H + ) to 14 (very alkaline, or basi c, with a very high concentration of negative hydroxyl ions, OH - ). A pH of 7.0 represents exact neutrality of water at 8ºC. Raw water found in rivers and lakes genera lly has a pH between 4 and 9, while pure distilled water is at 7. Fish have a narrow range of pH preference that varies by species. Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 56 analyzer has been developed, in conjunction with the space program, which can be used to detect TOC concentrations in the ppb range. Such instruments are currently being used to detect the residu al TOC in the treated effluent from microf iltration and reverse osmosis treatment (Visco et al., 2005). Theoretical Oxygen Demand (ThO) comple ments these la boratory tests and it is determined from the chemical formula of the organic matter. 2.4.2.12. Total Oxygen Demand (TOD). This method involves the oxidation of the sa mple to stable end products in a platinum- catalyzed combustion chamber. TOD is determi ned by measuring the oxygen content of the inert carrier gas, nitrogen. TOD measur ements are becoming more popular because of their quickness in determining what is entering the waste water treatment plants and how the plant is responding. The results obtai ned generally will be equivalent to those obtained in the COD test. 2.4.2.13. Interrelationships betw een BOD, COD and TOC The TOC of a wastewater can be used as a measure of its pollution characteristics, and in some cases it has been possible to relate TOC to BOD and COD values. If a valid relationship can be established between resul ts obtained with the TOC test and the results of the BOD test for a given wastewa ter, use the TOC test for process control is recommended (Metcalf and Eddy, 2003). Typical values for the ratio of BOD/COD for untreated municipal wastewater are in the range from 0.3 to 0.8 (Table 2.12). If the BOD/COD ratio for untreated wastewater is 0.5 or greater, the waste is considered to be easily treatable by biological means. If the ratio is below about 0.3, either the waste may have some toxic components or acclimated microorganisms may be required in its stabilization. Type of wastewater BOD/COD BOD/TOC COD/TOC Untreated 0.3-0. 8 1.2-2.0 2.909 After primary settling 0.4-0.6 0.8-1.2 2 Final effluent 0.1-0.3 a 0.2-0.5 b 1.75 Table 2.12. Relation among organic measurem ent parameters (Source: adapte d from Metcalf an d Eddy, 2003) 2.4.2.14. Dissolved oxygen Oxygen comprises about 21% of the atmos phere but only a fraction of 1% of water. Where atmosphere and water meet, the great difference in proportions causes oxygen to become dissolved in water. Dissolved oxyg en (DO) is comprised of microscopic bubbles of oxygen gas, O 2 , in water and is critical for the support of aquatic plants and wildlife in lakes and streams. DO is prod uced by diffusion from the atmosphere, aeration of water as it passes over falls and rapids, and as a waste product of photosynthesis. It is affected by temperature, salinity, atmospheric pressure, and oxygen demand from aquatic plants and animals. It is measured in parts per million or milligrams per litre. Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 57 Most aquatic plants and animals need dissolved oxygen in water to survive. However, oxygen is only slightly soluble in water. Th e actual quantity of oxygen that can be present in solution is governed by the solubili ty of the gas, the partial pressure of the gas in the atmosphere, the temperature and the concentration of the impurities in the water (Metcalf and Eddy, 2003). Species, such as trout, req uire medium to high levels of DO, while warm-water fish such as catfish or carp require lower concentrati ons. High levels of dissolved oxygen allow a variety of aquatic organisms to thrive. Ideally, dissolved oxygen levels should be near saturation levels in surface water to provide maximum levels for fish. Elevated levels of dissolved oxygen also make drinking water taste better but can be corrosive to water pipes. 2.4.3. Nutrients Plants, animals, microorganisms, and even single-cell bacteria must extract substances from the environment for energy and growth. These substances are called nutrients and include nitrogen (N), phosphorus (P), magn esium (Mg), calcium (Ca), and iron (Fe). Nitrogen, phosphorus, and associated compou nds are particularly important in the study of water quality. 2.4.3.1. Nitrogen Nitrogen is important as plant nutrient fo r crop production, lawns, landscaping, golf courses, forest growth, and other vegetation. It is most abundant in its atmospheric form (N 2 ). Nitrogen gas comprises 78.1% of the Earth’s atmo sphere, by volume (Los Alamos, 2001) Nitrate (NO 3 - ) is created by bacterial action on ammonia (NH 3 ), by lightning, or through artificial processes that include extreme heat and pressure. Nitrate is found in soluble form in both surface and groundwater. It is not bound by soil particles, is consumed by plants, and converts into gaseous forms by microbial action. Nitrates can pollute groundwater aquifers by leaching through soils , or they can move laterally with surface water or subsurface flow to contaminate surface waters. In proper amounts, nitrates are very beneficial. However, excessive concentrat ion in water can cause health problems if consumed by humans (Cech, 2003). The Maximum Contaminant Level (MCL) esta blished by the U.S. Environmental Protection Agency for nitrate is 45 ppm, which equals 10 ppm nitrate-nitrogen (NO 3 - N). In Europe, the Council Directive 75/440/CEE, of 16 June 1975, concerning the quality required of surface fresh water specifies, in its attached 2, an imperative maximum value of 50 mg NO 3 - /l, and recommended values of 25 mg NO 3 - /l and 2 mg N Kjeldahl /l , respectively. N Kjeldahl include no NO 3 - contribution. Nitrite (NO 2 - ) is a salt formed by the action of bacteria on ammonia and organic nitrogen. Nitrite, also found in soluble form in water, is a n intermediate form created by bacterial action on ammonium (NH 4 + ) or nitrate (NO 3 - ). Ammonium is converted to the nitrite and nitrate forms rather quickly by nitrifying bacteria. These add oxygen to the ammonium ion and convert it to nitrate. Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 58 Ammonia toxicity is a problem for aq uatic life, whereas nitrite toxicity is a problem for infants. Nitrites react directly with huma n blood and other warm-blooded animals to produce methemoglobin. Methemoglobin destro ys the ability of red blood cells to carry oxygen and can cause a condition called meth emoglobinemia, or “blue baby” syndrome in infants primarily under three months of age. Water with nitrite levels exceeding 1.0 mg/l should not be used for feeding infants. The drinking water standard for nitrates is 10 mg/l. Nitrite toxicity in fish is greater in water with lo w DO levels because, as mentioned, nitrite reduces the ability of blood to carry oxygen. Nitrites can produce “brown blood disease” in fish and occur mostly in farm or commercial fish ponds when sediments are disturbed. Disturbance typically occurs duri ng the spring and fall turnovers or through mechanical agitation to increase dissolved oxygen levels. Although fish tolerance for nitrite is low (often less than 0,15 mg/l), their tolerance for nitrate (NO 3 - ) is high, typically grater than 1000 mg/l (CAST-US, 1996). Ammonia (NH 3 ) and ammonium (NH 4 + ) are commonly found in surface water, in the soil, and as a byproduct of decaying plant tissue and decomposition of animal waste. Ammonia and ammonium are rich in nitrogen and excellent f ertilizers. Ammonia levels at 0,1 mg/l usually indicate polluted surface waters, whereas readings above 0,2 mg/l can be toxic for many aquatic species. (Cech, 2003). High levels of ammonia are often found downstream of wastewater treatment plants and near ponds that have large populations of water fowl, such as duck s and geese, which produce waste. 2.4.3.2. The Nitrogen Cycle The nitrogen cycle (Figure 2.12) is driven by nitrogen, oxygen, and bacteria. It is the natural process of converting the reservoir of nitrogen gas from the atmosphere into usable forms of nutrients for plants and animals. The nitrogen cycle includes complex interactions with various forms of nitr ogen, notably: atmospheric nitrogen (N 2 ), organic nitrogen (N), nitrite (NO 2 - ), nitrate (NO 3 - ), ammonia (NH 3 ) and annonium (NH 4 + ). Each form of nitrogen affects plant utilization and can have negative impacts on water quality. The nitrogen cycle includes four main components: nitrogen fixation, mineralization, nitrification and denitrification (Figure 2.12). Figure 2.12. Nitrogen Cycle (source: Pidwirny, 2008) Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 59 Nitrogen Fixation Animals, including humans, cannot utilize nitrogen gas from the atmosphere or from inorganic compounds. Instead, nitrogen must first be converted into an organic form (nitrogen combined with carbon), through a process called nitrogen fixation. This process requires substantial amounts of ener gy to break apart the nitrogen molecule, since it has a triple bond between the two ni trogen atoms, making the molecule almost inert. Nitrogen gas (N 2 ) will react with oxygen only in the presence of high temperatures and pressures, or through bacterial activity, to create organic nitrogen (N), nitrate (NO 3 - ) or ammonia (NH 3 ). This process can be caused by atmospheric fixation by lightning, biological fixation by bacteria and algae, and industrial fixation caused by combustion reactions in power plants, chemical processe s to make fertilizers, or inside internal combustion engines. Industrial fixation requires great pressure and temperatures. Biological fixation accounts for about 70% of the total conversion of nitrogen into biologically useful forms of nitrate. The Rh izobium bacteria in root nodules of legume crops such as clover, alfalfa pinto beans, and soybeans, in surface water environments such as wetlands complexes, and in the soil can convert nitrogen gas in the atmosphere into biological matter. Approx imately 20% of all nitrogen fi xation –from nitrogen gas to ammonia- occurs through industrial proce sses. Atmospheric nitrogen fixation from discharge lightning accounts for less than 5% of total fixed nitrogen conversion from atmospheric nitrogen (N 2 ) to nitrate (NO 3 - ). Agriculture may now be responsible for approximately 35% of all nitrogen fixati on on Earth through the use of fertilizers produced by industrial fixation and biolog ical fixation caused by the production of legume crops (Bezdicek and Kennedy, 1998). The average nitrogen fixation rates are shown in Table 2.13. Fixed N Type of Fixation (10 6 metric tons/yr) Nonbiological Industrial about 50 Combustion about 20 Lightining about 10 Total nonbiological about 80 Biological Agricultural land about 90 Forest and nonforest lan d about 50 Sea about 35 Total biological about 175 Table 2.13. Nitrogen Fixati on rates. (Source: Cech, 2003) Mineralization Mineralization, or decay, is the process of organic matter, s uch as dead plants and animal waste, decomposing in the presence of oxygen. The principal storehouse for nutrients found in the soil is within organic matter, such as decaying plants or animal waste. Organic matter can hold more than 96% of all soil nitrogen (Donahue, R. et al, 1983). Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 60 Nitrification The process of organic nitrogen (N) changing into nitrate (NO 3 - ) is called nitrification and it is a rapid anaerobic process that requires bacterial action. The common soil bacterium Nitrosomonas oxidizes ammonia (NH 3 ), or organic matter, into nitrite (NO 2 - ). Nitrobacter, another common bacterium, relatively quickly oxidizes nitrite (NO 2 - ) into nitrate (NO 3 - ). 2.4.3.3. Phosphorus In contrast to nitrogen, phosphorus does not exist in a gaseous state but occurs naturally as a salt in the mineral apatite. Apatite, Ca 5 (PO 4 ) 3 (OH)0.33F0.33Cl0.33, is found in igneous, metamorphic, and sedimentary rocks. Phosphorus is a common nutrient found in soil and water, and is quickly bound to soil particles or is consumed by plants. Phosphorus can originate from dissolved leach rate from rocks, from decomposing organisms, animal waste, ma nufacturing processes, effluent from wastewater treatment plants, and as artifi cial fertilizers. Much of the phosphorus found in sewage effluent is from synthetic detergents. Phosphorus by itself does not have any not able health effects on humans. However, phosphorus levels above 1.0 mg/l may interfere with coagulation processes at water treatment plants. This ca n hinder the remo val of microorganisms bound to sediments and other particles from drinking water (WHO, 1996). Nonpoint source pollution of eroding sediments in runoff is the primary mechanism whereby phosphorus enters surface water. In many cases, point sources, such as wastewater treatment plants, are also very important contributors. Lake a nd reservoir sediments serve as phosphorous sinks and ca n cause excessive growth of algae and phytoplankton (Cech, 2003). Such growth often occurs when summer warming conditions of the normally cooler water at th e bottom of a lake stimulate the release of phosphorus from the sediments at the bottom of the water body. 2.4.3.4. The Phosphorus Cycle Processes of the hydrology cycle add phosphorus to the soil where it can be consumed by plants. Decaying plants and animal waste decompose and return phosphorus to organic form in the soil, where the phosphorus cycle continues. The usual forms of phosphorus that are found in aqueous solutions include the orthophosphate, polyphosphate, and organic phosphate. The orthophosphates, for example, PO 4 3- , HPO 4 2- , H 2 PO 4 - , H 3 PO 4 , are available for biological metabolism without further breakdown. The polyphosphates include those molecules with two or more phosphorus atoms, oxygen atoms, and, in some cases, hydrogen atoms combined in a complex molecule; they undergo a quite slow hy drolysis in aqueous solution and revert to the orthophosphate forms. The organically bound phosphorus is usually of minor importance in most domestic wastes, but it ca n be an important constituent of industrial wastes and wastewater sludges (MSU, 2008). When plant materials and was te products decay through bacterial action, the phosphate is released and returned to the environment for reuse. Much of the phosphate eventually is washed into the water from erosion and leaching. Again water plants and algae utilize the phospha te as a nutrient. Studies have shown that Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 61 phosphate is the limiting agent in the growth of plants and algae (Cech, 2003). If not enough is present, the plants are slow growing or stunted. If too much phosphate is present excess growth may occur, particularly in algae. A large percentage of the phosphate in water is precipitated from the water as iron phosphate which is insoluble. If the phosphate is in shallow sediments, it may be readily recycled back into the water for further reuse . In deeper sediments in water, it is available for use only as part of a general up lifting of rock formations for the cycle to repeat itself. Human influences on the phosphate cycle come mainly from the introduction and use of commercial synthetic fertilizers. Plants may not be able to utilize all of the phosphate fertilizer applied. As a consequence, much of it is lost form the land through the water run-off (Figure 2.13). The phosphate in the water is eventually preci pitated as sediments at the bottom of the body of water. In certain lakes and ponds th is may b e redissolved and recyled as a problem nutrient. Animal wastes or manure may also be applied to the land as fertilizer. If misapplied on frozen ground during the wi nter, much of it may be lost as run-off during the spring thaw. In certain area very large feed lots of animals, may result in excessive run-off of phosphate and nitrate into streams. Other human sources of phosphate are in the out flows from municipal sewage treatment plants. Without an expensive terti ary treatment, the phosphate in sewage is not removed during various treatment opera tions. Again an extra amount of phosphate enters the water. Figure 2.13. The phosphorus cycle (source: MSU, 2008) At this point, the required revision on th e parameters commonly used to characterize water quality is concluded. It has been devel oped along section 2.4 because, as indicated at its beginning, all those water quality features need to be clearly stated to go further in the analysis. The nitrogen and phosphor cycl es have been quite in detail explained because of its high importance within the water cycle. Nitrogen and Phosphor compounds will be measured in the sampling stations along the river stream and they will be the basis for the exergy assessment. Understanding the successive Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 62 transformations of those compounds facilit ates the definition of the background parameters in the study. Being already concern about the human effects on water, next 2.5 section is devote to describe the main water uses (demand, consumption and quality), and to put them in relation with the existing water scarcity and degradation. 2.5. W ater uses, scarcity and deg radation Individual human bodies are 70% water. An average adult normally takes in two or three litres of water per day, mostly though drinking and eating. A similar amount is released mainly through urine, sweat and resp iration. People begin to feel thirsty after a loss of only 1% bodily fluids and risk death if fluid loss ne ars 10% (Bansil , 2004). These figures highlight how important is water for human life. However, water is used for many other purposes further than survival. Attending to the final water use in different world regions, the current water allocation can presented (Figure 2.14). There is in creasing competition for water among the various water use sectors in many river basi ns. When the water demand by industry is compared to the two other main sectors, it is evident that industry uses only a fraction of the amount of water used by agriculture. However, in East Asia and the Pacific, indust rial water use has grown to a significant proportion of total use, in line with its signif icance to the economies of those countries. In sub-Saharan Africa, although overall water use is low, the water used by industry is a larger proportion of the total, because more ag riculture is rainfed, rather than irrigated. These data exclude rainfed agriculture from the calculations of water use, and do not include environmental flow requirements as a water use category. In many catchment areas and river basins, environmental needs have not yet been calculated (UN-WWAP, 2006). 0 2 04 0 6 08 0 1 0 0 Oceania Nor th Am eri c a Cen tr al Am e ri c a South America Asi a Eur ope Afr i ca Wo r l d A gri cu l tural I ndust r i al Domest i c Figure 2.14. Water use by agricultural, do mestic and industrial sector s (Source: U N-WWAP, 2006) Withdrawal is defined as the removal of freshwater from water resources or reservoirs for use, while water consumption is understood as the use of water by humans from natural water resources or reservoirs for agriculture, industry or domestic purposes. Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 63 It is convenient to under line the return ra te associated to each water use, that is, the difference between the demanded catchment s and effective water consumed. Those water flows returned to surface and groundwa ter must be accurately depicted, in order to have the complete picture available. A rea listic water balance for a given river basin or country be then prepared. Analyses of recent trends show, that under con ditions of an increasing deficit in water resources, consid erable changes have been observed in World water management practi ces. These are associat ed, first of all, with the development of the price of water resources and the need to preventing environmental degradation (Shiklomanov and Rodda, 2004). These tren ds a re observed in charges in water use across the main sectors. Urban and industrial water uses do not represent high water consumption and their return factor is usually taken as 95-98% or even 100%. Nevertheless, some other more conservative sources indicate return rates of 90%, 86% and 30% respectively for industry, municipalities and agriculture (A lcamo et al., 2000; EPRI, 2002; Martínez- Beltrán and Koo-Oshima, 2004). In the simula tion model that will widely described in Chapter 6, no water consumption for these users has been assu med. Agriculture consumes more water by far than any other societal use. Water is needed by plants in photosynthesis to form carbohydrates, the basic food supply of all life. The case of agricultural uses is quite different because only a part of the irrigation water comes back to the same watershed. The return rate is high, but so is (generally speaking) the uncertainty about return pathwa y as well. In this work, 10% of return flow in the same watershed is considered. If the boundar ies of the analyzed system where enlarged, the complete IBC instead of isolated watersheds, the whole irrigation missed water could be better considered. The proportion of water used in each sector changes over time. While the vast bulk of water is currently withdrawn for and consumed in agriculture, an increasing proportion of water is being taken for urban and indust rial uses. Economic forces, and priority of uses in case of drought drive this switch (Shiklomanov and Rodda, 2004). The difference among water withdrawal and water consumption are shown in Figure 2.15, for the different water users. Figure 2.15. World water withdrawal and water consu m pt i on along the years, for differen t water uses (Source: UNEP, 2008) Following major growth between 1960 and 19 80, water withdrawal for use by industry worldwide has pretty much stabilized. Industrial water withdrawal in Europe has actually been dropping since 1980, although industrial output continues to expand. In Asia, the growth in industrial water withdrawal was rapid up to 1990, and has since then been Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 64 growing much more slowly, de spite the region’s high growth in manufacturing output. The intensity of water use in industry is incr easing in these regions, as is the value added by industry per unit of water used. In the industrial sector, the biggest share of freshwater is stored in reservoirs and dams f or electrical power generation and irrigation. However, one of the greatest cont ributions to water losses around the world is the volume of water evaporated from re servoirs. Industrial uses account for about 20% of global freshwater withdrawals. Of this, 57-69% is used for hydropower and nuclear power generation, 30-40% for indust rial processes, and 0.5-3% for thermal power generation (Shiklomanov, 1998). However, the biggest user of freshwater is the agricultural sector. It agriculture accounted for 67% of the world’s total freshwater with drawal, and 86% of its consumption. By the year 2000, approximately, the 15% of the world’s cultivated lands had been irrigated for food crops, accounting for almost half the value of global crop production (UNEP, 2009). Agriculture is expected to increase its water requirements by 1.3 time s, industry by 1.5 times, and domestic consumption by 1.8 time s, by 2025 (Shiklomanov, 1999; Alcamo et al., 2000). Freshwater use by sectors at the beginning of the 2000s is summarized in Figure 2.16. Figure 2.16. Freshwater use by sector at the beginning of the 2000s . (Source: UNEP, GRIDA, 2009) As a particular part in the industrial use of water, hydropower h as to be analyzed. Water is a key resource for energy generation, pr imarily through the use of hydroelectri c power, but also in nuclear-based energy ge neration, coal slurry technology and small scale hydroelectric schemes, among others. In 2000, one-third of the countries in the world relied on hydropower for more than half their electricity supply, and large dams generated 19% of electricity overall, although its importance varies from country to country. Twenty-four countries generate more than 90 percent of their electricity throug h hydropower, wher eas others generate none at all. In the developed world, roughly 70 % of hydroelectric power generati on potential has already been developed; in the devel oping world, only about 10% (WEC, 2007). Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 65 Europe makes use of 75 % of its hydropower potential, while Africa has developed only 7 percent (Figure 2.17). This is viewed as a possible cornerstone of Africa's future development, with significant export potential and plans to establish a continent-wide electricity grid. Hydropower brings flexibility to a national network grid, due to i ts ability to meet sudden demand. Run-of-river hydropower stat ions - from large to small - are clean, affordable and sustainable renewable energy providers. However, hydropower projects involving large reservoir construction fall into a different category. There remains considerable difference of opinion worldwide as to whether they should be classified as renewable energy and if they should be prioritized by de veloping countries for investment. Figure 2.17. Percentage of h y droelectrici ty generation of t he total by country . (Source:UN-WWA P, 2006) For hydropower, dams are needed. In 20 00, there were over 45,000 large dams worldwide (Figure 2.18). According to th e International Commission of Large Dams, a large dam is one with a height of 15 m or more from the foun dation, or a height of 5 to 15 m with a reservoir volume of more than 3 million m 3 . Half of the world’s existing large dams are built strictly for irrigation, while the remainders are built for hydro generation, water supply and flood control. Figure 2.18. Distribution of large dams wo rldwide. Shown as a percentage of total large dams worldwide. (Source: ICOLD, 2008). In the mid-1990s, there were 2,836 reservoirs with a storage capacity greater than 0.1 km 3 and a combined total volume of 6,384.5 km 3 . Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 72 Industries and water quality regulators in some places still rely on the so-called dilut ion effect to disperse contaminants within the water environment to the point where they fal l below harmful levels. In areas where industries are growing fast and more industrial plants are coming on-stream with many newl y created dischar ge points, this approach can quickly result in polluted rivers and reserv oirs. The toxicity levels and lack of oxygen in the water can damage or completely destroy the aquatic ecosystems do wnstream as well as lakes and dams, ultimately affecting riverine estuaries and ma rine coastal environments. In international river basins, routine pollution and polluting incidents such as industrial accidents and spillages may have transboundary effects. Significant pollution sources in river basins, such as large industrial plants, may be termed hot spots and prioritized for clean-up within a river basin management plant. Authors like Hernandez (2001) provide wide information about the change in water quality due to different industrial activities, depending on the productivity sector. Those figures will be used later on in this work to characterize the exergy degradation provoked by the different water uses. 2.5.1.3. Water use by agriculture Far more water is used b y agriculture than by any of the other sectors and most of this water is employed for irrigation. The demands of irrigation can place water resources under stress, particularly in dry years. a. Water demand in agricultural use The bulk of the world’s agricultural produ ction is rainfed, not irrigated (Shiklomanow and Rodda, 2004). Claims that agricultural production is threatened by global water shortages usually fail to note that most of the world’s food production does not rely on freshwater withdrawals at all and does not n ecessarily accelerate the naturally occurring rates of evapotranspiration. The largest share of the water uptake by plan ts is transpired back into the atmosphere through plants’ leaves. In addition to its energy dissipating role, the transpiration process is necessary for lifting nutrients from -photosynthesis takes place. If soil moisture levels fall below the wilting point, plant growth slows and eventually stops, and the potential crop yield is not fulfilled. Irriga tion aims at ensuring that enough moisture is available at all times during the plant’ s life cycle to satisfy its water demand, thus supporting maximum crop yields. The concept of blue and green water has been used for quite some time to distinguish between two fundamentally different elements of the water cycle (see section 2.2). When atmospheric precipitation reaches the ground, it divides into several sections, which pursue the terrestrial part of the hydrologic al cycle along different paths. Out of a total annual amount of 110,000 cubic kilometres (km 3 ) of precipitation on the land surface, about 40,000 km 3 is converted into surface runoff and aquifer recharge (blue water) and an estimated 70,000 km 3 is stored in the soil and later returns to the atmosphere through evaporation and plant transpiration (green wa ter). Blue water is the freshwater that sustains aquatic ecosystems in rivers and lakes; it can also be applied to drinking or domestic purposes, to industry or hydropo wer or to irrigated agriculture (UN-WWAP, 2006). Rainfed agriculture uses only green water. Irriga tion uses blue water in addition to green water to maintain adequate soil moisture levels, allowing the cr op plants to absorb the Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 73 water and fulfil their crop yield potential. The green water /blue water concept has proven to be useful in supporting a more co mprehensive vision of the issues related to water management, particularly in reference to agriculture (Ringersma et al., 2003). It is estimated that crop production takes up 13% (9,000 km 3 per year) of the green water delivered to the soil by precipitation, the remaining 87% being used by the non- domesticated vegetal world, including forests and rangeland. Out of the world’s total land area of 13 b illion hectares (ha), 12 percent is cultivated , and an estimated 27 percent is used for pasture. The 1.5 billion ha of cropland include 277 million ha of irrigated land, representi ng 18 percent of cr opland. In population terms, cropland amounts to a global average of 0.25 ha per person (UN-WWAP, 2006). Figure 2.19 shows the evolution of cropland compared to population between 1960 and 2000, illustrating the huge productivity increa se of agriculture during that period. The intensification of agricultural production ma de it possible to limit the expansion of agricultural land to a few percentage poin ts as the population was more than doubling. Figure 2.19. Evolution of cropland, 1961–2000 (source: FAOSTAT, 2005 cited by UN-WWAP, 2006) During the twentieth century, the World popula tion multiplied by three. At the same time, water used in irrigation increased sixf old. It was accompanied by the almost depletion of some major rivers. Specific management tools related to improved high- yielding varieties of cereals, irrigation, improved soil mois ture utilization and the application of plant nutrients, pest c ontrol, where the talents of the named green revolution. As a result of those technology pack ages on good land in suitable socio- economic environments, the crop yields increased, as well as the incomes for millions of farmers, particularly in Asia. Statistics in dicate that yields of rice, wheat and maize approximately doubled between the 1960 s and the 1990s (UN-WWAP, 2006). The green revolution meant an important development, but it h ad also a negative face: fertilizers and agrochemical, based pest an d weed control created environmental and health problems. Along the second half of the twentieth ce ntury, while population rapidly increased, irrigation development became a cor e part of the strategy produce food. It meant, consequently an increase in the water consumption. As the food needs i ncrease, the Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 74 amount of land for agriculture is expected to grow. However, land has to be both suitable and available for conversion to ag riculture. So, the options are limited. b. Water consumption in agricultural use While irrigation currently withdraws about 2,300 km 3 of freshwater per year from rivers and aquifers, only about 900 km 3 is effectively consumed by crops. As previously indicated, it represents about 60-70% of the water demand and 90% of the water consumption (Alcamo et al., 2000). Rather than water use efficiency, the con cept of water productivity is now widely accepted as a measure of performance in agricultural water use. By definition, productivity represents the output of any production process expressed per unit of a given input, in this case water. In agricultur e, several types of output can be considered. In a strict commodity production vision, the ou tput is usually expressed in volumes or value of a given agricultural production. However, productivity calculations are increasingly being extended to assess the water value of other outputs, including the social and environmental services prov ided by irrigation (Molden et al, 2003). c. Water quality in agricultural use It is quite difficult to define average values for the change in quality due to irrigation. It mainly depends on the kind of soil and on th e crop. As an exampl e, the more than 100,000 ha irrigated by the Bardenas Canal that or iginates in the Yesa Reservoir located in the Aragón River has an irrigation wa ter of excellent quality (EC=0.32 dS/m; NO 3 - <2 mg/l) (Causapé et al. 2004) Isidoro et al (2002) characterized the qua lity of drains water. The waste waters were characterized using an average small value conductivity (0.84 dS/m) and high nitrate concentration (54 mg/l). On the other hand, the values of some rivers used a higher average conductivity (0.9 7 dS/m) and a much more smaller nitrate concentration (27 mg/l). Water that is available for reuse after application in irrigation often carries concentrations of agricultural pollution that render it unfit for many application –even for reuse in growing crops (Hunt, 2004). Wastewater and water desalination constitute pot ential sources of water for agriculture and other uses. Technologies for tertiary wa stewater treatment and desalination have very much in common. However, the cost of treatment varies depending on the type of treatment and the intend ed final use of product water. Treated wastewater reuse in agriculture is less expensive than is desalinated water. With its associated benefits, treated wastewater reuse also has problems in terms of public acceptance, and potential health and environmental risks. Although the WHO and FAO have specified guidelines for wastewa ter reuse, no common standards have been set owing to difficulties in systematic implementation in countries around the world. For the reasons above, due consideration should be given to both the problems and benefits of wastewater reu se and water desalination. Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 75 The experts recommended wastewater trea tment as a better option in sustainable development and the introduction of programme s to inform the public of the benefits of treated wastewater reuse. The group also su ggested that hybrid solutions, a blend of wastewater plants coupled with desalination plants, may have a place in urban and peri- urban agriculture. However, of great importance is the setting of standards for the outflow quality of wastewater treatment plants and the associated effluent monitoring. In relation with the suitability of desalinated water for crops, the Irrigation Water Salinity Index (IWSI) is defined by Cánovas (1986) . Eq. 2.5 . [ ] [] [ ] 2 2 2 + + + = Mg Ca Na IWSI From Eq. 2.5, it can be concluded that a desalinated water have to be used carefully for crops. Since desalination efficiency is usually less than 100%, the remaining ions would be probably the Na + (the smallest ones). Then, the IWSI would be infinity because the equation becomes [Na + ]/0. On top of that, desalinated water is more expensive than con ventional water resources and it is not affordable for most crops, alt hough it might be affordable for high value crops, especially where subsidies on capital costs are provided. Continuing with cost considerations, bracki sh water desalination is more suitable for agricultural production than is seawater de salination. Moreover, desalination facilities near the point of use are preferred in order to minimize transfer costs. In terms of operation and maintenance (O&M), s mall to medium plants are more problematic. Finally, if desalinated water is used for agri culture, reverse osmosis (RO) is the best desalination technology because of the cost reductions driven by improvements in membranes in recent years. Spain provides a significant example of the application of desalinated water in irrigation. Spain has more than 300 treatment plants (about 40 percent of the total number of existing plants) and 22.4 percent of the tota l desalinated water is used for agriculture. Most of these plants process brackish water (only 10 percent of the total desalinated water for agriculture originates from seawater ) and are located in coastal areas or within 60 km of the sea (Martínez and Koo-Oshima, 2004). In this co untry, small and medium- sized brackish-water desalination plan ts, with a capacity of less than 1,000 m 3 /d, are common because they adapt better to individual farmer requirements and to the existing hydraulic structures. Desalination programmes are recommended to be integrated with water resources management, with application of best pr actices for water management (leaching requirements, and better irrigation methods) and selection of appropriate salt-tolerant crops. The optimal size and site of facilitie s should be studied, and better operating management of smaller plants is require d (automatic plant operations, and farmer knowledge on operational processes). Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 76 2.5.2. Summary of quality for diverse w ater uses Two main water quality parameters (conduc tivity and TOC) for different uses are collected in Table 2.14, in which the most re levant information in relation with previous sections has been summarized. Input water values (before use) and output water values (after use) can be shown in it. C (ppm) COD (mg/l) Dom.Low.in 32 50.75 Dom.Low.out 100 181.81 Dom. Medium in 32 50.75 Dom. Medium out 200 363.63 Dom. High in 32 50.75 Dom.High out 500 545.44 Irrig. None in 448 34.13 Irrig. None out 2,989 61.09 Irrig. Moderate in 1,000 34.13 Irrig. moderate out 6,400 61.09 Irrig. Severe in 1,920 34.13 Irrig. Severe out 12,800 61.09 Energetic in 1,920 140.0 Energetic out 2,240 232.7 Ind. Salt extract. In 960 50.8 Ind. Salt extract. Out 150 15,185 Ind. Gas product. In 960 50.8 Ind. Gas product. Out 937 272.7 Ind. Plastic in 960 50.8 Ind. Plastic out 50 45.4 Ind. Wash-mach. In 960 50.8 Ind. Wash.-mach.out 7,400 7,273 Paper Industry in 960 50.8 Paper Industry out 20 25.5 Fruits and veget. In 32 50.8 Fruits and veget. Out 1,944 5.5 Animal waste In 960 50.8 Animal waste Out 1,000 5,908 Ind. soap In 960 50.8 Ind. soap out 333 6,062 Table 2.14. Chemical featur es of the water befor e and after diffe rent common uses . (Sources: Metcalf and Eddy, 2003; Hernández, 2 001; Causapé et al., 2005.) Domestic input water quality param eters (potable/drinkable water para meters) are standard, irrespective of the kind of population nucleus. However, more output contamination/pollution can be considered in the urban ones. On the other hand, irrigation water values ha ve been divided into three groups, using different degrees of use restriction, sin ce it is the most common standard quality Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 77 parameters division found in bi bliography. On top of that, many examples of different crops are available, and their individual study seems to be endles s. Because some of the most problematic output irrigation water parameters are conductivity, or nitrates, the TDS increments a re very high, and the TOC can be considered almost constant. Energetic water use (for coo ling water or steam generation) input parameters are shown less restrictive than the preceding ones. Finally, some examples of different industrial uses are included. Fr uits and vegetables industry input parameters are the same as the domestic ones, since this kind of industry is a food manufacturer. Recall that in some industrial uses examples, output conductivity is bigger than input conductivity. Nevertheless, it can be assured th at this is a coherent affirmation in some of them, for instance, the salt extraction industry example. 2.6. W ater demand mana gement A basic idea within the water management world, is the distinction between supply enhancement and deman d management. Whenever water demand exceeds water supply, there are two general methods for addressing the problem: it may be either carry ou t alternative designed to enhance water supply, or pursue approaches meant to con trol and manage demand. The first harnesses anothe r water source in some way, and the second invokes ways to operate within the lim its of current supplies (Griffin, 2006). Of course, we can jointly undertake both types of measures, and this is normally best. Examples within each category are listed in Table 2.15. Supply Enhancement Strategies Demand Man a gement Strategies Establish water-conserving plumbing codes requirin g certain fixture typ es Build/enlarge dams (such as low-flow toilets and showerheads) Drill/imrove wells Establish contingency plants Build interbasin water tran sfer facililities Ration water or constrain water use Repair leaky infraestructu re Buy/Lease/sell water rigths Build desalination plants Raise water rates Reprogram reservoir operations Educate population a bout conservation options Table 2.15. Supply and demand strategies. (Source: Griffin, 2006) Supply enhancement has dominated water resource planning in the modern era, but this dominance has been suspended in many developed countries. Traditional forms of supply enhancement have run much of their course, because fresh water supplies are physically limited. New dams and wells genera lly deprive water from some existing or future category, even if it is estuary inflow s, which have become increasingly valuable due to great amount of human diversions of water from its natural courses. Moreover, Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 78 these forms of supply enhancement a re much more expensive than they have been in the past. As the role for supply enhancement has ebbed, the opportunities of demand management have simultaneously increased. While individual demand management options lack the scales of supply enhancement facilities, and they are certainly not viewed as the monuments to human achievement that our da ms have become, demand management strategies are powerful tools for balancing demand and supply. Conserving available water and reducing dema nd is a necessary measure in water-short regions, especially those in arid climates. Water deman d management (WDM) programmes select economic incentives to efficiently promote the respo nsible water use; they identify water conservation measures aimed at raising society’s awareness of the resource. Such tendency differs from th e traditional supply driven method, which makes all existing water available. In those places where water was traditionally perceived as abundant, no WDM programmes have been implemented. Nevertheless, the benefits in the extended useful life of water supply and treatm ent plants and in the operating ef ficiency and duration of sewage disposal systems can be considerable in terms of higher economic return on investment (UN-WWAP, 2006). Water demand management meant to be the strategy that stresses on making better use of water already mobilised, thanks to a reduction in physical and/or economic waste. Typical phases when strategy is to be applied are: flow control, loss control, supply versus demand policy, metering, pricing, training, legislation, etc. The increasing scarcity of water sources to meet societal demands is transl ated into the inclusion of planned water reclamation, recyclin g, and reuse in water resources systems. WDM advocates a wide range of measures th at go beyond conservation to broader sustainable resource management. It applies to the protection of water quality sources; reduction of wastage both in infrastructure leakage and by users; improvement of water allocation among competing uses, and creati on of appropriate pricing mechanisms. One example of a situation where conservation measures are needed is the case of undelivered water, a commonly accepted result of utilities su pplying water through piped distribution systems: losses are routinely reported as 40% and as high as 60 to 70% in some major cities (UN-WWAP, 2006). By reducing leakage and demand, substantial reductions in th e source volumes could be achieved. This should be a clear message in development settings. WDM may obviate the need for some of the proposed large-scal e physical or infrastructure investments and thereby provide real efficiency gains to society (G WP, 2005a). In the management of a sustainable industry s ector, it is crucial the integration of water management. In addition, such a practice links environmental and economic outcomes. The management will very much depend on the activity, although water is present in an important amount of processes. In ge neral, the most common actions to be implemented within the water consumption are the water bal ance, the environmental audits and the operational performance reviews. They all can help operati onal sites to Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 79 develop specific solutions; the identification of the best technology to improve the process is fundamental. Industry pays for potable water at processing plants and it generates wastes that pollute it. Reduction of water use through stro mwater collection, general recycling or reclamation of used water is an appropriate method to reduce cost and water usage. Agriculture and irrigation, the main water use r sector on a global scale and there exist an increasing pressure for water to be used more efficiently. Demand reduction and modernization of irrigation systems are basic actions that a re being implemented in agricultural water management. 2.7. W ater suppl y technolo gies The world’s population growth will mean an increased need for water to meet various needs, as well as an increased production of wastewater. In addition to the common water supply from surface waters and aquife rs after a proper treatment process, desalination and reuse are starting to play an important role in modern water supply systems. In the following, a review of the current available techn ologies is developed. It is quite relevant to highlight that each op tion has to be carefully analyzed within its boundary conditions, specially its location and surrounding infrastructure. Many communities throughout the world are a pproaching, or have already reached, the limits of their available water supplies; water reclamation and reuse have almost become necessary for conserving and extending available water supplies. 2.7.1. Water treatment plants Two different types of water treatment plants, the most common ones, are considered here: plants for water potabilization and wastewater treatment plants. 2.7.1.1. Potable water plants The first step in acquiring safe drinking water is to protect raw water at its source. Watersheds used for municipal water sour ces often have restricted land uses, recreational activities, and development contro ls. Water providers must limit erosion of sediments, body contact sport such as swimming and water skiing, and waste disposal in such areas. The second step in acquiring drinking water is t o d i v e r t i t f r o m a river, reservoir, or groundwater. Intakes are the permanent conne cting structures (pies, cement conveyance structures, etc.) that capture raw water and transport it to a drinking water treatment facility. The intake of a groundwater well incl udes the screened well casing in the aquifer and a piping system that delivers groundwater to the trea tment land or end user. The intake for surface water sources can include a diversion dam and head gate on a river, or pipes that divert water from a reservoir. Water intakes at reserv oirs are usually located at different depths to obtain varying water temperatures and suspended sediments. Intakes Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 80 are generally not placed near the water surface to avoid floating debris, or at locations that could collect bottom deposits. Drinking water sources can be i ntermingled to improve the temperature and water quality of raw water provided to the treatment plant from multiple sources. Pretreatment In pre-treatment of drinking water, once raw water is delivered to a water treatm ent plant through an intake pipe, pre-treatmen t usually occurs in large tanks or small reservoirs where a variety of water treatmen t steps begin. Pretreatment i s particularly useful if water is diverted from a river that has high amounts of suspended sediments. Screens are fist used to remove large floating items, fish, fine solids, and other objects. Next, water is allowed to stand in tanks or reservoirs to promote sedimentation whereby larger silts, fines, and clay particles settle out of suspension. Afterwards, treatment starts. Treatment The steps considered in the treatment are: flocculation/coagulation, filtration and the final drinking water treatment. The sources consulted for the elaborati on of this treatment summary were, mainly, the works of Cech (2003), Metcalf and Eddy (2003), Klein et al. (2005) and Surampalli (2004). a) Flocculation/coagulation. It is the next step in drinking water treatmen t, and is the process of adding chemicals to water to cause very fine suspended matter to settle out. Chemicals, such as aluminium potassium sulphate, activated silica, clay, and soda ash have been found to assist in this process when agitated (flash mixing) into raw water. A precipitate of almost gelatinous particles will usually coagulate within 10 to 30 minutes after the chemicals are added. This coagulation of fine suspended matter is called flocculati on and will gain enough mass and weight to settle out of the water as sludge. The main objective of flocculation and coagul ation is the formation of cl ear water that has flocculation visible and in suspension. This process can remove approximately 90 to 99 percent of all viruses present in water, although prechlorination and preozonation may be necessary if excessive organic material is present. Viruses are not actually killed during this process; instead they are contai ned within the settled floc a nd sediments, which are later removed. Concrete or steel sediment basins, generally 2.4 to 6.1 m deep, are used to hold water during the flocculation/coagulation pro cess. Pretreated water continuously flows through these tanks. Sludge, created by sett ling flocculation, is generally removed from the bottom of the sediment basins every six months. b) Filtration Filtration follows flocculation and coagulati on, and is the process of passing water through layers of sand and gravel to eliminate turbidity, odour, and colour. The most common method of filtration is the gravity ra pid sand filter in which water is passed through beds of sand. Some drinking wa ter plants can eliminate the need for flocculation and coagulation if the raw wate r is obtained from protected (clean) sources of surface or groundwater. Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 81 Filtration is a relatively simple process. Ra w or pretreated water is slowly sprayed or sprinkled onto filtering media (sand). Gravi ty forces water through the sand particles until it exits the bottom of th e media: Filtered water is conveyed to a stora ge area for additional treatment (pH, fluo ridation, and disinfection). Filters can become clogged with sediment s and other particulates, and must be backwashed (flushed) occasionally to remove u nwanted materials. The backwashed material is considered waste and must be drained into the sewer system for treatment before being released back to rivers, lakes, or other water bodies. Improper backwash techniques can allow pollutants to contaminate a drinking water system. c) Final Drinking Water Treatment Alter filtration is completed, water is placed in holding basins where fluoridation, and disinfection can occur. Fluoridation is cons idered a preventive medicine program to improve the health of teeth. Sodium fluoride (NaF) is generally used in this process. Chlorine gas is a common method of disinfection, called chlorination. The gas is mixed with water to kill remaining bacteria and some viruses. Chlorine odour and taste are com mon complaints of drinking water customers; activated carbon treatment can help reduce these complaints. Since chlorine is very toxic, safe storage and handling of the chemic al at water treatment plants are extremely important. Chlorine compounds were used as early as the 1830s to eliminate foul smells. Ozone gas and ultraviolet (UV) systems may al so be used in this final stage of water treatment to eliminate remaining bacteria and viruses. Ultraviolet tr eatment kills almost 100 percent of all microbiological organisms in water, but it is a very slow and expensive process. pH and corrosion control also occur at this stage of drinking water treatment by adding chemical such as lime and soda ash. However, it is necessary to add an excess of 0.3-0.5 mg/L of chemical substances, b ecause of its evaporati on in the urban supply circuit, and its necessary to use chlorine, since O 3 leaves water a nd does not persist time enough into the water which is being supplied using pumps. The Council Directive 75/440/CEE, mentioned pr eviously, includes, in its attached 2, quality values required for surface fresh water intended for the abstraction of drinking water in the Member States of forty-six water parameters (as colour, temperature, NO 3 - , Fe 2+ , or Cl - ). Three water quality levels are defined. Leve l A1 (very high quality waters), A2 (medium quality waters) and A3 (low quality waters). Ea ch of them includes different treatment and phases, which are summarized in Figure 2.20, for A1 and A2. Intensive treatment, A3, is similar to A2 treatment scheme. However, includes two steps of oxidation, before the mix chamber and after the sand filters. Drinking water treatment facilities are generally located at the highest topographic location in a city to allow treated drinking water to be delivered to customers by gravity. A1 water treatment: Solids Elim . Sand Filters Waste wat er i Final Desinfect Storage Fresh water Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 88 Figure 2.23. Reclamation and reuse facilities in the cyc ling of water through the hydrologic cycle (Source: adapted from Asano and Levine, 1995). 2.7.2.2. Wastewater reuse applications In the planning and implementation of water recla mation and reuse, the reclaimed water application will usually govern the wastewater tr eatment needed to pr otect public health and the environment, and the degree of relia bility required for the treatment processes and operations. In general, water reuse app lications fall under one of five categories. The relative amount of water used in each category varies locally and regionally due to differences in specific water use require ments and geopolitical constraints. In Spain, the criteria of reused water ut ilization are defined in the R.D . 1620/2007 ( REAL DECRETO 1620/2007, de 7 de diciembre, por el que se establece el ré gimen jurídico de la reutilización de las aguas depuradas ). The existing categories ar e: urban uses, agricultural uses, industrial activities, recreational uses and environmental uses. i) Urban uses include fire protection, air conditi oning, toilet flushing, construction water, and flushing of sanitary sewers . Typically, for economic reasons, these uses are incidental and depend on the proximity of the wastewater reclamatio n plant to the point of use. In addition, the economic advantages of urban uses can be enhanced by coupling with other ongoing reuse applications such as landscape irrigation. ii) Agricultural use represents the largest current use of reclaimed water throughout the world. This reuse category offers significant future opportunities for water reuse in both industrialized countries and developing countries. iii) Industrial activities represent the third major use of reclaimed water, primarily for cooling and process needs. Cooling water creates the single largest industrial demand for water and as such is the predominant industrial water reuse either for cooling towers or cooling ponds. In dustrial uses vary greatly and water quality requirements tend to be industry-specific. To provide adequate water quality, supplemental treatment may be required beyond conventional secondary wastewater treatment. Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 89 iv) Recreational uses involve non-potable uses related to land-based water features such as the development of recreational lakes, marsh enhancement, and stream flow augmentation. Reclaimed water impoundments can be incorporated into urban landscape developments. Landscape irrigation is the second largest user of reclaimed water in industrialized countries and it in cludes the irrigation of parks; playgrounds; golf courses; freeway medians; landscaped areas around commercial, office, and industrial developments; and landscaped areas around residences. Many landscape irrigation projects involve dual distribution systems, which consist of one distribution netwo rk for potable water and a separate pipeline to transport reclaimed water. v) Environmental use constitute the fifth largest use of reclaimed water in industrialized countries . Reclaimed water has been applied to wetlands for a variety of reasons including: habitat creation, restoration and/or enhancement, provision for additional treatment prior to disch arge to receiving water, and provision for a wet weather disposal al ternative for reclaimed water. Falling under this use, groundwater recharge is the fourth largest application for water reuse, either via spreading basins or direct injection to groundwater aquifers. Groundwater recharge includes groundwater replenishment by assimilation and storage of reclaimed water in groundwater aquifers, or establishing hydraulic barriers against salt-water intrusion in coastal areas. Potable reuse is another water reuse opportuni ty, which could occur either by blending in water supply storage reservoirs or, in the extreme, by direct input of highly treated wastewater into the water distribution system. However, according to the R.D. 1620/2007 (Art.4), this use is prohibited. Only in the case of a disaster water could be use, previously defined the quality parameter values by the sanitary authorities. On top of that, because of the costs of treatment and sa fety concerns, water reuse applications have been limited prim arily to nonpotable uses. However, some communities are continuing to investigate and ev aluate the potential for indirect an d direct potable reuse options. While the quantities of reclaimed water involved in these potable water reuse projects are small, the tech nological, public health, aesthetic, an d public acceptance issues are of fundamental importance and are a greater challenge in water than in drinking water supply. While potentially large quantities of reclaime d municipal wastewater can be used in th e first five categories, the quantities associated with the sixth and seventh reuse categories are minor at present; particularly potable water reuse. Some water reuse examples are summarized in Table 2.16. Application settings Examples Urban use Unrestricted Landscape irrigation (parks, playground s, sch ool yards), fire protection, construction, ornamental fountain s, recreational im poundments, in- building uses (toilets, air conditioning) Restricted-access irrigation Irrigation of areas where public acce ss is infrequen t and controlled (golf courses, cemeteries, resi dential, greenbelts ) Agricultural irrigation Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 90 Application settings Examples Food crops Crops grown for human consumption and consumed un cooked Non-food crops, food crops consumed afte r processing Fodder, fibre, seed c r ops, pa stures, commercial nurs eries, sod farms, commercial aquacul ture Recreational use Unrestricted No limitations on body contact (lak es and ponds used for swimming, snowmaking) Restricted Fishing, boating, and othe r non-contact recreational activities Environmental use Artificial wetlands, enhanced natural wetlands, an d sustained stream flows Groundwater recharge Groundwater replenishment, saltwate r intrusion control, and subsidence control Industrial reuse Cooling system makeup w ater, pr ocess waters, boiler feed water, construction activities, and washdown waters Potable reuse Blending with municipal water suppl y (surface wa ter or groundwater) Table 2.16. Reuse examples. (Source: Levine and Asano, 2004) 2.7.2.3. Treatment and Water Quality Considerations Understandably, the construction of r eclaime d water transmission and distribution lines to existing users in large cities is expe nsive and disruptive. As a result, wastewater reclamation and reuse will continue to be mo st attractive in serving new residential, commercial, and industrial areas of a city, where the installation of dual distribution systems would be far more economical than in already developed areas. Use of reclaimed water for agricultural purposes near urban areas can also be economically attractive. Agricultural use rs are usually willing to make long-term commitments, often for as long as 20 years, to use large quantities of reclaimed water instead of fresh water sources. One potential scenario is to develop a new reclaimed water system to serve agricultural need s outs ide the city with the expectation that when urban development replaces agricultural lands in time, reclaimed water use can be shifted from agricultural to new urban development. Water reclamation and non-potable reuse typically require conventional water and wastewater treatment technologies that are al ready widely practiced and readily available in many countries throughout the world. Whe n discussing treatment for a reuse system, the overriding concern continues to be wh ether the quality of the reclaimed water is appropriate for the intended use. Higher level uses, such as irrigation of public-access lands or vegetables to be consumed wit hout processing, require a higher level of wastewater treatment and reliability prior to reuse than will lower level uses, such as irrigation of forage crops and pasture. For ex ample, in urban settings, where there is a high potential for human exposure to reclaimed water used for landscape irrigation, industrial purposes, and toilet flushing, the reclaimed water must be clear, colourless, and odourless to ensure that it is aesthetically acceptable to the users and the public at large, as well as to assure minimum health risk. Experience has shown that facilities producing secondary effluent can become water reclamation plants with the addition of filtration and enhanced disinfection processes. Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 91 A majority of the states have published treatment standards for guidelines for one or more types of water reuse. Some of these states require specific treatment processes; others impose effluent quality criteria, and so me require both. Many states also include requirements for treatment reliability to prev ent the distribution of any reclaimed water that may not be adequately treated because of a process upset, power outage, or equipment failure. Dual distribution systems (i.e., reclaimed water distribution systems that parallel a potable water system) must al so in corporate safeguards to prevent cross- connections of reclaimed water and potable water lines and the misuse of reclaimed water. For example, piping, valves, and hydr ants are marked or colou r-coded (e.g. purple pipe) to differentiate reclaimed water from potable water. Backflow preventio n devices are installed, and hose bibs on r eclaimed water lines may be prohibited to preclude the likelihood of incidental huma n misuse. A strict industrial pre-treatment program is also necessary to ensure the reliability of the biological treatment process b y excluding the discharge of potentially toxic levels of pollutants to the sanitary sewer system. Wastewater treatment facilities receivi ng substantial amounts of high-strength industrial wastes may be limited in the number and type of suitable reuse app lications. Differences are also apparent in the distri bution of reclaimed water for these different purposes. Where disposal is the objective, meters are difficult to justify, and reclaimed water is often distributed at a flat rate or at minimal cost to the users. However, where reclaimed water is intended to be used as a water resource, metering is appropriate to provide an equitable method for distributing the resource, limiting overuse, and recovering costs. Until this point, the sections 2.7.1 and 2.7.2 have covered the issues related to the water treatment plants main features and the existing water reuse technologies. In addition to treat the used water for giving it back to the ri ver, or for directly reusing it, an alternative water source is obtaining fresh water from the seawater. It is an initially expensive option, but the feasibility of each study has to be study befor e judging it; the suitability of the desalination option will always depend on the comparing factors. In the next section 2.7.3, the most relevant desalination option s are summarized. 2.7.3. Desalination as a new w ater suppl y technology. Desalination technologies are currently a solu tion to obtain a healthy freshwater under cost and environmental optimum conditions. On top of that, some places have been highly developed (e.g the Persian Gulf) because of their fossil fuels abundance. Desalination can be achieved either by removi ng salt from water, or by r emoving pure water from a saline or polluted source. For producing large quantities of freshwater from a saline source, it is necessary to re move the water from the salt. This process leaves behind a highly concentrated s aline solu tion, or brine, which must be disposed of as a waste product, often in the sea. Two desalination methods are in common use : thermal and membrane separation. The general desalination process is schematized in Figure 2.24. Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 92 Figure 2.24. The desalination process There are two main phase-change separation meth ods. In the first, the most common desalination process, water is evaporated an d the vapour is condensed. An alternative consist on freezing the water and melting of ice crystals. Evaporation can be carried out by bringing wa ter in contact with a hea t transfer surface (boiling process, for exa mple, MSF, MED, SEE-VC, humidification-dehumidification, and a number of methods based on the use of s olar energy) or bulking feed water ( to produce vapour through what is termed a flashing process). To improve thermal efficiency, vapour compression is combined with desalination processes. In the VC process, low temperature vapour formed in the same effect or the preceding evaporation effect is compressed and used to initiate the evaporation process in the first or the same evaporation eff ect. The VC process incorporates component devices that include mechanical compresso rs, steam-jet ejectors, TVC components, adsorption/desorption beds, and absorption/desorption columns. Variants of the single effect VC process include mechanical vapour compression (MVC), ther mal vapour compression (TVC), absorption vapour compression (ABVC), adsorption vapou r compression (ADVC), and chemical v apour compression (CVC). On the other hand, membrane desalination pr ocesses, in which a highly concentrated brine stream is formed on the other side of the membrane, include Reverse Osmosis and Evaporated Distillation. In the RO process, high pressure forces fresh water to permeate through a semi- permeable membrane, leaving behind a high ly concentrated brine solution. ED is activated using electrical energy, causing electr ically charged salt ions to move through selective ion exchange membranes, leaving behind low salinity product water . An overview of the main desalination ca tegories is summarized in Figure 2.25. Traditionally, thermal desalination or distillation has been the most commonly used technology for producing large quantities of freshwater from seawater. Different thermal desalination processes require differe nt magnitudes and combinations of heat and electricity. The economic efficiency of de salination plants is improved by combining the purposes of power and water production. Most of the desalination plants operating in the Middle East and elsewhere are dual-p urpose multistage flash distillation plants that produce both water and electricity, using oil as the energy source. However, oil price rises undermine the economic performan ce of these plants, even in the Arabian Gulf region. As a result, nuclear power is increa singly being considered as a viable energy source for thermal desalination plants, particularly in countries that have local Feed Water Brine Fresh water energ y Separation Unit (membrane or thermal ) Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 93 uranium reserves. The advantages include fuel price stability and the long-term availability of the fuel, but these need to be balanced against the well-known drawbacks of high initial investment costs and the disposal of spent nuclear fuel. Figure 2.25. Desalination processes schema . (source: ESCWA-UN, 2001a). . On the other hand, the freezing desalination was extensively developed in the 1950s and 1960s. It has some advantages which include lower theoretical energy requirements and limited corrosion, scaling and salt precipitation in plant components. However, the process involves dealing with ice and wate r mixtures that are mechanically rather difficult to handle. During the freezing, dissolved salts are excl uded from ice crystals. Before the entire mass of water has frozen, the mixture is usua lly rinsed to remove the salts in the remaining salt-laden water adhering to the i ce crystals. The fresh ice is then melted to produce fresh water. Desalination development is enormous. No wadays, its installed capacity is 47 Mm 3 /d (more than the urban consumption). Expected desalination average growing by 2005- 2015 is 101%, with a maximum value in Mediterranean region (179%). Ninety-seven percent of the world’s water is too salty for consumption or agriculture. Desalination is not a new concept, as it has been practised since biblical times. However, the process typically consumes large quantitie s of energy in o rder to produce drinking water from seawater or polluted water, making energy cost the major deter minant of the desalination cost. Hence desalination technolog y has tended to be used in water-scarce countries where energy is cheap and plentiful. Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 94 As of June 30, 2008, there were 13,872 “contracted desalination plants” worldwide, according to Global Water Intelligence and th e International Desalination Association. As Table 2.17 indicates, an important percentage of the world’s desalination plants are located in the Arabian Gulf Countries. COUNTRY m 3 /d % of the world desalted water Saudi Arabia 10,759,693 17% United Arabia Emirates 8,428,456 13% USA 8,133,415 13% Spain 5,249,536 8% Kuwait 2,876,625 5% Algeria 2,675,958 4% China 2,259,741 4% Katar 1,712,886 3% Japan 1,544,849 2% Australia 1,493,158 2% Table 2.17. Top ten desalination countries (Sou rce: EMIS, 2008 and GWI-IDA, 2008) Desalination in the Middle East usually comes in the form of thermal processes: MSF & multi-effect distillation (MED). This is mainly due to the low cost of energy in these countries and the problems faced by membrane processes in dealing with the high salinity of the Arabian Gulf water. The desalination market in the Middle East and North Africa, is expected to increase significantly as drought conditions worsen, populations grow and water demand per capita increases due to expansion in industrial activities and development of tourism. In Europe and in most of the rest of the world, the dominant technol ogy is RO. Reverse osmosis has seen the most rapid growth in the last 30 years mainly due to technological developments in the membrane manufacturing process. The advantages of RO are that it is an economical process that consumes little energy. The low investment and operation costs of this widely accepted technology add to its appeal. All major desalination technologies have de monstrated their ability and reliability to produce fresh water in an economical ma nner. Each technology has found their supporters and users, stimulating competiti on between them and provoking the continuous improvement of all of those technologies. According to the experts, the best desalin ation technologies are distillation (multistage flash, MSF) and membrane technologies (r everse osmosis, RO, and reversal electro- dialysis, EDR). RO and EDR are applied to desalinate brackish water, with salt concentrations of less than 10 g/litre, while RO and distillation are applied for seawater, with a salt concentration of more than 30 g/litre. The percentage and desalinated water produced volume by technology are summarized in Figure 2.26. Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 95 ED 4% 2,220, 1993 m 3/d MED 10% 6,029,368 m 3/d MSF 27% 17,300, 196 m 3/d RO 56% 37,066,56 8 m /3d Figure 2.26. Contracted desalination plants by technology. (source: GWI, 2008) The increase in contracted MED capacity sinc e 2004 have been a 103 %, and nearly 3.1 Mm 3 /d of capacity was contracted between the end of 2004 and mid-2008 (GWI, 2008) The experts recommended that each specific ca se be studied carefully before selecting the technology. The expert group designed by FAO considered membrane technologies as being most adaptable with EDR being promising for future applications. (FAO, 2006) Different feedwater qualities and off-takers of desalinated water are summarized in Figure 2.27 and Figure 2.28. Seawat er 63% 39,405,669 m 3/d Ri v er W at er 8% 4,883,41 3 Pur e W at er 5% 3,610,598 Br a ckish W at e r 19% 12,227,673 m 3/d Wa s te Wa te r 5% 3,239,241 m 3/d T ouris m 1% 890 , 261 m 3/d Ind u s t rial 23% 14,314,969 Ir rigat ion 2% 1,100,066 M ilit a r y 1% 603,758 Muni ci pal 67% 42,441,086 Pow er 6 % 3,707,703 Figure 2.27. Feed water quality of desalination plants. (source: GWI, 2008) Figure 2.28. Off-takers of desalination plants. (source: GWI, 2008) 2.7.3.1. Distillation thermal processes Industrial thermal desalination was greatly developed with the introduction of submerged evaporators. The tubes of submerg ed heating steam evaporate feed water, as salt formation on the outer surface of the evaporator tubes occur. Nevertheless, one of the main reasons to replace evaporators by flash distillation mechanisms was the sca le’s low thermal conductivity, which drastically reduced heat transfer efficiency. The first unit was installed in 1960 in Kuw ait (ESCWA-UN, 2001b). The initial design was progressively developed, incorporating the features of the present MSF process. 13,872 desal plants Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 96 a. Multistage Flash (MSF) Distillation Multistage Flash distillation is the most wide ly form to produce water from seawater, especially common wherever the temperature , salt content, biological activity or pollution level of seawater is high, as in the Middle East. This process has been in large- scale commercial use for over 30 years, coupled to power stations. In general, MSF plants are more common because they are simple and robust, although their specific consumption may be higher than other tec hnologies. Other advantage of MSF plants are their unit size, considered of large scale (more than 50,000 m3/d of capacity per unit). The Multistage Flash process (Figure 2.29) is described as follows: seawater pumped through heat exchanger tubes installed in the various evaporator stages, is heated to a certain temperature. Final heating is perfor med by steam (coming from a p ower station) in a brine heater. The hot seawater then goes into flash chambers where the pressure is maintained below the equilibrium pressure corresponding to the temperature at which the brine enters. Part of the brine flashes into vapour and after passing a demister, i t condenses outside the tubes while heating the sea water flowing through the tubes. The multistage flash distillation unit contains cells assembled in seri es, at a different pressure. The water produced in each stage i s coll ected in a trough mounted below the tube bundle which collects the fresh water end product. These widely used units perform recycle brine in order to reduce the qu antity of the make-up seawater needed to produce fresh water. The concentrated seawater is also removed from the last stage by a pump or by gravity. Figure 2.29. Sketch of a typical MSF unit . (source: Uche et al, 2006) b. Multi-Effect Distillation (MED) Contrary to MSF, in Multi-Effect Distillati on evaporation takes place on surfaces, by exchanging the latent heat through the heat transfer surface between condensing vapor on one side and evaporating brine on the other (Figure 2.30). The MED plant also has several stages, ea ch with a heat exchanger tube bundle. Seawater is sprayed onto the tubes and the condensing heating steam inside the tubes evaporates part of the seawater on the outs ide. The steam produced is used as hea ting steam in the next stage, where it condenses in side the tubes. The condensate is the water product. Obviously, the boiling temperatures and pressures in the different evaporators cannot be the same. The first stage is heated by external steam from a heat recovery steam or a back-pressure steam turbine, but in most cases, MED plants are equipped Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 97 with thermal vapor compressors for better e fficiency. The steam produced in the last stage is condensed on the outside of exchanger tubes in a separate condenser, which is cooled by incoming seawater. Part of the heated seawater is then used as feedwater . Product water and concentrated seawater are then pumped out from the last stage of the evaporator. Figure 2.30. Scheme of a MED unit with thermo compre ssor (TVC) (source: Uche et al, 2006) The major advantage of MED with respect to MSF is the ability to produce more water per steam consumed (Per formance Ratio). MED plants could r each a value of 15 while MSF almost 10, and includes lower specific power consumptio n (< 1.5 kWh/m 3 ) than MSF (> 3 kWh/m 3 ). Furthermore, their efficiency does not depend on the steam temperature coming from the turbines as MSF plants, so MED plants are the most promising for thermal distillation technologies for desalination. However, the unit size of MED plants is up to the third with respect to MSF units at present. c. Vapor Compressor Distillation (VC) Vapor compression distillation is similar to multi-effect distillation, but the main difference is that the vapor produced by th e evaporation of the brine inside is not condensed in a separate condenser. In this ca se, that vapor enters in a cen trifugal, single- stage type designed for high-volumetric flows, and this high-energy compressed steam is discharged into the evaporator onto the outs ide of the enhanced surface tubes, where i t condenses and provide its latent heat energy to the boiler seawater inside the tubes. Note that the process is very efficient th ermodyn amically, because most of the shaft work required by the compressor is used to avoid the boiling po int elevation of seawater. In comparison with thermal desalin ation plants, no cooling water is required resulting in smaller intake and pumping systems and lower energy requirements (up to 9 kWh/m 3 of product). Unfortunately, the maxi mum size of VC plants is only about 3,000 m 3 /d but they could grow in capacity and nu mber of effects in order to improve its efficiency and reduce its cost (Figure 2.31). Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 104 seawater RO. New developments will also witness lower use of materials, fewer chemicals and smaller footprints (ESCWA, 2001b). As the success of RO desalination hinges on the proper pre-treatment of the feed water, various membranes could precede the remo val of the monovalent ions by the desalination membrane in order to selecti vely remove suspended solids and decreas e turbidity (microfiltration), organics (u ltrafiltration) and hardness and sulphates (nanofiltration). Various energy recovery devices are now available, such as Pelton wheel turbines, work and pressure exchangers as well as hydraulic turbochargers that can reduce energy requirements by as much as 50 percent. Larger plant size also contributes to the ec onomy of scale that is significant between a plant producing 1,000 m 3 /d and that producing 40,000 m 3 /d, where the capital cost per cubic metre of water can decr ease by a factor of 2.5. However, RO plant sizes larger than 40,000 m 3 /d will not have any further considerable effect on cost reduction. Other trends Owing to the difference in the demand growth factors (11% for water and 4% for power), a decoupling between power and desa lination plants is expected. Where dual- purpose plants are planned, a major trend in technological development is the utilization of more than one process in combination. Such hybrid thermal/membrane combinations offer several advantages including the use of the steam to de-aerate th e feed water and optimization of its temperature for RO, application of the post treatment to the combined product, use of the same s eawater intake, and combining the discharged brine with the recycled brine. Hybrid systems of RO and thermal processes utilize seasonal surpluses of idle power and address the power/water mismatch caused by differences in either daily or seasonal demands. The largest such hybrid plant is in Fujeirah, United Arab Emirates, where MSF desalinates 284,000 m 3 /d and RO desalinates 170,000 m 3 /d. To further address power/water mismatches, using idle power to desalinate would lead to greater water production, hence the need for storage of this excess desalinated water. Therefore, desalination aquifer storage and recovery (DASR) is considered strategic in terms of cost and security. In addition, using filtration processes in conjunction with thermal processes to remove the hardness in the feed water theoretically reduces the scaling potential and allows the thermal plant to be operated at higher tem peratures, hence, greater productivity. Trends that are also worth tracking are the use of renewable energies in desalination, and the growing importance of the environmental impacts of desalination plants. Desalination development potential Desalination has great development potential on a global scale. This is attributed to the fact that out of 71 large cities that do not have local access to new freshwater sources, 42 are coastal. Out of the entire world popu lation, 2 400 million inhabitants (39 percent) live within 100 km of the sea. Current pr oduction of desalinated seawater corresponds only to the demand of 60 million inhabitants. Although desalination has been considered among the non-conventional water re sources, it can no longer be considered as a marginal resource beca use some countries such as Kuwait and Qatar rely 100 Chapter 2. W ater world: resources, uses, quality, technology a nd regulation Exergy cost a ssessment of water r esources: Physi cal Hydronomics 105 percent on desalinated water for domestic and industrial uses (nearly 60 percent in Saudi Arabia). Other than the fact that desalination may be the only option for some countries, there are driving forces behind its development pot ential, making it more favourable than conventional resources. Being independent of climate conditions, rainfall and so on, a primary force is its identification as a secure source of supply. Compared with conventional civil engineering projects, desalination offers advantages in terms of the length of the construction period, which is in the order of 1–3 years, as well as its modular construction allowing the increase in supply to be in line with that of th e demand. In addition, a desalination project is less likely to encounter opposition from local groups or problems associated with cons truction right of way. Furthermore, it is much more attractive to private-sector inve stment than is a dam or a conveyor system. Given these factors, it appears that desalin ation is the only resource for regions with overdrafted groundwater aquifers, albeit in combination with integrated managemen t (primarily that of water demand). 2.8. Summar y of the chapter In this chapter, general aspects about water resources are reviewed. It has been elaborated after a wide bibliography review. Having such an introductory chapter facilitates the understanding of all the following ones, since all the considered items appear disseminated along this work. The distribution of water resources on Ea rth is shown and the main uses of the renewable fresh water are analyzed. Water quali ty characterization is also treated, as well as the main strategies in water management. Key issues brought here to be analyzed are related to the rapid growth of the popula tion, putting more pressure on water supply (demand is increasing), the amount of water is effectively reduced by pollution (supply is decreasing) and the draw of the coming situation. Future tendencies on a global level indicate spectacular growth in the domestic and industrial sectors (especially in underdeveloped countries) and less growth of the water dedicated to irrigation. In developed coun tries there is even a certain reduction of demand because of more efficient u se and also for other reasons not directly related with water management, such as industrial delocalisation, as well as, in the European Union, the pressure of conservation policies such as, for example, those resulting from the Framework Directive. In the last part of the chapter, water de mand and water supply issues are considered. The different water treatment technologies are analyzed, from potabilization to desalination. Inflows and outflows that take part in each process are summarized. Their performance and suitability depending on the situation also appear, since they will be used in the following chapters. Chapter 3. S tatement of the problem Exergy cost assessm ent of water resources: Physical Hydrono mics 107 Chapter 3 Statement of the pr oblem What is the value of water? This chapter tries to approach the question to give an answer to the matter. First of all, it is worth to bring forward here again the already introduced idea in Chapter 2 regarding that water is a natural resource, rather than a molecule or a source of economic utility. Water is, from the very beginning, the primary life-support of a system. In consequence, th e answer will never be universal. In the broadest sense, good or bad is a value. So we are not interested in desires nor wants or, in other words, in values . Instead, the interest is focused on the value of an asset in relation to humankind’s values. Therefore, the valu e of water will always be subjective as subjective are the man values. No general theory of the value of things can be stated accordingly. Also we are looking for number s. We are accustomed to using sentences like the value of that is... a number , or we evaluate projects or men´s work by putting numbers and elaborate rankings. So, the numeri cal value of a thing serves primarily to make comparisons among the different states of that issue or a set of similar things. Besides of that, we are not intending to evaluate the concept water in relation to man, but evaluating some properties of water. In the range of human behaviour, these properties can be physical, chemical, biolog ical, ecological, economic, social or even political and religious ones. Reduction of one typ e into another may be fruitless in many cases. However, two aspects of reality have been quantitatively developed more than others: the scientific and the economic aspects. Science quantifies physical, in a general sense, and biological properties, meanwhile Economics do th e same with costs and prices. Both aspects help us to appr eciate water qualitatively and quantitatively. These two features interact each other. For instance, dirty water s affect health and need depuration that increases its cos t. In spite of it, in the field of water treatment and management, physical aspects and economics are poorly connected. Chapter 3. S tatement of the problem Exergy cost assessm ent of water resources: Physical Hydrono mics 108 To sum up, a new question can be formulated: Is there any systematic relationship between the scientific parameters affecting the quality and quantity of water with the economic ones? Answering this question hi ghly reduces the sc ope of the previous question regarding the value of water , since many aspects of th e value concept have been left aside. We are not interested in social, po litical or ethical values concerni ng the water world. In this sense, many scientific as we ll as economic features of water will not be accounted for. For instance, we exclude from ou r analyses, in the context of this thesis, any biochemical, biological and/or ecological characteristics of waters, apart from the included in the definition of parameters th at we do use, such as the environmental or minimum flow or rivers. At this stage of the presented methodology, the interest is concentrated in physical-chemical properties. The same happens with economic concepts: prices of water a re not the matter, but cost s . Price is what someon e actually pays for a property. It is formed in the interchange. On the contrary, cost refers to production rather than to the exchange. Then, the ideas developed in this thesis could help managers to rationally assess water costs in regular water supply systems. We do not intend to contribute with a theory of everything that substitute broader managing an d political views in the social issue of water. In addition to the development of that message, in this chapter, the concretion to water world is brought through the concept of overcoming scarcity , which is being transformed into the development of means to live with scarcity . Scarcity, water management and the development of social coordination mechanisms for living with it, should be the central focus of water economics. Afterwards, the first Spanish attempt to relate Thermodynamics and water assessment is summarized. The Spanish water acco unts improved the OCDE methodology for water accounting by introducing the quality concept on it, apart from the prescribed quantity. Finally, the currently world-wide most important initiative regarding water accounting is UN’s System of Environmental-Economic Accounting for Water ( SEEAW). It is a conceptual framework for the organization of physical and economic information related to water using concepts, definitions and classifications 3.1. Market v alue, price and cost. The concepts of value, cost and price have appeared in the introduction, although none specific clarifying about them has been done yet. Cost, value, and price are three distinct concepts. However, they are usually confused and used interchangeably, although it is not strictly correct. Market value , unlike cost and price, is always expr essed as a subjective fact or estimation that unavoidably introduces an error. Buyers and sellers add another margin of error because they make decisions based on emotions and personal preferences, not just rational thought. In consequence, it can be said that value is a theoretical concept based on complex human behaviour, i.e., because th ere are a wide variety of beliefs and assumptions about economics and human na ture, there is an ongoing controversy regarding the definition of value . As a result, people have created different value definitions for different uses. The market value has no specific units. Chapter 3. S tatement of the problem Exergy cost assessm ent of water resources: Physical Hydrono mics 109 The price is what someone actually pays for a good. It can give an idea of its value, but it only happens sometimes; what m eans that a buyer may pay more or less for a property than its theoretical market value. Price is expressed in monetary units. Cost may be more precisely defined because it accounts for the different expenses along the production chain, it is the sum of resources to produce something. It comes from actual measurements like the amount of reso urces entering the production process, their prices at the moment of analysis, and other conditions previously defined. The precise assessment of its measurement does not tell us about its objectivity. This is because it depends on the prices of resources enter ing the system which depend on market subjectivities. It may be argued that we always can substitute pri ces of resources by their production costs but, at the chain end, we find the Nature. We are radically ignorant on how many resources were needed to produce natural goods we take for free. Therefore production costs can be precisely evaluated and they are as objective as the prices of consumed resources are. However, cost is calculated from a mixture of physical magnitudes and economic ones. In this sense, cost is closer to th e objectivity of physical facts. Unfortunately, because of the confusion am ong cost, value, and price, parties to a transaction often have difficulty in truly co mmunicating with each other. Th e inclusion of physical laws, more specifically of Thermodynamics, in the analysis could help to manage with those concepts: in particular, the exergy concept. As an example, the exergy content of a bohe mian glass or a stone sculpture, or even gold is zero in practical terms. Many thin gs that society values, thermodynamics does not. The source of value may be or may not be related to its exergy content, even for the case of fuels. Thus, the only thing that Physics can do is to assess the physical cost of objects, i.e., the amount of energy units required to produce a given product, namely embodied energy. The concept of embodied energy comes from the 1970s, when it was a great concern with the first global energy crisis. The problem with energy is the lack of techniques to allocate values of embodied energy when two pro ducts are produced simultaneously. A more precise concept then came: the exergy cost proposed by Valero or the cumulative exergy consumption proposed by Szargut, which ar e in fact similar concepts to embodied energy but using exergy. That cost co uld be defined as the amount of resources needed to obtain a functional product. Cost is therefore an emergent property. It cannot be measured as a physical magnitude of a flow stream as temperature or pressur e; it depends on the system structure and appears as an outcome of the system analysis . In consequence, it needs precise rules for calculating it from physical data. Cost is a property that cannot be found in the product itself. On one hand, resources take a general meaning. On the other hand, cost is associated to the purpose of production. It is associated ne ither with price nor with the resources that could be saved if the production process wer e less efficient or more conventional one. Any resource is measured in some specific units and, in consequence, the introduction of the monetary unit became necessary to unify all the cost. However, the profit concept, Chapter 3. S tatement of the problem Exergy cost assessm ent of water resources: Physical Hydrono mics 110 inherent to the market, makes the cost con cept to disappear in that transformation. Cost is partially erased in the units change. Generally, monetary costs are more objective than price. Prices are formed in the market and are only perfectly presented in ec onomic books. On the con trary, cost of products and services are calculated by a dding (objectively) the resources required to produce them. But resources are, in turn, the products of a previous process tha t consumed new resources, and so on. However, moving backwards to Nature, it is very difficult to know the fai r price (the willingness to pay) of the free resources and services that are continuously taken from Nature. Usually it is deci ded that the cost of natural resources is the imperfect price that they will fetch on the market. In this way, th e chain of the objectivity of cost is broken since this is also formed by price policies th at are not based on Phys ics. In other words, converting monetary cost into energy cost based on the technical input–output coefficients is only justifiable when no alternative and mo re rigorous methods are available. Furthermore, the price-fixing mechanisms ra rely take into account the concrete physical characteristics that make them valuable. But natural capital has at least two physical features which make fresh water, for exampl e, unusual: a particular composition which differentiates it from the surrounding environment, and a distribution which places it in a specific concentration. These intrinsic properties, can be in fact evaluated from a thermodynamic point of view in terms of exergy The calculation of exergoecological costs ca n be proposed for all those products and services, which our society produces from ecosystems and consumes, although they could be sometimes really complicated to estimate due to lack of information. The development of a methodology to objectively asses water cost through the exerg y concept is the main objective of this dissertation. 3.2. Economic assessment of the en vir onmental ser vices In economics, the environment is viewed as a composite asset that pr ovides a variety of services (Tietenberg, 2006). It provides the life-support systems that sustain our existence, so it is a fundamental asset. As it ha ppens in relation to other assets, it is wished to avoid undue d epreciation of the value of this asset so that it can be able to continuously provide aesthetic and life-sustaining services. As Figure 3.1 summarizes, raw materials and energy are provided by the environment. Materials are transformed into consumer prod ucts through the production process, run by energy. After their use, materials and energy are returned to the environment as waste products. The breathed air, the pro tection, the provision of nourishment or the landscape are environmental services that c onsumers also obtain from the environment. The energy received on Earth is mainly from the Sun, either directly or indirectly. The treatment of our Planet and its immediate environment as a closed system has an important implication: the mass of materials flowing into the econo mic system from the environment is return to it as waste in th e same amount (assuming no accumulation) i n the system. In consequence, an excessive waste can d epreciate the asset. If the Chapter 3. S tatement of the problem Exergy cost assessm ent of water resources: Physical Hydrono mics 111 absorptive capacity of nature is exceeded, wastes reduce the services that th e asset provides. THE ENVIRONMENT Energy Air Wa te r Ameniti es Air Poll u tio n Solid Waste Wa st e H ea t W ater Po llution Fi rm s (P r o du ction ) Househol ds (Con sumpt ion) Inputs Outp uts THE ECONOMY Raw Materials THE ENVIRONMENT Energy Air Wa te r Ameniti es Air Poll u tio n Solid Waste Wa st e H ea t W ater Po llution Firms (Pro duction) Househol ds (Con sumpt ion) Inputs Outp uts THE ECONOMY Raw Materials Figure 3.1. The economic system an d the environment (Source: adapted from Tietenberg, 2006) The Second Law of Thermodynamics states the irreversibility of any consumption of energy, that is, the entropy increases because some en ergy is always lost during the conversion, and the rest, once used, is no long er available for further work. The Second Law also implies that in the absence of new energy inputs, any closed system must eventually use up its energy. Since energy is necessary for life, life ceases when energy ceases. Our planet is not even approximately a closed system with respect to energy because of the energy gained from the sun. The Entropy Law suggest, however, that this flow of solar energy established an upper limit on the flow of energy that can be sustained. In the future, if the stored energy in fossil and nuclear fuels is depleted, the amount of energy available for useful work will be only determined by this flow and by the amount that can be stored in dams or biomass. Assum ing this situation the growth process, over the long run, will be limited by the availability of solar energy and our ability to put it to work. Whatever the chosen approach to asses na tural resources, it must be first wel l understood the relationship between the economic system, natural resources, and the environment. That is why, in this chapter, a brief historical review about the nature environment and economics interaction is carried out. Speci al attention is devoted to Georgescu-Roegen, Daly or Naredo, whose id eas are considered as milestones for the framework of this dissertation: the Ecointegrator approach. 3.2.1. The accounting systems: from Mercantilism to the Physiocrats and th e Ricardian Earth. The genesis of the theoretical background fo r the current national accounting Systems, guiding the macroeconomist’ thought, dates from 18 th Century (Naredo, 1987). Before that time, the Mercantilism was the dominant school of thought throughout the early modern period (from the 16 th to the 18 th Century). Chapter 3. S tatement of the problem Exergy cost assessm ent of water resources: Physical Hydrono mics 112 Mercantilism’s background is based on the st atement that the prosperity of a nation is dependent upon its supply of capital. In this economic theory, it is assumed that th e global volume of international trade is unchangeable and that the economic assets or capital are represented by gold, silver, and trad e value (defined as bullion). It is held by the state and can increase through a positive balance of trade with other n ations. The economic system is seen as a zero-sum game , in which any gain by one party required a loss by another. Thus, any system of policies t hat benefited one group would by definition harm the other, and there wa s no possibility of economics being used to maximize the common good (Landreth and Col ander, 2002). Mercantilists' interest lies in rationalize particular practices rather than in establishing the best poli cies (Landes, 1997). They defend a protectionist role of the government in relation to the economy of the country, by encouraging exports and di scouraging imports, by using tariffs and subsidies. From there Montesquiev considered the Economy as the science of richness acquisition . Having this in mind, it can be understood , as Naredo mentions (Naredo and Valero, 1999), that the Spaniards in America, when offered mirrors and glass pieces to the aborigine in exchange for gold and gemstones, were perfectly conscious about committing an unfair trade. Nevertheless, natural resources are nowadays extracted from poor countries in exchange for less valuab le assets such as informatics or financial products, and the conscience about the swindle does not exist a ny more. Thus, the strengthening of Economics was not any more based on the acquisition, but on the richness production. It was n eeded to wait until the works of the today called Physiocrats, to establish the notion of production as centre of the modern version of the economic system. The group of economics designed as Physiocrats thought that the wealth of nations was exclusively derived from the development of land and agriculture, and the value that is produced. Physiocrats’ theor ies were initially developed in France and their popularity increased by the second half of the 18 th Century, becoming a ver y well structured theory of Economics. Two impor tant leaders of this current were Anne- Robert-Jacques Turgot and François Quesnay. Quesnay publi shed the famous Tableau économique in 1758, trying to orientate the techni ques to obtain higher efficiency rates in all the productive activities. Physiocracy immediately preceded the first modern school, classical economics, which began with the publication of Adam Smith's The Wealth of Nations , in 1776 (Nell, 2009). The Physiocrats’ emphasis on productive work as the only source of nation al wealth is in contrast to earlier schools which often focused on the accumulation of bullion or the balance of trade. However, they only considered agricultural labour as valuable, what is seen as an important weakness from the point of view of modern tendencies. The modern economists understand the producti on of goods and services as productive activities to be added to the national inco me. However, for the Physiocrats, precursors of the anti-mercantilist movement, those were th e investment of the agricultural surplus. Physiocrats developed their theory in a completely agricultural French economy (agriculture was 80% of the country’s wealt h). Quesnay’s ideas against industry and international trade are ba sed on the belief that industry production does not mean any gain in wealth. If labour from agriculture is invested into industry, the overall wealth would decrease. As a consequence, population should decrease if the avail able land to produce food disappears in favour of industry. In addition to that, the trade proposed Chapter 3. S tatement of the problem Exergy cost assessm ent of water resources: Physical Hydrono mics 113 by Mercantilists assumes that there exits mo re of a resource than it needs for internal consumption and therefore that resource can be tradeable. As a summary, it can be said that Physiocrats linked all the generation capacities to the Mother Earth . Once established the economic system idea with its production and consumption carousel, and accepted the target of its ex pansion and continuous growth, a movement of this ideal system from the physical contex t (where it was initially formulated) to th e universe of monetary values, was operated. Such a displacement happens at the same time that the developments of the Nature sciences invalidated the archaic vi sion of the world and the eagerness of controllin g the underlying physical growth. As a matter of fact, when the mineralo gy, supported by the modern Chemistry knowledges, refuted the ancient believes about the growth of the minerals inside the Earth, and when Geodesy obtained accepted measurements of the Earth meridian, the ideas of production and growth of the aggregates of the economic system distanced from the physical world until being completely confined in the self-sufficient value universe. Those authors finished the cut of the nexus th at still joined the idea of economic system to the surrounding physical world trough the concept of ricardian eart h : the Earth, with all its resources, as well as work, are replacea ble by capital. Ricardo's most famous work is his Principles of Political Economy and Taxation (1817), where he states the l abour theory of value: the relative price of two goods is determined by the ratio of the quantities of labour required in their production. From it, it is derived that the effects on income are always beneficial because foreign trade does not affect value a nd it is always benefits (comparative advantage). Net product is selling off with profit. Ricardo was an opponent of protectionism for national economies, as also Adam Smith was . The central aggregate of the current nationa l accounting systems is an added-value balance resulted from subtracting the sale value from the import spent in their obtaining. The physical processes are left out. It is relevant to add at this point that the developed countries, cradle of the Industrial Revolution, are used to derivate an important pa rt of their negative externalities far from their own territories, charging them on the rest of the Planet. This issue is related to the existing deep asymmetry betwe en the monetary valuation and the physical cost along the whole general economic process. It leads to th e physical inequality related to the costs, that underlies from the monetary equality of the interchanges in the own world trade. In this context, appeared new concepts such as the ecological rucksack, which estimates the ecological deterioration dragging by the pr oducts along their production process; or the ecological footprint, a measure of hu man demand on th e Earth's ecosystems that represents the amount of biolog ically productive land and sea area needed to regenerate the resources a human population consumes and to absorb and render harmless the corresponding waste (Naredo and Valero, 1998). 3.2.2. Georgescu-Roegen: the change of the paradigm. Although the idea of getting closer the environment and the economy had been largely treated, the Nicolas Georgescu-Roegen’s contri bution deserves a special attention. He is considered as one of the most remarkable and profound thinkers in modern economics. Chapter 3. S tatement of the problem Exergy cost assessm ent of water resources: Physical Hydrono mics 120 Because of its interest and the provided co mplementary vision, this emergy approach will be further developed in the Chapter 7 of this dissertation. Second Thermodynamics Law as working tool A further step in the valuation of Environment within Economics is including the quality and degradation aspects in the analysis. From a physical perspective, it means to include the Second Thermodynamics Law (entr opy law). Tha t is, taking exergy as the working tool. From the Industrial Revolution until today, the development and continuous efficiency improvements of the energetic and industrial sectors have been tightly jo ined to the Thermodynamics principles. None of the advan ces can be understood without its proper thermodynamics context. In addition to its traditional industrial traj ectory, the Exergy analysis has been performed in the field of Industrial Ecology to use en ergy more efficiently (Wall, 1986). In recent decades, utilization of exergy has spread outs ide of physics and engineering t o the fields of Industrial Ecology, Ecological Economics, Systems Ecology, and Energetics (e.g., Jørgensen et al., 2000; Rosen and Dincer, 2001; Gong and Wall, 2001; Wall, 2002; Szargut, 2003, 2004; Chen, 2006). The resource accounting in terms of exergy has been carried out based on nation or industrial sector scales (Chen, 2007). Di ncer (2002) paid much attention to the relationship between energy utilization and the environmental impacts, and highlighted the implication of the exergy analysis to the sustainable development. Hellstörm (1997, 2003) estimated and compar ed the exergy consumption of physical resources in some wastewater treatment plants and sewerage systems. Fi nnveden and Östlund (1997) and Ayres et al. (2002) have developed an Exergy Based Life Cycle Analysis, introducing the concept of exergy into the methodology of environmental lif e cycle assessment and using it as a uniform indicator of total environmental impact. In a framework for systems evaluation based on exergy circuit language, ecological value for a waste stream is defined negative and equal in magnitude to corresponding embodied exergy in terms of the total exergy consumed in human helped treatmen t or natural degradation of the waste water stream (Chen, 2006). Chen (2007) developed for a unified objective assessment of water quality, the chemical exergy based evaluation method. While a quantity termed specific standa rd chemical exergy based on the global reference substances might be adopted, an indicator as specific relative chemical exergy with refe rence to a spectrum of substances associated with the specified water quality standard is proposed for water quality evaluation. So it has more practical implications, resulting in unified objective quantifiers for the carrying capacity and carrying deficit of water resources. With data coll ected in the GEMS/WATER project, water qualities of 72 rivers and 24 lakes over the world wer e evaluated as a detailed case study to illustra te the adaptability of the chemical exergy based indicators for water quality evaluation. Chapter 3. S tatement of the problem Exergy cost assessm ent of water resources: Physical Hydrono mics 121 3.3.3. Comparative: Environmental Eco nom ics vs. Ecological Economics. Ecological Economics seeks to recognize what traditional economics often ignores; that the Economy is embedded in wider social and biophysical systems (Dodds, 1997). Ecological economics is distinguished from Environmental Economics by its connection to disciplines within the natural sciences and its focus on how to operate an economy within the ecological constrai nts of Earth's natural resources. Ecology deals with the energy and matter transactions of life and the Earth, and th e human economy is by definition contained within this system. Economic theory, as encapsulated in general equilibrium models , assumes both an infinite resource base and also infinite waste sinks with no feedbacks. This allows neoclassical economics to clai m theoretically that infinite economic growth is both possible and desirable, what disagrees with much of what th e natural sciences have learned about the world and, according to Ecological Economics, completely ignores the contributions of Nature to the creation of wealth. As an example, the planetary en dowment of scarce matter and energy, along with the complex and bi ologically diverse ecosystems that provide goods and ecosystem services directly to human communities: mi cro- and macro-climate regulation, water recycling, water purification, storm water regulation, waste absorption, food and medicine production, pollination, protection from solar and cosmic radiation, the view of a starry night sky, etc. Resource and neoclassical economics focus primarily on the efficient allocation of resources, and less on two other fund amental economic problems which are central to Ecological Economics: distribution (equity) and the scale of the economy r elative to the ecosystems upon which it is reliant (Daly and Farley, 2004). Ecological economics uses tools from math ematical economics, but may apply them more closely to the natural world, i.e. , the physical laws. Whereas mainstream economists tend to be technological optimists, ecological economists are inclined to be technological pessimists. They reason that the natural world has a limited carrying capacity and that its resources may run out. Since destruction of important environmental resources could be practically irreversible and catastrophic, ecological economists are inclined to justify cauti onary measures based on the precautionary principle (Costanza, 1989). These two groups of specialists sometimes have conflicting views which can often be traced to the different philosophical underpi nnings of the two fields. Some ecologists subscribe to deontological ethical systems; other economists subscribe to teleological ethical systems (Mazilu and Ciobanu, 2009). Et hical system can not be demonstrated to be right or wrong, but they may someti mes have different implications for environmental policy. Environmental economics is viewed as relatively more pragmatic in a price system; ecological economics as relatively more idealistic as it supposedly does not use money to arbiter decision making as much. Chapter 3. S tatement of the problem Exergy cost assessm ent of water resources: Physical Hydrono mics 122 3.4. W ater as an economic good Starting from the Agenda 21 and the Dub lin Principles, which put the co ncept of water as an economic good on the global agenda, Peter Rogers tried to clarify the substantial confusion about its meaning (Rogers et al , 1998). He addressed the lack of understanding by formulating the concept of water as an econo mic good and explaining, in practical terms, the economic tools that can be used to ef fect the environmentally, socially, and economically efficient use of water. He defends the potential role of economic tools in providing socially acceptable public decisions. As a summary of that work, some useful idea s are reproduced here in order to correctly locate the WFD’s requirement regarding water cos ts. In assessing the economic value of water and th e costs associated with its provision, two main aspects have to be observed: the cost involved in the provision of water and th e value of the use of water. Regardless of the method of estimation, the ideal for the sustainable use of water requires that the values and the costs should balance each other; full cost must equal the sustainable value in use (see Figure 3.2). Figure 3.2. Gen eral principles for co st of water acco rdin g to Roger’s work (Rogers et al, 1998) Three important concepts can be identifi ed: the Full Supply Cost, the Full Economic Cost; and the Full Cost. The Full Supply Cost includes the costs associated with the water supply to a consumer without consideration neither of the exter nalities imposed upon others nor of the alternate uses of the water. Full Supply Costs are composed of two separate items : Operation and Maintenance (O&M) Cost, and Capital Charges, both of which should be evaluated at the full economic cost of inputs. The Full Economic Cost of water is the sum of the Full Supply Cos t, the Opportunity Cost associated with the alternate use of the same water resource, and the economic externalities imposed upon others due to the consumption of water by a specific actor. Chapter 3. S tatement of the problem Exergy cost assessm ent of water resources: Physical Hydrono mics 123 The Full Cost of consumption of water is the Full Economic Cost, given above, plus the Environmental Externalities. These costs have to be determined based upon the damages caused, where such data are available, or as additional costs of treatment to return the water to its original quality. According to Rogers et al. (1998), for economic equilibrium, the value of water, which is estimated from the value in use, should just equal the full cost of water. The value in u se is typically expected to be higher than the estimated full cost. This is often because of difficulties in estimating the environmental externalities in the full cost calculations. 3.5. Costs definition in the WFD . The European legislation (WFD) explicitly says in its Article 9 that Member Stat es shall take account of the principle of recovery of the costs of water services, including envi ronmental and resource costs, having regard to the economic analys is… and in accordance i n pa rticular with the polluter pays principle. In consequence, water pricing policies shou ld be readjusted by 2010 following the guidelines of the Full Cost Recovery Princi ple (FCR) stated in the Directi ve. That text does not explicitly use the term full or integra l cost recovery (in Article 9, as reproduced in previous paragraph, it just mention that the cost recovery pr inciple concerning water has to be taken into account). This f act leads to consider the possibility of modulating the principle and of establishing exceptions , as long as they are suitably justified. Regarding users, at least industry, households and agriculture will be taken into account by using the Polluter Pays Principle. However, it does clearly state that, when it talks about the cost concept, it is not just referring to costs in the conventional economic sense but that it considers even the environmental costs and those concerning the resource. The FCR concept contains diverse terms, which according to the WATECO g roup guide (ECO2, 2004) are: - financial costs (or services costs) include the cost of providing and administering water services, such as supply, sanitation, tran sport and storage, which at present are reflected to users in minor or major quantity. They include all operation and maintenance costs, and capital costs (principal and interest payment), and return on equity where appropriate, i.e., the costs of depreciation of capital, the costs of financing, the costs of maintenance an d runnin g, the administrative costs and other direct costs that could be included. - environmental cost regarding the alteration of the ph ysical and biol ogical aspects of water bodies due to human activities. It re presents the cost of damage that water uses impose on the environment and ecosystems and tho se who use the environment (e.g. a reduction in the ecological quality of aquatic ecosystems or the salinisation and degr adation of productive soils). In consequence, the environmental cost also includes “econom ic externalities” such as the loss of employment in the services sector in ru ral areas due to the impacts of a social nature due to the degradation of the water resources. - resource cost as the cost of foregone opportuni ties which other uses suffer due to the depletion of the resource beyond its natural rate of recharge or recovery, Chapter 3. S tatement of the problem Exergy cost assessm ent of water resources: Physical Hydrono mics 124 derived from an inefficient or alternative use (for example, linked to the over- abstraction of underground waters). The first term could be easily calculated from classical economic accountancy. However the second and third terms are obvio usly more di fficult to evaluate, at least with current analysis tools in existing water management policies. 3.5.1. The Ecointegrator approach As measurements are gradually introduced to r estore water bodies, they should be considered as financial costs following the FCR concept, and therefore double accounting could appear if this circumstance is not taken into account. This idea has been already highlighted by many authors. Naredo (2007) presented some interesting graphics showing this idea; they have been adapted and reproduced in the Fi gure 3.3. Figure 3.3. Costs in the standard economic approach, adapted to the WFD requ irements (Source: Naredo, 2007) According to Naredo, the underlying hypot hesis comes from traditional Economics and indicates that the mentioned costs are one- dimension (only expressed in monetary units), they do not overlap (forming disjoint sets) and they are additive (they have to be added to obtain the total cost to be assigned to the users). After a detailed analysis of the restrictions in cluded in the WFD’s costs definitions by a traditional economics interpretation (see Naredo , 2007), this author describes a ne w methodological proposal aimed to open th e closed (and generally one-dimensional) reasoning outlines. In this way, the a pproa ch could be open to open, multidimensional and transdisciplinary treatments, more ade quate for the management of the current industrial society. Naredo’s proposal does not try to eliminate or marginalize the monetary and hydraulic traditional approaches, but relocate them in the wider frame of the new approaches. As an example, the study and good information of the environmental costs of water body is not called to exclude the studies devoted to know the willingness to pay for its environmental quality. It just derivates to further exercises of informed social participation serving to reach a consensus a bout quality standards with full knowledge of the reason why cost are originated and their payment repercussions. W ater Servic es cost (WFD) (monetary co st derived of water services utilities) Resource cost ( WFD) (Opportunity cost) Environment a l cost (WFD) (environmental externalities) T T O O T T A A L L C C O O S S T T Environment a l cost (to become monetary) d Potential value s (to become monetary) Comercial values (to become monetary) Chapter 3. S tatement of the problem Exergy cost assessm ent of water resources: Physical Hydrono mics 125 The proposed calculation methodolog y for the water costs affirms its pluridimensionality, what does not denies, but reinforce, the monetary approaches offering new support points. It also consid ers that the service, environmental and resource costs are not disjoint sets (and th erefore neither additive), but they overlap: water management must precisely be able to play with those intersections and overlaps in order to design reasonable economic tools. These ideas are summarized in the called Ecointegrator Approach , whose main interest is in orienting the water costs to get that the co st of the water service fairly reflects th e environmental and recource cost, attending to the good water management principles and passing from the case A to the case B represented in Figure 3.4 and Figu re 3.5. Case A: The service costs (monetary) hardly account for the environmental and resources cost. Case B: The service costs (monetary) reflect an important part of the environmental and resource costs. E E f f f f e e c c t t i i v v e e ( ( m m o o n n e e t t a a r r y y ) ) c c o o s s t t o o f f o o b b t t a a i i n n i i n n g g t t h h e e r r e e s s o o u u r r c c e e E E f f f f e e c c t t i i v v e e e e n n v v i i r r o o n n m m e e n n t t a a l l ( ( m m o o n n e e t t a a r r y y ) ) c c o o s s t t ( ( o o f f r r e e s s t t o o r r i i n n g g t t h h e e e e n n v v i i r r o o n n m m e e n n t t a a l l d d e e t t e e r r i i o o r r a a t t i i o o n n d d u u e e t t o o w w a a t t e e r r u u s s e e s s ) ) . . Water servi ce (monetary ) cost E E f f f f e e c c t t i i v v e e ( ( m m o o n n e e t t a a r r y y ) ) c c o o s s t t o o f f o o b b t t a a i i n n i i n n g g t t h h e e r r e e s s o o u u r r c c e e E E f f f f e e c c t t i i v v e e e e n n v v i i r r o o n n m m e e n n t t a a l l ( ( m m o o n n e e t t a a r r y y ) ) c c o o s s t t Water service (monetary) cost Figure 3.4. Small overlap o f the different water costs (Source: Naredo , 2007) Figure 3.5. O verlap of the differ ent water costs, Ecointegra tor approach (Source: Naredo, 2007) The implicit hypothesis is: 1º) The costs are pl uri-dimensional (they can be quantified in monetary and physical units), 2º) Its moneta ry version chang es with the institutional Framework, which provokes overlapping of th e environmental and resource (obtaining) costs with the service cost, and 3º) The three costs are not additive: the service costs has to account for the environmental and resource costs. A water management system that observe s the WFD Principles about the costs recuperation and the degrader pays principle, the service cost of water should account for the environmental costs as well as for th e resource cost. At the same time, the water tariffs regime should be adapted to the re sulting costs panorama, except in specially justified exceptions. Chapter 3. S tatement of the problem Exergy cost assessm ent of water resources: Physical Hydrono mics 126 3.6. W ater , scarcity and their mana gement. Like many natural products, water’s worth has increased as its usage has risen. A huge amount of water-related issues are growing in terest for the last years. Its availability has also been affected by the notion that has come to be called the environmental Kuznets curve – rising income levels bring even greater increases in the demand for a better environment and this often incorporates the non-use of rivers, forests and land. Kuznets curve is the graphical representati on of Simon Kuznets's theory that economic inequality increases over time while a country is developing, then after a critical average income is attained, begins to decrease. Despite the best efforts of scientist and engi neers, scarcity prevails today. Demands for water have continued to increase with expa nsions of irrigated agriculture, resource processing, industrial application and dome stic use. There has also been a growing recognition of the inverse relationship between the health of riverine ecologies and the extent of water extractions. This has pr omoted the emergence of demands for environmental flows in rivers. At the same time, the total amount of water available remains constant (if somewhat stochastic) and the possibilities for relocating water have been reduced through increased competition for the environmental resources required for the construction of dams. Furthermore, water supply is, in places, becoming increasingly compromised in terms of its sui tability for different purposes because of quality deteriorations. Hence the saga of overcoming scarcity is being transformed into the development of means to live with scarcity . This means attempting to make the most of the water that is available, primarily through the establishment of institutions that provide the incentives fo r society to derive maximum social well-being through its access to the water resource. Scarcity, and the development of social coor dination mechanisms for living with it, is the central focus of water economics. Water management, understood as the practi ces of planning, deve loping, distribution and optimum utilizing of water resources unde r defined water polices and regulations, is the instrument to deal with the giving situation. In general terms, the concept of water as a resource or as a natural heritage element subject to accounting derives from the at tempt to find the interaction b etween the discipline that studies the behaviour of water as a nat ural entity (Hydrology) and that which tries to regulate its management (Water Economy or Hydroeconomy). The search of this interaction has given rise to different accounting procedures in different countries, until finally arriving at the methodology proposed by the Organisation for Economic Co-operation and Development (OECD). It only referred to Water Quantity Accounts. The currently world-wide most important init iative regarding water accounting is UN’s System of Environmental-Economic Accoun ting for Water (SEEAW). The SEEAW is a conceptual framework for the organization of physical and economic information related to water using concepts, definitions and classifications consistent to those of the System of National Accounts (UN-SNA, 1993). Chapter 3. S tatement of the problem Exergy cost assessm ent of water resources: Physical Hydrono mics 127 In Spain, the first attempt to relate Th ermodynamics and water assessment i s known as the Spanish Water Accounts (Naredo, 19 97). They were primarily established to assemble water-related information (both physical and monetary) within the consistent and useful framework needed to regulate wa ter management with economic criteria. Besides being of critical importance to all governments endowed with legal responsibility and authority over the economic management of water resources, this objective concurred with the demands of the 1985 Spanish Water Act (WA) which recognised, for the first time ever, the unit ary character of the hydrological cycle (thus repealing the deep-rooted yet artificial di vision made between surface and ground waters) and laid down the unitary character of the management of the “public ownership of the continental waters”. Title III of this Act entrusted the entity in ch arge of Hydrological Planning with the task of drawing up a water policy based on this unitary and comprehensive view of the hydrological cycle and on rational and econom ic criteria for the management of the country’s water resources, considered to be “scarce and essential”, among other tenets. In light of this, it becomes apparent that the Water Accounts were expected to furnish a complete and orderly system of information on which to base the design and application of hydrological planning policies. In addition to the above-mentioned objective, the WA was also destined to serve other purposes. Since its establishment required that all the available data were employed to construct a complete system of information relating the water situation from the view point of both the resource (Hydrology) and th e economic agents or transactors involved in its utilisation (Economy), they made it po ssible to detect gaps and inconsistencies in the statistics used and gave rise to new a ppraisals of water eco nomy problems that had gone unnoticed with the traditional parcelling approaches. Finally, the development of Spanish WA also met the need to place the wa ter management concerns peculiar to Spain within the context of the more ample Natural Resources Accounts established by other European countries (Naredo, 1997). During the last decades, Spain has been very acti ve in this field. The development of the Spanish Water Accounts resulted, in part, from the OECD request that the Spanish government apply the pilot water account methodology adopted by this organisation (a simplified version of the methodology app lied in France in 1986) in Spain, where dryness and aridity are prevailing characteris tics. It constituted a milestone in water quality accounting because, at that ti me SEEAW did not exist (the current document was the SEEA, which accounted only for quantity). The results of applying an adapted version of the mentioned accounting exercise in Spain concurrently enriched and synthesised the OECD (and even th e original French) methodology. Thus, they met the twofold purpose of contributing relevant methodological observations and of placing data (both physical and monetary) within the global framework needed to take economic water management decisions in Spain, where water scarcity and ill-quality problems ar e more pressing that in the European countries lying north of the Pyrenees (Naredo, 1997). These two works, which are the background for the methodology developed in this dissertation, are going to be explained next. Chapter 3. S tatement of the problem Exergy cost assessm ent of water resources: Physical Hydrono mics 128 3.6.1. System of Environmental-Economic Accounting (SEEA) Environmental–economic accounting is a response to the need for integrating environmental policies into the overall sy stem of decision making. The European Environment Agency has started the implementation of a programme of land use and ecosystem accounts, following the System of Environmental an d Economic Accounts (SEEA) guidelines of the United Nations (U N-SEEA, 2003). The purpose is to integrate information across the various ecosystem components and to support further assessments and modelling of these components and their interactions with economic and social developments. The construction of land and ecosystem accounts is now feasible due to continuou s improvements in monitoring, collecting and processing data and progress with the development of statistical methods that fac ilitate data assimilation and integ ration. The accounts are based on explicit spatial patterns provided by comprehensive land cover accounts that can be scaled up and down u sing a 1 km 2 grid to any type of administrative region or ecosystem zone (e.g. , river basin catchments, coastal zones or bio-geographic areas). Land cover accounts hav e been produced for 24 countries in Europe and first results published in th e European Environment State and Outlook 2005 report of the EEA (EEA, 2006). It aims first at clarifying and quantifying the use of the environment in the broader sense, marketed resources as well as services not presently internalized by the economy. The purpose is to assess public and private benefits and costs and to optimize the use of environmental resources taking into account a longer time frame and future options. Direct benefits and costs have to be a ssessed together with indirect – sometimes “hidden” – ones, in order to supply priva te and public decision makers with adequate information about the trade-offs they face. This means addressing in clear terms the possible impacts of environmental degrad ation on the economy, on population as wel l as on the ecosystems themselves. The ecosystem concept is certainly not n ew in ecological economics, and has existed within environmental accounting since the ve ry beginning of the formal developments that resulted in the SEEA 2003. Ecosystem accounts are in no way a substitute for ecological or economic modelling. Instead, they aim to organise and present data in a way that facilitates their assimilation an d use by researchers and decision makers. This idea has been developed in the water m anagement field through the Integrated Water Resource Management in agreement with the WFD. Main characteristic of this propose actuation way are collected in the fo llowing, with special attention to its accounting tool: the SEEAW. 3.6.1.1. Integrated Water Resource Management (IWRM) Integrated water resources management (IWRM) is based on the perception of water as an integral part of the ecosystem, a natural resource and a social and econ omic good, whose quantity and quality determine the nature of its utilization. To this end, water resources have to be protected, taking in to account the functioning of aquatic Chapter 3. S tatement of the problem Exergy cost assessm ent of water resources: Physical Hydrono mics 129 ecosystems and the perennially of the resource, in order to satisfy and reconcile needs for water in human activities. In developing and using water resources, priority has to b e given to the satisfaction of basic needs an d the safeguarding of ecosystems. Beyond these requirements, however, water users s hould be charged appropriately (UN-Agenda 21, 1992). IWRM calls for a sustainable management of water resources to ensure that there is enough water for future generations and th at water meets high quality standards. An IWRM approach promotes the coordinated development and managemen t of water, land and related resources in order to maximize the resultant economic and social welfare in an equitable manner without compromising the sustainability of vital ecosystems. This includes more coordinated development of (a) land and water; (b) surface and groundwater; (c) the river basin and its coastal and marine environment; and (d) upstream and downstream interests (Global Water Partnership, 2004). For policy-making and planning, taking an IWRM approach requires that (a) policies and priorities take water resources implications into account, including the two-way relationship between macro-economic policie s and water development, management and use; (b) there is cross-sectoral integrati on in policy development; (c) stakeholders are given a voice in water planning and mana gement; (d) water-related decisions made at local and river-basin levels are in-line wi th, or at l east do not conflict with, the achievement of broad national objectives; and (e) water planning and strategies are integrated into broader social, economic and environmental goals (GWP, 2004). The SEEAW is a useful tool in support of IWRM by providing the information system to feed knowledge into the decision-making pr ocess. Because of its features, outlined in the previous section, the SEEAW can assist policy makers in taking informed decisions on allocating water resources efficiently, im proving water efficiency, understanding the impacts of water management on all users, getting the most value for money from investment in infrastructure, Linking water availability and use, providing a standardized information system which harmonizes information from different sources, is accep ted by the stakeholders and is used for the deriva tion of indicators and getting stakeholders involved in decision-making. System of Environmental-Economic Accounting for Water (SEEAW) The System of Environmental-Economic A ccounting for Water, common ly referred to as SEEAW (UN-SEEAW, 2007), has been prepared by the United Nations Statistics Division in collaboration with the London Group on Environmental Accounting, in particular, with its Sub-Group on Water A ccounting along the last three years. Because water is critical and intimately lin ked with socio-economic development, it is necessary for countries to move away from secto ral development and management of water resources and to adopt an integrated overall approach to water management (UN- WWAP, 2006). The SEEAW is a conceptual framework for the organization of physical and economic information related to water using concepts, definitions and classifications consistent to those of the System of National Acco unts 1993 (UN-SNA, 1993). The SEEAW Chapter 5. Exergy assess ment in a wate r course: Physical Hydronomics Exergy cost assessm ent of water r esources: Physical Hydrono mics 232 Data treatment is a hard task that h as to be carefully planned. In this work, input data have been monthly organised in excel sheets. The initial and final states have to be clearly defi ned, both in quantity and quality, in order to correctly operate. The quantity component is explained in detail in Table 5.22. In general, the flow of the initial state is wr itten directly and the flow of the final state is expressed as that initial flow plus addi tional flow that separates both states (Q initial + Δ Q where Δ Q =Q final -Q init ial ). This technique allows a better structure and results’ organization. The quality component is obtained from the simulations (Qual 2k) or from the legal references. River state Q init ial Q fina l b initial b final SC Q ES Q ES +(Q PS -Q ES ) b ES b PS FS OS EC (OS=GE E) Q FS Q GEE =Q FS + Δ Q w here Δ Q=0 if Q FS >Q MF Δ Q=Q MF -Q FS if Q FS <Q MF b FS b GEE EC (OS=HS) Q FS Q HS =Q GEE + Δ Q where Δ Q=Q NF -Q GEE b FS b HS RRC Q GEE or Q HS Q NF b OS b NF Table 5.22. Correspondence of real and ob jective state for each cost For the SC calculation, in general, Q real =Q exp because only a quality change is assumed and there is not a physical consumption in th e water treatm ent plants. If it were exist, Q PS <Q ES and, in consequence a negative value would appear ( Δ Q<0). Quality parameters are obtained from the river simulation program. Upon the EC calculation, objective flows an d qu alities are obtained from GEE and HS definitions. Regarding Δ Q, Q 2015 >Q man in general because Q man is defined as a minimum required flow. Quality parameters for 2015 are simulated by the Qual2k software and the quantity for the maintenance flow is legally determined. The RRC is a fixed cost. Q NF is obtained from flow restoration to natural regime studies (Sacramento. Nolte or Sato Method), and th e quality of this natural flow is determined by the competent organism, depending on the typ e or river, and observing always the stablished objectives by 2015. The presence of Δ Q in calculations allows considering separately th e quantity and quality components. if needed. This feature w ill be especially important when, in an ulterior step, pollution abatement measurements will be proposed. 5.10. Sign anal ysis for w ater costs The expected signs for the calculated water co sts are analyzed in this section. For each cost, its potential and chemical component is considered. Their corresponding quantity and quality components are considered separately, keeping in mind that diverse measurement plans will be applied. The follo wing expression, used for th e analysis, is Chapter 5. Exergy assess ment in a wate r course: Physical Hydronomics Exergy cost assessm ent of water r esources: Physical Hydrono mics 233 followed from Eq. 5.3. The subindex r and o state for the initial (real) and final (objective) states in each case. Eq. 5.18. r o r r o r l t )·db m - (m ) db - (db m B B B + = Δ + Δ = Δ In the cases where the resulted sign is clear, the expected result (positive, negative, null) has been marked with a square in the diagram. Where the final sign cannot be immediately predicted, all the possibilities are shown without any special mark. Options in red are impossible. 5.10.1. Sign analysis for the Service Cost The flow has been assumed equal for the exploitation and present states of the river, so the quantity component of the se rvice exergy cost does exist, neither for the potential nor for the chemical component. The quality component coming from the potential component of the service cost is also zero because the altitude is maintained. Howev er, the IM is usually lightly lower in the present than in the exploitation state and, in consequence the SC l,IM is positive (although not high in magnitude). The OM in the exploi tation state (ES) is much higher than in the present state because, as indicated in the ES definition, the river suffers from the absence of WWTPs. Then, the sign for the SC l,OM is negative in most cases. Figure 5.15. Signs analysis f or the Service Cost Chapter 5. Exergy assess ment in a wate r course: Physical Hydronomics Exergy cost assessm ent of water r esources: Physical Hydrono mics 234 5.10.2. Sign analysis for the Environmental Cost The flow in the OS is usually higher than the flow in the FS (Q OS >Q FS ). Consequentl y, the quantity components of the EC are expe cted to result positive. However, it may happen that the river, in its current state (FS) receives many artificial tributaries (from other watersheds, from aquifers…), having in some reaches of its courses a flow higher than its natural flow regime and also higher than the OS: Q OS <Q FS and the quantity component of the EC will result negative. The quality of the potential component, EC l,pot , is zero because of the constant altitude in each reach. However, the most comm on result of the EC for the other quality components can not be directly defined. It w ill depend on the v alues of the IM and the OM in the future state of the river and in th e objective state. If the river is not polluted and the values derived from its chemical are lower than th e marked objectives, no restoration measurements will be needed. Then, the EC l is zero (in fact, negative, but it is understood as zero). If the situation is the contrary, the chemical quality of the future state is lower than the demanded by the legislation (OS), the EC l will be positive and some kind of measurements will need to be implemented. Figure 5.16. Signs analysis f or the Environmental Cos t Chapter 5. Exergy assess ment in a wate r course: Physical Hydronomics Exergy cost assessm ent of water r esources: Physical Hydrono mics 235 5.10.3. Sign analysis for the Remaining Resource Cos t The RRC represents the highest exergy gap in most cases. It accounts for the exergy distance between the objective (OS) and the na tural state (NS) of the river and, in the first instance, it is expected that the flow and the quality were both higher in the NS than in the OS. Accordingly, their quantity components are usually positive and their quality components will follow the regular tendency: RRC l,p ot =0, RRC l,IM >0 and RRC l,OM <0. In some few and particular situations, it ma y happen that the flow in the NS is lower than in the OS. Undoubtedly, it should lead to the conclusion that there exist some kind of mistake in the definition of the flow for the OS or, maybe, that an important modification of the original situation of th e river has been performed in a permanent way. Figure 5.17. Signs analysis f or the Remaining Reso urce Cost 5.10.4. Interpretation of the w ater cost signs from the Thermoeconomics perspective. River indices definitio n. From the previous analysis, and keeping in mi nd the exergy cost background given in Chapter 4, the considered water flow can be interpreted as an exergy flow carrying some valuable exergy, the fuel F, and some exergy that needs to be eliminate, the residue R. Chapter 5. Exergy assess ment in a wate r course: Physical Hydronomics Exergy cost assessm ent of water r esources: Physical Hydrono mics 236 The PH’s final objective is eliminating that R. In order to do it, external exergy sources need to be implemented, F R , i.e., the measures planning that has to be proposed. In particular, the idea can be summarized as Figure 5.18 indicates. P R b IM ,OS b OM,OS b OM , OS-FS b IM ,OS-FS P R b IM ,OS b OM,OS b OM , OS-FS b IM ,OS-FS Figure 5.18. Wate r stream as an exerg y flow The residue R can present a negative or a positive value depending on the considered parameter, but it does n ot affect the concep t of being a residue that n eeds to be eliminated from the water flow. The irreversib ility in the system is then given by th e residue and the exergy that is needed to invest in order to eliminate it (Eq. 5.19). In the considered water flow, a part of the residue to be eliminated is OM and the other one is IM (Eq. 5.20). Eq. 5.19. R R I F R → + * Eq. 5.20. R IM R OM R IM OM I F F R R → + + + * , * , Going further in this idea, some pure thermoeconomics index can be defined. First of all, it is worth to remember that there exist two basic exergy values within the river: the potential and the chemical potential. Currently, only th e potential component is exploited in hydro-electrical utilities. The chemical potential, although important and existing, is commonly ignored. In consequence, the index of potential use of the river (PURI, Eq. 5.21) and the index of chemical use of the river (CURI, Eq . 5.22) can be defined. They can be both understood as index of the productive process. Eq. 5.21. pot pot F P PURI = Where P pot represents the energy obtained from the facilities along the river course, in MWh/yr, and F pot stands for the existing potential in the watershed. This index, therefore, gives idea about how much of the potential is being used. Eq. 5.22. ch ch F P CURI = Chapter 5. Exergy assess ment in a wate r course: Physical Hydronomics Exergy cost assessm ent of water r esources: Physical Hydrono mics 237 Where P chem is the energy obtained from the facilit ies using the chemical potential of the water and F chem stands for the existing potential in the watershed. Currently, there is not any utility able to take advantage of the chemical exergy of the river and, in consequence, P chem is equal to cero in any river. Then, the chemical use index of rivers is, at the current technology state, null. In addition, an index related to de dissipative process can b e defined, the ratio on the residue R parameters. The residue i n the ri ver index (RRI) is the ratio between th e residue and the fuel used to eliminate that re sidue (Eq. 5.23). Nowadays, the OM is the factor determining the value of this index because it is the most representative parameter being eliminated in the WWTPs. Eq. 5.23. R F R RRI − = A secondary index can be additionally defined in order to obtain information about the fuel consumed to keep clean the river waters, in relation to the chemical potential in the river. That is the fuel-residue river index (FRRI), as Eq. 5.24 indicates. Eq. 5.24. chem R R F F RI F = 5.11. W ater quality modelling-Ri v er basin simulator s The water quality management strategy involv es a series of complex inter-disciplinary decisions based on speculated responses of water quality to changing controls (McIntyre and Wheater, 2004). The complex relationships between waste loads from different sources and the resulting water qualities o f the re ceiving waters are best described with mathematical models (Deksissa et al., 2004). 5.11.1. The necessity of a pressure-impacts model Article 36 of the WFD indicates that it is necessary t o undertake analyses of the characteristics of a river basin and the impa cts of human activity as well as an economic analysis of water use . The development in water status should be monitored by Member Stat es on a systematic and comparable basis throughout the Community. This information is necessary in ord er to provide a sound basis for Member States to develop programmes of measures ai med a t achieving the objectives established under this Directive. According to that section, in order to be able to determine the measurements th at would allow to reach the WFD’s objectives by 2015, and to include them in the Management Plan of the watershed, a previous analysis has to be performed. The consequences of the human activity (ant hropic pressures) affecting the environment (impacts) and possible measurements devoted to reduce them should be proposed and studied. [Document text truncated for crawler view.]