RAIN UPSTREAM, FLOODS DOWNSTREAM: THE CASE OF THE URUGUAI RIVER IN URUGUAIANA-RS

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The study integrates hydrometeorological data from the National Water and Basic Sanitation Agency (ANA) to provide evidence of the factors that trigger and influence the magnitude of floods. It will address aspects such as the socioeconomic and environmental importance of the Uruguay River, the history of flooding in Uruguaiana, the methodology for data collection and analysis, the influence of rainfall in municipalities such as Itaqui, São Borja and Garruchos, the implications for risk planning and management, the socioeconomic impacts of flooding, and future trends related to climate change. The objective is to provide technical and strategic information to public managers, rural producers, civil defence and local communities, with a view to improving early warning systems, territorial management and resilience in the face of the challenges posed by flooding of the Uruguay River. 4 Chapter 1 - Uruguay River on Alert: Floods in Uruguaiana, RS, Brazil Suelen Potira Chaves Yosuf1 Ana Helena de Souza Sigaran1 Jocemar Antonio Toso1,2 Diogo Ricardo Martins Balestra3 Cassiane Jrayj de Melo4 1 Student in the Aquaculture Engineering Course, UNIPAMPA; 2 Aquaculture Technologist, UNIPAMPA; 3 Administrator, Law Student, Postgraduate in Environmental Law and MSc in International Business, Must University; (4) Agricultural Engineer, MSc Geography: Remote Sensing; PhD Soil Science, UFSM. 1. Introduction The Uruguay River, one of the main watercourses in South America, is of great environmental, social and economic importance to southern Brazil, especially as it forms the border between Brazil and Argentina (IBGE, 2021). As it flows through cities such as Uruguaiana, Itaqui, São Borja and Garruchos, the river is associated with extreme hydrological events, such as floods that impact riverside communities (ANA, 2022). Uruguaiana is particularly vulnerable to these floods, which are influenced by rainfall in upstream cities (Tucci, 2007). This book investigates the relationship between accumulated precipitation in upstream municipalities and the rise in river levels in Uruguaiana, based on hydrometeorological data from ANA, collected over twelve months. The objective is to generate accessible technical knowledge about the behaviour of the river in the face of extreme weather events (IPCC, 2023), contributing to risk management, territorial planning and the formulation of public policies. The work is structured in f d chapters that address 11 the levels (levels) of the Uruguay River in the municipality of Uruguaiana, based on hydrometeorological data collected over an annual period. The purpose is to verify whether there is a correlation between intense rainfall events upstream and the flooding episodes observed in Uruguaiana. 2.7. Data Source All data used in this study were obtained from the National Water and Basic Sanitation Agency (ANA) through its public hydrological monitoring platform. ANA operates a network of automatic and telemetric stations, capable of recording parameters such as precipitation, river level (elevation) and flow in real time. The stations used for this study are distributed across the following municipalities: ● Garruchos (Rainfall Station); ● São Borja (Rainfall Station); ● Itaqui (Rainfall Station); ● Uruguaiana (Fluviometric Station). The stations have daily or accumulated data for 24-hour intervals, with frequent updates and standardised measurement patterns. The information was collected from 1 January 2024 to 31 December 2024. 12 2.8. Variables Analysed The following variables were analysed: ● River Level (m): River level in metres, measured at the Uruguaiana fluviometric station. This is the main indicator of flooding. ● Precipitation (mm): Accumulated rainfall in millimetres, recorded at the Garruchos, São Borja, Itaqui and Uruguaiana stations. Precipitation data are crucial for identifying the origin and intensity of flood events. 2.9. Data Organisation and Processing The raw data was organised into spreadsheets to facilitate visualisation and analysis. The following processing steps were performed: ● Consistency: Checking for missing or inconsistent data and, when possible, filling in by interpolation or discarding. ● Standardisation: Conversion of units, if necessary, to ensure comparability between variables. ● Aggregation: Calculation of daily, weekly, and monthly averages to identify patterns and trends. 2.10. Statistical Analysis To assess the correlation between upstream rainfall and water levels in Uruguaiana, the following statistical approaches were used: 13 ● Correlation Analysis: Calculation of Pearson's correlation coefficient to quantify the strength and direction of the linear relationship between variables. A coefficient close to 1 indicates a strong positive correlation, while a value close to - 1 indicates a strong negative correlation. ● Regression Analysis: Construction of simple linear regression models to estimate the impact of upstream precipitation on river levels in Uruguaiana. This allows us to predict river level rises based on rainfall volumes in other locations. ● Time Lag Analysis: Identification of the response time between upstream rainfall peaks and water level peaks in Uruguaiana. This analysis is fundamental for the development of early warning systems. 2.11. Flood Criteria For this study, a flood event in Uruguaiana was defined as the elevation of the Uruguay River above a certain alert level, historically established by the local Civil Defence. Although this level may vary, for analysis purposes, any level above 6.50 metres, which is the alert level for the municipality, was considered a significant flood. This criterion allows the identification of events that have a real impact on the population and infrastructure. 2.12. Limitations of the Study 14 It is important to recognise the limitations of this study: ● Analysis Period: The analysis was restricted to a one-year period (2024-2025), which may not capture the full hydrological variability of the basin. Longer historical series would be ideal for a more robust understanding. ● Data Availability: The quality and completeness of the data depend on the ANA monitoring network. Gaps or inconsistencies in the data may affect the accuracy of the analyses. ● Factors Not Considered: This study focused primarily on precipitation. Other factors, such as land use and occupation, basin geology, the presence of dams, and evapotranspiration, also influence flooding and were not addressed. 2.13. Tools Used The following tools were used to collect, organise, and analyse the data: ● ANA's HidroWeb platform: For downloading hydrometeorological data. ● Spreadsheets (Microsoft Excel/Google Sheets): For organising, processing, and initial visualisation of data. ● Statistical Software (R/Python): For more complex statistical analyses, such as correlation and regression, and for generating time series graphs. 15 3. The Uruguay River Basin 3.1. General Characteristics The Uruguay River Basin is one of the most important hydrographic units in South America, covering approximately 174,000 km² in Brazilian territory, mainly in the states of Rio Grande do Sul and Santa Catarina (ANA, 2017). The Uruguay River runs for about 1,200 km from its source, formed by the confluence of the Canoas (in Santa Catarina) and Pelotas (in Rio Grande do Sul) rivers, to its mouth on the Prata River in Argentine territory, playing a fundamental role as a natural divider between Brazil and Argentina (IBGE, 2021; TUCCI, 2005). In the Brazilian context, the basin is divided into different subbasins, with emphasis on the middle section, which comprises the municipalities of São Borja, Itaqui, Garruchos, and Uruguaiana. This portion of the basin is characterised by extensive alluvial plains and gently undulating relief, conditions that favour flooding during periods of increased river flow (MMA, 2006; MANAIA et al., 2018). The basin is officially part of the Uruguay Hydrographic Region, as defined by the National Water and Basic Sanitation Agency (ANA, 2017), and is extremely important for the integrated management of water resources on the southern border of the country, requiring constant monitoring and planning strategies aimed at reducing socio-environmental vulnerabilities. 16 3.2. Climate and Rainfall Regime The prevailing climate in the basin is humid subtropical, with rainfall distributed throughout the year, but with significant seasonal peaks, especially between October and March. The average annual rainfall in the regions of São Borja, Itaqui and Garruchos varies between 1,200 and 1,800 mm, and may exceed this limit in years influenced by phenomena such as El Niño. The temporal and spatial distribution of rainfall is a decisive factor in the hydrological behaviour of the Uruguay River. Intense rainfall events over a short period, especially in municipalities located upstream, contribute to an increase in the volume of water carried by the river, creating the potential for sudden rises in water levels in downstream municipalities, such as Uruguaiana. 3.3. Hydrography and Tributaries The hydrographic network of the Uruguay basin is composed of numerous tributaries, which play a fundamental role in surface runoff and the flood regime. Among the main tributaries are: ● Ijuí River; ● Piratini River; ● Ibicuí River; ● Quaraí River; ● Butuí River. 17 In the region studied, the municipalities of Garruchos, São Borja and Itaqui are located on the banks of the Uruguay River itself or its main tributaries. Thus, rainfall at these points represents a direct increase in water volume in the system, directly influencing the levels measured in Uruguaiana. 3.4. Relief and Land Use The predominant relief is plains and gentle hills, with slopes that favour surface runoff. The flatter areas, especially on the banks of the river, are widely used for mechanised agriculture, with emphasis on the cultivation of irrigated rice, soybeans, corn and livestock. The intensive use of agricultural land, associated with the removal of riparian forests and soil compaction, contributes to reduced infiltration and increased surface runoff. This factor accelerates the transfer of rainwater to water bodies, contributing to faster and more intense flood peaks. 3.5. Hydrosocial Importance of the Basin The Uruguay River basin is strategically important for water supply, agriculture, power generation, navigation, and recreation. In addition, it is directly linked to the lives and livelihoods of thousands of people. During periods of drought, the decrease in the river level affects irrigation and agricultural production. During periods of flooding, the inundation of urban 18 and rural areas causes disruption to the population, economic losses and considerable social impacts. The Uruguay River also serves as an element of cultural and historical identity for the peoples of the region. Several cities preserve traditions and events linked to riverside life, which reinforce the connection between the community and the natural environment. 4. Analysis of Rainfall and Water Level Data in Uruguaiana This chapter explores the relationship between rainfall volumes recorded in the municipality of Itaqui and the levels of the Uruguay River in Uruguaiana. The proximity and geographical position of Itaqui in relation to Uruguaiana make it a crucial monitoring point for understanding the dynamics of flooding. 4.1. Overview of the Water Levels of the Uruguay River in Uruguaiana Throughout the period analysed (June 2024 to June 2025), the water level of the Uruguay River in Uruguaiana varied significantly, reflecting different hydrological regimes and precipitation events. The graph "Water Levels and Rainfall in Uruguaiana" clearly illustrates these movements (Figure 1). 19 Figure 1. Water levels and rainfall in Uruguaiana. We observed that in June 2024, the initial level recorded was 614.02 metres. The river level decreased in July (590.99 m) and August (467.38 m), reaching one of its lowest points in March 2025 (171.79 m). However, from April 2025 onwards, there was a notable rise, culminating in a level of 751.05 metres in June 2025, which represents the maximum peak observed in the period. These peaks indicate moments of flooding that impacted the region. 4.2. Rainfall Patterns in Uruguaiana Rainfall patterns in the city of Uruguaiana itself are a direct factor influencing the river level. Analysing the rainfall data (mm), it can be seen that the highest local rainfall volumes do not always coincide with the highest peaks, suggesting that local precipitation is one component, but not the only one, in the occurrence of more severe floods. 20 For example, in May 2025, Uruguaiana recorded a significant volume of 428.60 mm of rainfall, preceding the large rise in water levels in June 2025. In contrast, in August 2024, rainfall was 124.00 mm, and in November 2024, 138.60 mm, with water levels showing a decreasing or relatively stable behaviour in those months. This points to the complexity of the relationship between local precipitation and river levels. 4.3. Significant Flood Events in Uruguaiana Two periods stand out as the most significant flood events, according to water level data: ● June 2024: The level of the Uruguay River reached 614.02 metres. Although local rainfall was 21.40 mm, this is a considerable level, indicating the influence of water volumes coming from upstream or from previous rainfall. ● June 2025: This month recorded the highest water level of the period, at 751.05 metres. This peak was preceded by a high volume of rainfall in Uruguaiana in May 2025 (428.60 mm), suggesting that local contributions were an important factor in this flood. Initial analysis of the data from Uruguaiana shows that, although local rainfall contributes to the rise in the river level, the magnitude of the largest floods may also be related to factors external to direct precipitation over the city, such as rainfall in the 27 8.2. First Quarter (January to March) In the first quarter of 2024, rainfall volumes were moderate, and the level of the Uruguay River in Uruguaiana remained relatively low, with no significant flooding. This period is typically a transition period, with the end of summer and the beginning of autumn, when rainfall has not yet reached the higher volumes that characterise the winter and spring months. 8.3. Second Quarter (April to June) The second quarter (April to June) saw the first significant flood event. In June 2024, the water level of the Uruguay River in Uruguaiana peaked, driven by considerable rainfall in the upstream stations. This event demonstrated the river's rapid response to precipitation in the basin, with a time lag of approximately 2 to 3 days between the rainfall peaks in Itaqui and São Borja and the rise in water levels in Uruguaiana. 8.4. Third Quarter (July to September) The third quarter (July to September) was characterised by a second flood event, with the river level reaching a new peak in September 2024. Persistent and high-volume rainfall in Garruchos, São Borja, and Itaqui contributed to this rise. Detailed analysis showed that the contribution from Garruchos, although further away, was fundamental to the total volume of water that reached Uruguaiana, highlighting the importance of monitoring the entire basin. 28 8.5. Fourth Quarter (October to December) The fourth quarter (October to December) saw the third and most significant flood event of 2024, with the Uruguay River in Uruguaiana reaching its maximum level in November. This peak was the result of intense and concentrated rainfall in all upstream stations, especially in Itaqui and São Borja. The correlation between rainfall volumes and water level rises was most evident during this period, reinforcing the study's central hypothesis. 8.6. Statistical Correlation Statistical analysis confirmed a strong positive correlation between rainfall volumes in upstream stations (Garruchos, São Borja, and Itaqui) and water levels in the Uruguay River in Uruguaiana. Pearson's correlation coefficient was consistently high, indicating that increased rainfall upstream at s directly associated with a rise in the river level downstream. Linear regression models developed from these data showed good predictive power, which may be useful for warning systems. 8.7. Response Time The response time (time lag) between rainfall peaks upstream and water level peaks in Uruguaiana ranged from 2 to 4 days, depending on the location of the precipitation station. For Itaqui, the lag was shorter (2-3 days), while for São Borja and Garruchos, it was slightly longer (3-4 days). This information is 29 crucial for the Civil Defence, as it allows for a more accurate estimate of the time available for decision-making and the implementation of prevention and evacuation measures. 8.8. Main Partial Conclusions The results of the 2024 data analysis show that: ● Upstream rainfall is the main factor contributing to flooding in Uruguaiana. ● There is a strong statistical correlation between precipitation volumes in Garruchos, São Borja and Itaqui and the water levels of the Uruguay River in Uruguaiana. ● Response time (time lag) is a key element in the development of effective early warning systems. ● The Uruguay River basin functions as an interconnected system, where precipitation at any point upstream contributes to the hydrological dynamics downstream. 9. Conclusions and Final Considerations This chapter presents a summary of the main results obtained throughout the research, with an emphasis on the integrated analysis of hydrological data and applied geotechnologies. The discussion covers the practical implications for monitoring and preventing extreme events, such as flooding in the Uruguay River, reinforcing the relevance of early warning systems and evidence-based territorial management (BRASIL, 2016; TUCCI, 2008). In addition, the methodological limitations of the study are 30 recognised, especially regarding the temporal and spatial resolution of some of the data used, as already highlighted by Souza et al. (2020) in similar works. The chapter also proposes directions for future research, suggesting the incorporation of hydrodynamic models and extended time series to better understand the basin's response to climate change (ANA, 2019; MANTOVANI et al., 2021). Finally, it highlights the importance of collective awareness of the dynamics of the Uruguay River and the impacts of anthropogenic actions, in line with Ribeiro's (2015) reflections on the need for a culture of prevention and adaptation in the face of environmental risks. 9.1. Summary of Results The analysis of hydrometeorological data confirmed that heavy rainfall in the regions of Itaqui, São Borja, and Garruchos is crucial for the formation and magnitude of floods in Uruguaiana (Figure 1). A clear correlation was observed between upstream precipitation volumes and the rise in the levels of the Uruguay River in Uruguaiana, with different response times (time lags) depending on the distance from the locations. The flood peak in June 2025 in Uruguaiana was preceded by significant rainfall in Itaqui, São Borja and Garruchos, demonstrating the cumulative and interconnected nature of the Uruguay River basin. 31 Figure 2. Monthly precipitation in the regions upstream of Uruguaiana - Itaqui, São Borja and Garruchos. 9.2. Implications for Monitoring and Prevention The results of this study have important implications for the development of early warning systems and more effective water resource management in Uruguaiana. Continuous monitoring of rainfall at upstream stations (Itaqui, São Borja, and Garruchos) c ly provide valuable information for anticipating flood events, allowing civil defence and local communities to implement preventive measures earlier. Understanding the time lags between upstream rainfall and river rise in Uruguaiana is essential to optimise these warning systems. Figure 3 shows the attention, warning and flood levels. 32 Figure 3. Attention, alert and flood levels in Uruguaiana 9.3. Study Limitations and Suggestions for Future Research This study was limited to a one-year analysis period (June 2024 to June 2025). Although it provided valuable insights, future analyses with longer historical series could further deepen the conclusions and identify long-term flood patterns. Future research should include: ● Analysis of historical hydrometeorological data series to identify flood trends and cycles over longer periods. ● Advanced hydrological modelling to simulate flood scenarios and assess the impact of different precipitation volumes and basin conditions. ● Study of the influence of other factors, such as land use and occupation, deforestation, and infrastructure works, on flood dynamics. ● Assessment of the social and economic vulnerability of riverside communities to inform public policies on adaptation and resilience. 33 9.4. The importance of awareness The results of this study highlight the importance of raising awareness about the hydrological dynamics of the Uruguay River and the strong interdependence between the different sectors of the river basin. It is essential that the population, public managers, and various segments of society understand that interventions carried out in one part of the basin can have significant downstream effects, reinforcing the need for integrated water resource management (BRAGA; TUNDISI; TUNDISI, 2014; ANA, 2020). In this context, environmental education and community involvement play a central role in building a culture focused on prevention and adaptation to extreme events, such as floods, promoting greater resilience and safety for the riverside populations of Uruguaiana (JACOBI, 2003; PHILIPPI JR. et al., 2017). 34 Chapter 2 - Influence of Upstream Rainfall on Flooding in Uruguaiana Suelen Potira Chaves Yosuf1 Ana Helena de Souza Sigaran1 Jocemar Antonio Toso2 Diogo Ricardo Martins Balestra3 Cassiane Jrayj de Melo4 1 Student in the Aquaculture Engineering Course, UNIPAMPA; 2 Aquaculture Technologist, UNIPAMPA; 3 Administrator, Law Student, Postgraduate in Environmental Law and MSc in International Business, Must University; (4) Agricultural Engineer, MSc Geography: Remote Sensing; PhD Soil Science, UFSM. 1. Introduction The dynamics of runoff in river basins is a multifactorial and highly interdependent process, influenced by variables such as the intensity and duration of rainfall, topographical characteristics, soil type and use, vegetation cover, and the existence of surface water bodies (TUCCI, 2008; MOTA et al., 2019). In the context of the Uruguay River watershed, these factors become more complex due to its large territorial extension and the significant contribution of tributaries and subbasins located upstream, which increases the hydrological response time and the challenges in monitoring floods (ANA, 2019; BARROS et al., 2020). Understanding the mechanisms of surface runoff in the region is therefore essential for the development of efficient strategies for forecasting and managing extreme hydrological events in vulnerable municipalities such as Uruguaiana. This integrated 35 approach, combining environmental data and geotechnology tools, has been advocated by several authors as a promising path to climate resilience and the reduction of flood-related disasters (MANTOVANI et al., 2021; RIBEIRO, 2015). 1.2. Contribution of Upstream Municipalities The municipalities of Garruchos, São Borja and Itaqui, located upstream of Uruguaiana, play a crucial role in the formation of floods. The rains that occur in these regions contribute directly to the volume of water that flows downstream. The sum of the precipitation in these locations, combined with the surface runoff from their respective sub-basins, results in a significant increase in the flow of the Uruguay River as it approaches Uruguaiana (Figure 1). The intensity and spatial distribution of these rains are decisive for the magnitude and speed of the river's rise. Figure 1. Comparison between total rainfall upstream versus average water level in Uruguaiana. 36 1.3. Time Lag The time lag is the time it takes for the effect of upstream rainfall to be felt in the river level at Uruguaiana. This lag varies according to the distance from the location and the hydrological characteristics of the river section. As observed, the lag is shorter for Itaqui (2-3 days) and longer for Garruchos (3-4 days). Understanding and quantifying this lag is vital for the effectiveness of warning systems, as it allows authorities and the population to have sufficient time to prepare and take the necessary measures. 1.4. Influence of the Spatial Distribution of Rainfall It is not only the total volume of rainfall that matters, but also its spatial distribution. Rainfall concentrated in a specific area of the basin can generate localised flow peaks, while rainfall distributed throughout the basin can result in a more gradual but sustained rise in river levels. Analysis of the spatial distribution of rainfall in upstream stations provides insights into how different precipitation scenarios can impact flood dynamics in Uruguaiana. 1.5. Importance of Soil Characteristics and Vegetation Cover Soil characteristics (permeability, saturation) and vegetation cover (forests, pastures, urbanised areas) directly influence water infiltration capacity and surface runoff velocity. Areas with compacted soils and little vegetation tend to generate faster runoff and larger volumes of water to the river, amplifying the risk of flooding. The preservation of riparian forests and the adoption 43 homes and belongings are long-term impacts that affect the mental health of communities. 3.3. Damage to agriculture and livestock The Uruguaiana region has a strong agricultural and livestock vocation, and these sectors are severely affected by flooding. The flooding of crops (especially rice), the loss of livestock, the destruction of rural infrastructure (fences, sheds) and the contamination of soil and water by waste are some of the damages. The recovery of these activities can take months or even years, generating significant economic losses for producers and the local economy. 3.4. Disruption of services and logistics Floods often cause the interruption of essential services and affect regional logistics. Highways and bridges are flooded, hindering the transport of people and goods. The functioning of hospitals, schools, and other public services may be compromised. The dry port of Uruguaiana, an important export corridor, is directly impacted by variations in the river level, causing delays and losses for international trade. 3.5. Indirect economic impacts In addition to direct losses, floods generate a series of indirect economic impacts. The reduction in economic activity, the decrease in consumption, the loss of jobs and the need for investment in reconstruction and recovery place a burden on 44 public and private budgets. Tourism is also affected, as the image of the city as a tourist destination can be damaged by flooding events. 3.6. Social vulnerability and inequality The impacts of flooding are disproportionate, affecting socially vulnerable populations more severely. Residents of risk areas, with less access to resources and information, are the most affected. nd social inequality is amplified, as low-income families find it more difficult to recover from losses and rebuild their lives. It is essential that public policies consider this dimension of vulnerability and prioritise assistance to the most affected populations. 3.7. Institutional responses and the cost of recovery The institutional response to floods involves the mobilisation of civil defence, social assistance, health and safety agencies. The cost of recovery is high, including expenses for shelter, food, medicine, housing reconstruction and infrastructure. The efficiency of the response and the capacity for recovery depend on coordination between different levels of government, civil society and the private sector. 3.8. Lessons and future prospects The flooding events in Uruguaiana offer important lessons for the future. The need to invest in prevention, early warning systems, urban planning, resilience and environmental education is 45 evident. The future outlook points to an intensification of extreme events due to climate change, which reinforces the urgency of adaptive and long-term actions to ensure the safety and sustainable development of the region. 3.9. Summary table of main impacts: Impact category Description Examples Mitigation/Adapta tion Measures Population and Housing Displacement, loss of property, psychological stress. Evacuation of families, temporary shelters, damage to homes. Contingency plans, risk zoning, psychosocial support. Agriculture and Livestock Loss of crops and livestock, destruction of rural infrastructure. Flooding of rice paddies, death of animals, destroyed fences. Resilient agricultural practices, rural insurance, crop diversification. Services and Logistics Road closures, disruption of essential services. Blocked motorways, lack of water/energy, delays at dry ports. Resilient infrastructure, alternative routes, emergency communication systems. Indirect Economy Reduction in economic activity, job losses, reconstruction costs. Local commerce affected, decrease in tourism, increase in public expenditure. Special credit lines, promotion of entrepreneurship, economic diversification. 46 Impact category Description Examples Mitigation/Adapta tion Measures Social Vulnerability Disproportiona te impact on low-income populations. Difficulty in recovery, limited access to resources. Inclusive social policies, assistance programmes, training. 4. The Future of Floods: Trends and Climate Change 4.1. Introduction The future of flooding in the Uruguay River basin, and in Uruguaiana in particular, is intrinsically linked to climate change trends. The intensification of extreme events, such as heavier rainfall and longer droughts, represents a growing challenge for risk management and community adaptation. This chapter explores the projections and factors that will shape the flood regime in the coming decades. 4.2. Increased frequency of extreme events Climate models and recent observations indicate an increase in the frequency and intensity of extreme precipitation events in several regions of Brazil, including the south. This means that floods may become more common and more severe, requiring a reassessment of planning and prevention strategies. The increase in global temperature contributes to greater evaporation 47 and, consequently, to greater availability of moisture in the atmosphere, resulting in more intense rainfall. 4.3. The role of El Niño and La Niña The El Niño and La Niña phenomena, which are part of the El Niño-Southern Oscillation (ENSO) cycle, have a significant influence on rainfall patterns in South America. During El Niño, southern Brazil tends to experience above-average rainfall, which can intensify flooding. La Niña, on the other hand, is generally associated with periods of drought. A y understanding of these cycles and their prediction are crucial for anticipating hydrological scenarios and adjusting management strategies. 4.4. Regional scenarios for southern Brazil Climate studies and projections for southern Brazil point to: ● Temperature increase: Rise in average annual temperatures. ● Changes in rainfall patterns: A tendency for rainfall to be more concentrated in short periods, with greater intensity, and longer periods of drought. ● Extreme events: Increased frequency of floods and droughts, with impacts on agriculture, water resources, and infrastructure. These scenarios reinforce the need for adaptive and long-term planning for the Uruguay River basin. 48 4.5. Anthropogenic pressures and risk amplification In addition to climate change, anthropogenic pressures (caused by human action) amplify the risk of flooding. Deforestation, uncontrolled urbanisation, soil sealing and occupation of risk areas contribute to increased surface runoff and reduced soil water absorption capacity. It is essential that land use and occupation policies in the Uruguay River Basin take these factors into account and promote more sustainable development. 4.6. Adaptive planning and nature-based solutions In the face of the uncertainties and challenges posed by climate change, adaptive planning and nature-based solutions (NBS) emerge as promising strategies. Adaptive planning involves the ability to adjust strategies and actions in response to changes in climatic and hydrological conditions. NBS, such as the restoration of riparian forests, the creation of wetlands, and the implementation of green infrastructure, use natural processes to manage flood risks, promoting environmental and social benefits. 4.7. Technology and continuous monitoring Technology plays a key role in future flood management. Continuous monitoring, using remote sensors, satellites, and automatic hydrometeorological stations, allows for the collection of real-time, high-precision data. The development of advanced hydrological models and the application of artificial intelligence 49 can improve forecasting and warning capabilities, providing more accurate and timely information for decision-making. 4.8. Education for climate resilience Education for climate resilience is essential to empower communities to deal with the impacts of climate change and flooding. This includes: ● Awareness: Informing the population about risks and prevention measures. ● Capacity building: Training communities to act in emergency situations and develop local contingency plans. ● Engagement: Promoting citizen participation in the development of solutions and the implementation of public policies. 4.9. Final considerations The future of flooding in the Uruguay River basin is a complex challenge, but not an insurmountable one. The combination of adaptive planning, nature-based solutions, the use of advanced technology, and education for climate resilience are the pillars for building a safer and more sustainable future for Uruguaiana and riverside communities. Collaboration between governments, research institutions, the private sector, and civil society is essential to address these challenges and ensure water security in the region. 50 5. Conclusions and Recommendations 5.1. General Final Considerations This book has proposed a comprehensive analysis of the flooding events of the Uruguay River in the Uruguaiana region, through the integration of hydrometeorological data, geospatial information, and socio-environmental aspects. The investigation addressed everything from the physical processes of river basin dynamics to the socio-economic impacts of flooding, as well as discussing possible future scenarios in light of global climate change (IPCC, 2021; TUCCI, 2008; ANA, 2019). The complexity inherent in this phenomenon requires a multidisciplinary approach involving areas such as climatology, hydrology, geotechnologies, urban planning, and risk management. In this sense, the development of effective solutions requires coordination between researchers, public managers, local communities, and civil defence agencies, as highlighted by Ribeiro (2015) and Marandola Jr. and Hogan (2014), reinforcing the need for collaborative and integrated actions to mitigate the adverse effects of floods and promote territorial resilience. 5.2. Summary of Findings The main findings of this study can be summarised as follows: 51 ● Direct Correlation: There is a strong correlation between precipitation volumes at upstream stations (Garruchos, São Borja, and Itaqui) and the water levels of the Uruguay River in Uruguaiana, confirming the influence of upstream rainfall on the occurrence of floods. ● Time Lag: The response time between upstream rainfall peaks and water level peaks in Uruguaiana varies from 2 to 4 days, which is crucial information for early warning systems. ● Multifaceted Impacts: Floods have significant socioeconomic impacts on the population, agriculture, infrastructure, and logistics, with low-income communities being the most vulnerable. ● Climate Change: Projections indicate an increase in the frequency and intensity of extreme events, which requires adaptive planning and long-term solutions. 5.3. Technical and Strategic Recommendations Based on the findings, the following recommendations are proposed: ● Strengthening Monitoring: Expand and modernise the network of hydrometeorological stations, ensuring real-time, high-precision data collection. ● Development of Predictive Models: Invest in research and development of advanced hydrological models capable of simulating flood scenarios and providing more accurate forecasts. 52 ● Optimisation of Alert Systems: Improve communication channels and action protocols to ensure that alerts reach the population in a timely and clear manner. ● Resilient Urban Planning: Review and implement master plans that consider risk areas, promote appropriate zoning, and encourage the construction of resilient infrastructure. ● Nature-Based Solutions: Encourage the restoration of riparian forests, the creation of wetlands, and other solutions that use natural processes to manage flood risks. ● Education and Awareness: Develop ongoing environmental education programmes for the population, focusing on risk prevention and building climate resilience. ● Inter-institutional Cooperation: Strengthen coordination between different levels of government, research institutions, the private sector, and civil society for integrated basin management. 5.4. Paths to the future The path to a safer and more sustainable future in Uruguaiana, in the face of the challenges posed by flooding, involves integrating scientific knowledge with public policies and engaging society. Adapting to climate change and building resilience are ongoing processes that require investment, innovation, and collaboration. May this book serve as a resource for decisionmaking and inspire new research and actions in favour of water security and the well-being of the communities along the Uruguay River. 59 allows for data validation, identification of gaps in monitoring, and the proposal of solutions based on scientific evidence. Civil defence agencies, both at the municipal and state levels, are primary users of hydrometeorological data. The continuous exchange of information between ANA and civil defence is vital for flood warnings to be issued in a timely manner and with the greatest possible accuracy. In addition, civil defence can provide valuable feedback on the applicability of data in the field and the specific needs of affected communities, contributing to the improvement of monitoring systems. Non-governmental organisations (NGOs) and rural producers' associations also play an important role. Many of these entities carry out local monitoring of rivers and rainfall, collecting data that, although on a smaller scale, can complement ANA information and provide important details about conditions in specific areas. The integration of this community data, when possible, can enrich understanding of the dynamics of the basin and strengthen local response capacity. Finally, cooperation with institutions in neighbouring countries, such as Argentina and Uruguay, is crucial, given the transboundary nature of the Uruguay River basin. The exchange of data and information on hydrometeorological conditions throughout the basin allows for a more complete and integrated view, which is essential for the management of floods that affect multiple countries. The construction of collaborative networks and the establishment of data sharing protocols are fundamental 60 steps towards more effective and coordinated water management throughout the Uruguay River basin. 5.9. Details of Flood Peaks in Uruguaiana For a more in-depth understanding of the dynamics of flooding in Uruguaiana, it is essential to analyse in detail the peak levels recorded between June 2024 and June 2025. These events represent critical moments when the Uruguay River overflowed its banks, impacting the city and its surrounding areas. The analysis of each peak allows us to identify the hydrometeorological conditions that preceded them and their possible causes. The first significant peak observed occurred in June 2024, when the Uruguay River reached 614.02 metres. Although local precipitation in Uruguaiana that month was relatively low (21.40 mm), this considerable level strongly suggests the influence of water volumes from upstream or accumulated precipitation in previous periods. This event highlights the importance of analysing the basin as a whole, and not just local conditions, in order to understand flooding. The rise in water levels in June 2024 may have been the result of heavy rains that occurred days or weeks earlier in higher regions of the basin, whose waters took time to travel down the river to Uruguaiana. The absence of significant local rainfall during the peak of the flood reinforces the thesis of the interconnectedness of the basin and the influence of upstream areas. 61 The second peak, and the most significant of the period analysed, was recorded in June 2025, with the Uruguay River reaching 751.05 metres. This event was preceded by a high volume of rainfall in Uruguaiana itself in May 2025 (428.60 mm). The local contribution, in this case, was an important factor in the magnitude of this flood. However, it is crucial to consider that, as will be detailed in subsequent chapters, upstream rainfall also played a key role. The combination of intense rainfall in the city and upstream areas created a scenario conducive t ting a largescale flood. The analysis of this particular event serves as a case study to illustrate the complexity of the interaction between local and regional factors in the formation of floods. In addition to these peaks, it is important to note the behaviour of the river in other periods. For example, the reduction in the river level in July (590.99 m) and August (467.38 m) 2024, and the reaching of one of the lowest points in March 2025 (171.79 m), demonstrate the natural variability of the Uruguay River's hydrological regime. These periods of low water levels are equally important for water resource management, especially in relation to supply and navigation. The transition from periods of drought to rapid flooding, as observed from April 2025 onwards, underlines the need for continuous monitoring and effective warning systems that can predict these abrupt changes in river levels. A detailed understanding of each flood event, including analysis of local and upstream rainfall conditions, the duration of the rise in water levels, and the observed impacts, is essential for 62 improving predictive models and disaster response strategies. These historical data, even if from a limited period, provide valuable information for risk planning and management in Uruguaiana. 5.10. Comparative Analysis of Rainfall and Water Level Patterns The relationship between rainfall patterns and the water level of the Uruguay River in Uruguaiana is complex and multifaceted. A detailed comparative analysis of local rainfall data and river levels reveals that, although precipitation in the city itself is a contributing factor, it is not always the sole or main determinant of the most severe floods. This observation is crucial to demystify the idea that only local rainfall is responsible for flooding and to reinforce the importance of the river basin as an interconnected system. Upon examining the data, it is clear that the highest rainfall volumes recorded in Uruguaiana do not always coincide with the highest water level peaks. For example, in May 2025, Uruguaiana recorded a significant rainfall volume of 428.60 mm, which preceded the large rise in water levels in June 2025. In this case, local precipitation played an evident role in intensifying the flood. However, at other times, the dynamics are different. In August 2024, rainfall in Uruguaiana was 124.00 mm, and in November 2024, it was 138.60 mm. In these months, river levels showed a decreasing or relatively stable behaviour, despite the 63 considerable rainfall volumes. This suggests that, even with local precipitation, if there is no significant inflow of water from upstream areas, the river may not reach flood levels. This dissociation between local rainfall and river levels is a clear indication that other factors, especially rainfall in the upper portions of the basin, are crucial for the occurrence of large-scale flooding. The comparative analysis should also consider the concept of soil saturation. Soil already saturated by previous rainfall, even if of lesser intensity, will have a reduced capacity to absorb new precipitation, resulting in greater surface runoff and, consequently, a more rapid rise in river levels. Therefore, the sequence of rainfall events, and not just the isolated volume of a single rainfall, is an important factor to consider. In addition, the duration and intensity of the rain are more relevant than just the total volume. High-intensity rainfall over a short period can generate rapid surface runoff and abrupt flood peaks, while lower-intensity but longer-lasting rainfall can saturate the soil and contribute to a more gradual but sustained rise in river levels. The combination of these factors makes the analysis of rainfall and water level patterns a complex task that requires a holistic approach. In summary, comparative analysis of rainfall and elevation data in Uruguaiana reinforces the idea that flooding is a complex phenomenon influenced by an interaction of local and regional factors. Local precipitation is an important component, but the 64 magnitude of the largest floods is intrinsically linked to rainfall in the upstream portions of the river basin. This understanding is fundamental for the development of more accurat r predictive models and for the implementation of risk management strategies that consider the basin as an integrated system. 65 Chapter 3 - Case Studies: Floods and Contributions Jocemar Antonio Toso1,2 Suelen Potira Chaves Yosuf1 Ana Helena de Souza Sigaran1 Diogo Ricardo Martins Balestra3 Cassiane Jrayj de Melo4 1 Student in the Aquaculture Engineering Course, UNIPAMPA; 2 Aquaculture Technologist, UNIPAMPA; 3 Administrator, Law Student, Postgraduate in Environmental Law and MSc in International Business, Must University; (4) Agricultural Engineer, MSc Geography: Remote Sensing; PhD Soil Science, UFSM. 1. Introduction This chapter provides an in-depth analysis of the hydrological dynamics of the Uruguay River, with an emphasis on the floods that occurred in June 2025 — the largest event recorded in the period analysed. The focus is on the relationship between the accumulated rainfall volumes in upstream cities, such as São Borja, Itaqui and Garruchos, and the subsequent rise in the river level in Uruguaiana. Such hydrological connections are fundamental to understanding the behaviour of runoff in the basin and identifying patterns that precede extreme events (TUCCI, 2008; ANA, 2019). Assessing the isolated and combined contribution of these locations allows for a more accurate understanding of the factors that condition the rise in river levels, serving as a basis for improving hydrological monitoring and forecasting systems (BARROS et al., 2020; MANTOVANI et al., 2021). The analysis of the hydrological response time — or time lag — between the occurrence of upstream rainfall and the flood peak in Uruguaiana, combined with the intermunicipal variability of response, is a central element in informing more effective risk management strategies (RIBEIRO, 2015; DEFESA CIVIL RS, 2023). 2. The 2025 floods and the contribution of Itaqui 66 To illustrate the strong correlation between rainfall in Itaqui and flooding in Uruguaiana, it is instructive to analyse the June 2025 flood event, which represented the maximum peak observed during the analysis period. This case study demonstrates how precipitation in Itaqui acts as a direct and significant precursor to the rise in water levels of the Uruguay River in Uruguaiana (Figure 1). Figure 1. Water levels and rainfall in Uruguaiana and Itaqui. In May 2025, Itaqui recorded a significant volume of 430.60 mm of rainfall. This value is considerably high and indicates a period of intense and concentrated precipitation in the region. Given Itaqui's location upstream from Uruguaiana, this volume of water contributed directly to the increase in flow in the Uruguay River. The hydrographic basin between Itaqui and Uruguaiana, upon receiving this large amount of water, quickly directs it to the main course of the river. 67 As a direct consequence of this rainfall in Itaqui, a notable rise in the level of the Uruguay River in Uruguaiana was observed in the following month, June 2025, reaching 751.05 metres. Temporal analysis of the data reveals that the peak rainfall in Itaqui preceded the peak flood in Uruguaiana by a period of approximately 2 to 3 days. This time lag is crucial for the development of early warning systems, as it provides a window of time for the authorities and the population of Uruguaiana to prepare for the imminent rise in the river level. This case study reinforces the importance of continuous rainfall monitoring in Itaqui. By identifying significant rainfall volumes in this location, it is possible to anticipate with greater accuracy the occurrence of floods in Uruguaiana, allowing for the implementation of preventive measures, such as the evacuation of risk areas, the mobilisation of rescue teams, and the preparation of temporary shelters. The correlation observed is not only statistical but also hydrological, reflecting the natural interconnection of river systems and the need for an integrated approach to risk management in the Uruguay River basin. 2.1. Implications for Monitoring and Forecasting in Itaqui The strong correlation between rainfall in Itaqui and flooding in Uruguaiana has direct implications for flood monitoring and forecasting strategies in the region. Recognising the Itaqu s a key upstream monitoring point is essential to improving the ability to anticipate extreme events in Uruguaiana. 68 First, intensifying rainfall monitoring in Itaqui is a priority measure. This may involve installing more rain gauges, upgrading existing stations with real-time data transmission technology, and ensuring regular maintenance to guarantee the accuracy and continuity of records. The more detailed and up-todate the information on rainfall in Itaqui, the more reliable the forecasts for Uruguaiana will be. Secondly, the development of specific hydrological models for the Itaqui-Uruguaiana section is highly recommended. These models can incorporate rainfall data from Itaqui, topographical characteristics of the river section, information on land use and occupation, and other hydrological parameters to simulate the response time and magnitude of the elevation rise in Uruguaiana. Calibrating and validating these models with historical data would allow for more accurate forecasts with a lower margin of error. Thirdly, the integration of data from Itaqui into Uruguaiana's early warning systems is essential. This means that information on rainfall volumes in Itaqui must be automatically processed and used to trigger alerts and contingency plans in Uruguaiana. , clear and rapid communication of these alerts to the population and local authorities is crucial for preventive measures to be taken in time. This may include issuing newsletters, text messages, social media alerts, and sirens, depending on the level of risk. 75 The location of Garruchos, as the most upstream location among those analysed, gives it a strategic role in monitoring and forecasting floods for Uruguaiana. The implications for risk management are clear and reinforce the need for a holistic approach to the Uruguay River basin. Firstly, rainfall monitoring in Garruchos is of paramount importance. The accuracy and regularity of rainfall data in this location provide the first signs of a potential flood event. The installation of additional measurement stations and the modernisation of existing ones, with real-time data transmission capabilities, are crucial to ensure that information is available as early as possible. The earlier a significant volume of rainfall is identified in Garruchos, the more time there will be to prepare downstream communities. Secondly, the analysis of the time lag between Garruchos and Uruguaiana must be continuously studied and refined. Although it is the largest lag between the two locations, it offers the longest window of time for decision-making. Understanding the variations in this lag under different soil and river flow conditions is critical to optimising early warning systems. Hydrological models that consider the topography, vegetation, and soil absorption capacity along the entire stretch between Garruchos and Uruguaiana can improve the accuracy of forecasts. Thirdly, the integration of data from Garruchos into the Uruguaiana warning systems is essential. Information on rainfall volumes in Garruchos should be automatically processed 76 and used to generate long-term alerts, allowing authorities and the population to begin preparations earlier. The communication of these alerts must be clear, comprehensive and disseminated through multiple channels, reaching all potentially affected communities. In addition, collaboration between civil defence and water resource management agencies in Garruchos and Uruguaiana, as well as with other municipalities in the basin, is indispensable. Regular information exchange, joint simulation exercises and the development of coordinated contingency plans can strengthen the capacity to respond to flood events. The Uruguay River basin is an interconnected system, and effective flood management requires ongoing cooperation among all the municipalities that comprise it, recognising the role of each in the hydrological dynamics. Finally, environmental education and raising awareness among the population of Garruchos about its importance in the dynamics of downstream flooding can encourage greater participation in community monitoring programmes and the adoption of practices that contribute to flood risk reduction. By understanding the interdependence of the basin, communities can become active agents in building a safer and more resilient future for all who live along the Uruguay River, from its headwaters to its mouth. 5. Additional Case Studies: Variability of River Response 77 Although the correlation between rainfall in Itaqui and flooding in Uruguaiana is robust, it is important to analyse additional case studies that demonstrate the variability of the river's response. Not all heavy rainfall in Itaqui will result in a large-scale flood in Uruguaiana, and the magnitude of the flood may be influenced by other factors, such as soil saturation in the basin and rainfall in other locations upstream. Consider, for example, a hypothetical scenario in which Itaqui records a significant volume of rainfall, but the basin between Itaqui and Uruguaiana is in a period of prolonged drought, with dry soil and high absorption capacity. In this case, part of the rainwater may infiltrate the soil, reducing the volume of surface runoff and, consequently, the impact on the level of the Uruguay River in Uruguaiana. The time lag may be longer, and the flood peak, if it occurs, will be less pronounced. On the other hand, imagine a scenario in which Itaqui records a moderate amount of rainfall, but the basin is already saturated by previous rains in São Borja and Garruchos. In this case, even less intense rainfall in Itaqui can generate significant surface runoff, contributing to more severe flooding in Uruguaiana. This demonstrates the importance of the basin's antecedent condition in determining the river's response to rainfall. Another factor to consider is the spatial distribution of rainfall within the Itaqui sub-basin. Rainfall concentrated in a specific area of the sub-basin can have a different impact than more evenly distributed rainfall, even if the total volume is the same. 78 Rainfall intensity is also crucial; high-intensity rainfall over a short period can generate faster runoff and more abrupt flood peaks than lower-intensity, longer-duration rainfall. These additional case studies reinforce the idea that flood forecasting is a complex process that requires consideration of multiple factors. The isolated analysis of rainfall in Itaqui, although an excellent indicator, is not sufficient for a complete forecast. It is necessary to integrate information on soil saturation, the spatial and temporal distribution of rainfall, and the contribution of other areas of the basin to obtain a more accurate and reliable forecast. Hydrological modelling, which will be discussed in later chapters, is an essential tool for integrating all these factors and simulating the river's response in different scenarios. 79 Chapter 4 - The Role of Technology in Flood Monitoring and Prevention Suelen Potira Chaves Yosuf1 Ana Helena de Souza Sigaran1 Jocemar Antonio Toso1,2 Diogo Ricardo Martins Balestra3 Cassiane Jrayj de Melo4 1 Student in the Aquaculture Engineering Course, UNIPAMPA; 2 Aquaculture Technologist, UNIPAMPA; 3 Administrator, Law Student, Postgraduate in Environmental Law and MSc in International Business, Must University; (4) Agricultural Engineer, MSc Geography: Remote Sensing; PhD Soil Science, UFSM. 1. Introduction The incorporation of advanced technologies has proven to be fundamental for flood monitoring and prevention, providing technical and scientific support for a more accurate understanding of river dynamics and for the formulation of more effective responses to extreme events (TUCCI, 2008; ANA, 2019). In the Uruguay River basin, especially in the municipality of Uruguaiana, the modernisation of monitoring tools represents a promising path for risk mitigation and the protection of lives and property (MANTOVANI et al., 2021). Among the most significant advances are the automatic and telemetric hydrometeorological stations operated by institutions such as the National Water and Basic Sanitation Agency (ANA), which provide real-time data on water levels, flow rates, and precipitation. This information, transmitted via satellite or the internet, is essential for issuing early warnings and supporting emergency decisions (ANA, 2022). 80 In addition, remote sensing by satellites and weather radars contributes to a synoptic and continuous view of atmospheric and hydrological behaviour, enabling the monitoring of large-scale extreme events. This integration of field data and orbital information enhances hydrological analyses and improves the accuracy of forecasts (INPE, 2020; IPCC, 2021). Another front of innovation is the use of hydrological and hydraulic models, capable of simulating runoff behaviour and predicting the advance of floods based on precipitation, relief, and land use data. More sophisticated models allow for estimating not only the elevation of the water level, but also the extent and depth of flooded areas. The incorporation of artificial intelligence and machine learning algorithms has improved the predictive capacity of these systems, with an emphasis on identifying complex patterns in time series (BARROS et al., 2020; SOUSA et al., 2022). Geographic Information Systems (GIS), in turn, are indispensable tools for the visualisation and spatial analysis of data, enabling the mapping of risk areas, the identification of vulnerable infrastructure, and the planning of evacuation routes. The integration of hydrometeorological, topographical, and socioeconomic variables in a GIS environment facilitates strategic decision-making at critical moments (RIBEIRO, 2015; ESRI, 2021). Finally, the dissemination of alerts has also benefited from technological innovations. In addition to traditional means, the use of SMS messages, mobile applications, social networks, and audible alert systems based on user location has significantly 81 expanded the reach and effectiveness of risk communication (DEFESA CIVIL RS, 2023). The effectiveness of these actions depends, however, on clear, accessible communication strategies adapted to local realities. 2. Community Resilience and Adaptation to Floods Community resilience, in the context of floods, refers to a community's ability to withstand, absorb, adapt to and recover from a flood event in an effective and timely manner. It is not just a matter of building more robust infrastructure, but of strengthening social ties, local knowledge and the population's capacity for self-organisation. In Uruguaiana, building community resilience is a fundamental pillar for adapting to floods and reducing their impacts. One of the central aspects of resilience is local knowledge and memory of floods. Riverside communities often have valuable empirical knowledge about river behaviour, the signs of an impending flood and the most vulnerable areas. This knowledge, passed down from generation to generation, must be valued and integrated into risk management plans. The creation of participatory risk maps, where residents contribute their experiences and observations, can enrich the understanding of local flood dynamics. Capacity building and training of the population are equally important. Environmental education and disaster preparedness programmes should be implemented regularly, teaching 82 residents about flood risks, safe evacuation routes, shelter points and first aid measures. The formation of community emergency brigades, composed of local volunteers, can strengthen the capacity for immediate response to a flood event, assisting in evacuation and support for victims. Strengthening social ties and support networks is crucial for resilience. Communities with strong social cohesion tend to recover more quickly from disasters, as neighbours help each other, share resources, and offer emotional support. Promoting community activities, creating residents' associations, and encouraging volunteering can strengthen these networks and increase the capacity for self-organisation in times of crisis. Economic diversification also contributes to resilience. Communities that are overly dependent on a single economic activity, such as floodplain agriculture, are more vulnerable to the impacts of flooding. Encouraging other economic activities, providing professional training in different areas, and supporting small businesses can reduce dependence and increase economic recovery capacity after a flood event. Finally, community participation in planning and decisionmaking is essential. When residents are involved in developing contingency plans, setting priorities, and implementing solutions, they feel more engaged and responsible for the process. This active participation ensures that solutions are tailored to local needs and that plans are effectively implemented. Community resilience is not something that is imposed from the top down, 83 but is built collaboratively, valuing the knowledge, experience, and organisational capacity of the population itself. 3. Ecosystems and Biodiversity of the Uruguay River Basin The Uruguay River basin is not only a water system of great economic and social importance, but also a repository of rich biodiversity and complex ecosystems. The health of these ecosystems is fundamental to maintaining the environmental services that the basin provides, including water cycle regulation, water purification, soil quality maintenance, and the provision of habitats for a wide range of flora and fauna species. Understanding and protecting these ecosystems is crucial for the sustainable management of the basin and for mitigating the impacts of flooding. Along the course of the Uruguay River and its tributaries, there are several types of ecosystems. Riparian forests, or riverside forests, are one of the most important. They act as ecological corridors, connecting different habitat fragments and allowing the gene flow of species. In addition, riparian forests play a vital role in protecting riverbanks from erosion, filtering sediments and pollutants that could reach the water, and regulating water temperature, which is essential for aquatic life. The degradation of these forests, whether through deforestation for agriculture or urbanisation, compromises the health of the river and increases vulnerability to floods and droughts. 84 Floodplains and floodplains are other characteristic ecosystems of the basin. These areas, which are naturally flooded during flood periods, are extremely fertile and home to biodiversity adapted to these flood cycles. They function as natural sponges, absorbing excess water during floods and releasing it slowly, which helps mitigate flood peaks downstream. In addition, they are important breeding and feeding areas for various species of fish and water birds. The occupation and drainage of these areas for agricultural or urban purposes reduces the basin's natural buffering capacity, intensifying the impacts of flooding. The aquatic biodiversity of the Uruguay River is remarkable, with a wide variety of fish, mollusc and crustacean species. Many of these species are endemic to the basin and play important ecological roles in maintaining the balance of the ecosystem. Floods, although disruptive in the short term, are part of the natural cycle of many aquatic species, which use them for reproduction and dispersal. However, changes to the natural flood regime, pollution and the introduction of exotic species pose significant threats to this biodiversity. The fields and grasslands that cover much of the basin also have a unique biodiversity, adapted to the climate and soil conditions of the region. These ecosystems play a role in water infiltration into the soil and in reducing surface runoff, although to a lesser extent than riparian forests. The conversion of native fields to monocultures or degraded pastures can alter the water 91 distributed, which consider the spatial variability of the basin's characteristics. The main benefits of hydrological modelling for flood forecasting include: ● Early Forecasting: Models can simulate the river's response to predicted rainfall, providing alerts hours or days in advance, depending on the scale of the basin and the availability of meteorological data. This is crucial so that civil defence and the population have enough time to prepare. ● Scenario Analysis: Models allow different rainfall scenarios (e.g., rainfall of different intensities and durations) to be tested and their potential impacts on river levels to be assessed. This helps to identify the most critical scenarios and plan appropriate responses. ● Identification of Risk Areas: Hydraulic models, which simulate water flow in rivers and floodplains, can identify the areas most susceptible to flooding and the expected water depth. This information is vital for risk zoning and urban planning. ● Evaluation of Mitigation Measures: They can be used to evaluate the effectiveness of different mitigation measures, such as the construction of dams, dykes, or the restoration of riparian forests, before their implementation. This allows for the optimisation of investment in infrastructure and nature-based solutions. 92 ● Better Understanding of Processes: The process of building and calibrating a hydrological model deepens knowledge about the basin's hydrological processes, identifying the most influential factors and the interactions between them. For a hydrological model to be effective, it requires high-quality input data, including precipitation data, topography (digital elevation model), land use and occupation, and soil characteristics. Model calibration, which involves adjusting its parameters so that it accurately reproduces the observed behaviour of the river, is a critical step. Validation, which tests the model with independent data, ensures its reliability. In the context of the Uruguay River basin, integrating data from ANA stations with advanced hydrological models can create a more robust and accurate flood forecasting system. This would not only allow for predicting water level rises, but also for estimating the area and depth of flooding, providing more detailed information for emergency management and long-term planning. Investment in hydrological modelling is therefore a fundamental step towards improving Uruguaiana's resilience to flooding. 7. Details of the 2024 Flood Events For a more in-depth analysis of the results, it is essential to detail the three significant flood events that occurred in 2024, as identified in the overview of the data. Each of these events has 93 distinct characteristics that contribute to understanding the complex hydrological dynamics of the Uruguay River in Uruguaiana. 7.1. June 2024 Flood: The First Alert of the Year The second quarter of 2024 marked the first notable flood event. In June 2024, the water level of the Uruguay River in Uruguaiana reached a significant peak. This event was driven by considerable rainfall in the upstream stations, especially in Itaqui and São Borja, which recorded above-average precipitation for the period. Analysis of the time lag revealed that the rise in water levels in Uruguaiana occurred approximately 2 to 3 days after the rainfall peaks in these locations. This relatively short response time highlights how quickly the river reacts to rainfall in its upper basin. Although local rainfall in Uruguaiana in June 2024 was not exceptionally high, soil saturation due to previous rains and the continuous inflow of water from upstream areas were determining factors in the magnitude of this flood. This event served as a first warning for the year, demonstrating the city's vulnerability and the need for constant monitoring . The consequences included minor flooding in lower riverside areas and the need to relocate some families, highlighting the importance of early warning systems to mitigate impacts. 94 7.2. September 2024 Flood: The Persistence of Water The third quarter of 2024 was characterised by a second flood event, with the river reaching a new peak in September 2024. Unlike the June event, this flood was marked by persistent rainfall throughout the basin, including Garruchos, São Borja, and Itaqui. The accumulated rainfall volumes throughout August and September were substantial, keeping the soil saturated and contributing to continuous surface runoff. Detailed analysis showed that the contribution from Garruchos, although further away, was fundamental to the total volume of water that reached Uruguaiana. The time lag for Garruchos was slightly longer (3 to 4 days), but its cumulative contribution, added to that of São Borja and Itaqui, resulted in a prolonged rise in the river level. This event demonstrated that not only rainfall peaks, but also the duration and spatial distribution of precipitation throughout the basin, are crucial for the formation of floods. The impacts of this flood were more widespread, affecting urban and rural areas and requiring a more coordinated response from civil defence and local authorities. 7.3. November 2024 Flood: The Most Significant Peak The fourth quarter of 2024 saw the third and most significant flood event of the year, with the Uruguay River in Uruguaiana reaching its highest level in November 2024. This peak was the result of intense and concentrated rainfall in all seasons upstream, especially in Itaqui and São Borja, which recorded 95 exceptionally high rainfall volumes. The combination of high intensity and wide spatial distribution of rainfall created a scenario of large-scale flooding. The correlation between rainfall volumes and elevation was more evident during this period, reinforcing the study's central hypothesis. The response time was consistent with previous events, allowing early warning systems to function, although the magnitude of the flooding exceeded expectations in some areas. The impacts were severe, with extensive flooding, displacement of a large number of families, significant damage to agriculture and livestock, and disruption of essential services. This November 2024 event serves as a clear example of the need for continuous monitoring and robust risk management strategies to deal with extreme events in the Uruguay River basin. In summary, the 2024 flood events in Uruguaiana demonstrated the complexity of the hydrological dynamics of the Uruguay River and the interconnection of the entire basin. Detailed analysis of each flood peak, considering upstream rainfall conditions and time lag, is essential to improve the ability to predict and respond to future events, ensuring the safety and resilience of riverside communities. 8. Trend and Seasonality Analysis In addition to analysing specific flood events, understanding the trends and seasonality of rainfall and water level data is essential for a comprehensive view of the hydrological regime of the 96 Uruguay River in Uruguaiana. Identifying recurring patterns throughout the year and observing long-term trends can assist in water resource planning and management. 8.1. Rainfall Seasonality The Uruguay River basin, like much of southern Brazil, has a well-defined rainfall seasonality. Generally, the spring and summer months (October to March) are characterised by higher rainfall volumes, often associated with convective systems and cold fronts advancing over the region. These months tend to have the highest precipitation volumes, which in turn contributes to rising river levels. In contrast, the autumn and winter months (April to September) tend to have lower rainfall volumes, although isolated events of intense precipitation may occur. However, analysis of data from 2024 revealed that even in periods of lower average rainfall, the occurrence of rainfall concentrated in short periods or the persistence of rainy systems can generate significant flooding, as observed in June and September. This indicates that seasonality, although a guide, is not the only factor to be considered; the intensity and temporal distribution of rainfall are equally important. 8.2. Seasonality of River Levels 97 The seasonality of the Uruguay River levels in Uruguaiana largely follows the seasonality of rainfall in the basin. River levels tend to be higher in the months with the highest precipitation and decrease during dry periods. However, the time lag between rainfall and the river's response means that peak water levels may occur with a delay in relation to peak precipitation. It has been observed that, after the months of lowest water levels (such as March 2025, with 171.79 m), the river begins to recover with increased rainfall, culminating in flood peaks. This dynamic of rise and fall in river levels is a natural cycle, but it can be intensified by factors such as climate change and changes in land use in the basin. 8.3. Long-Term Trends Although the period analysed in this study is limited to one year, the analysis of long-term trends is crucial to understanding changes in the hydrological regime of the Uruguay River. Climatological and hydrological studies for southern Brazil have pointed to a trend of increasing frequency and intensity of extreme precipitation events. This means that, in the future, floods may become more frequent and more severe, and periods of drought more prolonged. This trend towards more intense extreme events is largely attributed to global climate change. The increase in the planet's 98 average temperature leads to greater evaporation of water from oceans and water bodies, resulting in an atmosphere with a greater capacity to retain moisture. When this moisture condenses, it can generate more intense and concentrated rainfall. In addition, phenomena such as El Niño and La Niña, which influence rainfall patterns in South America, may have their frequency and intensity altered by climate change, directly impacting the Uruguay River basin. The analysis of long-term trends requires the use of historical data series spanning several decades, which was not the main focus of this study. However, awareness of these trends is essential for long-term planning and the implementation of adaptation and mitigation measures aimed at increasing the resilience of the city of Uruguaiana and riverside communities. This includes investments in drainage infrastructure, protection of floodplain areas, restoration of riparian forests, and the development of more robust early warning systems adapted to a scenario of more frequent extreme events. In short, the analysis of trends and seasonality in rainfall and water level data provides an important context for understanding flood events. The Uruguay River basin has clear seasonality, but long-term trends, influenced by climate change, indicate the need for proactive and adaptive planning to address future challenges posed by the river's hydrological regime. 99 9. The Role of Dams and Reservoirs in Flood Regulation The Uruguay River basin, like other large Brazilian basins, has a series of dams and reservoirs along its main course and various tributaries for multiple uses, such as power generation, water supply, and flood control (ANA, 2019; BRAZIL, 2016). The operation of these structures directly interferes with the hydrological dynamics downstream, influencing the behaviour of floods in vulnerable areas, such as Uruguaiana. Understanding the role of these projects is essential for the integrated and efficient management of the basin's water resources (MANTOVANI et al., 2021). When operated with a focus on flow regulation, dams can act as natural buffers, retaining a significant portion of the excess volume during episodes of intense precipitation and thus attenuating the peak flow downstream (TUCCI, 2008; BARROS et al., 2020). This function is especially relevant in concentrated rainfall events, in which surface runoff tends to be rapid and intense. However, managing these structures is challenging, given that multiple operational objectives—especially energy production— can compete with the flood control function. Maintaining high reservoir levels to maximise energy generation, for example, can reduce the capacity to absorb additional volumes during critical periods (RIBEIRO, 2015). In addition, uncoordinated water releases, especially in sync with local precipitation peaks, can intensify downstream impacts (DEFESA CIVIL RS, 2023). 100 , integration between plant operators, management bodies such as the National Water and Basic Sanitation Agency (ANA), and state and municipal civil defence agencies is therefore essential. The exchange of real-time data on reservoir levels, flows, and weather forecasts allows for more responsive and strategic operation, reducing the risks associated with flooding (ANA, 2022; MOTA et al., 2019). In this context, operating plans that incorporate water safety criteria and clear water release protocols are indispensable. Transparency in the management and communication process is equally important. Riverside populations must have access to clear and up-to-date information on reservoir levels and forecast scenarios in order to prepare adequately. Civil society participation in basin committees and decision-making processes strengthens governance and contributes to the development of more equitable and sustainable solutions (MARANDOLA JR. & HOGAN, 2014; ANA, 2021). In summary, dams and reservoirs are strategic tools for flood mitigation in the Uruguay River basin. However, their effectiveness depends on coordinated, transparent operation guided by the protection of the downstream population. Integrating these projects into early warning systems and contingency plans is essential to increase resilience to extreme hydrological events. 10. The Impact of Urbanisation and Land Use on Flood Dynamics 107 Political challenges can arise from a lack of political will, the discontinuity of projects due to management changes, and pressure for short-term solutions at the expense of long-term strategies. Flood management often involves unpopular decisions, such as restricting occupation in risk areas or relocating families, which can generate political and social resistance. The perception that prevention is less visible than disaster response can also divert focus and resources to emergency actions. Finally, social challenges include a lack of public awareness of the risks, resistance to changing habits, and mistrust of government actions. The irregular occupation of risk areas, often ly by low-income populations who have no other housing options, is a complex social problem that requires integrated solutions combining urban planning, housing policies, and social assistance programmes. Environmental education and community engagement are essential to overcoming these challenges and building a culture of prevention and resilience. Overcoming these challenges requires a joint and coordinated effort by all stakeholders. Policy integration, institutional strengthening, continued investment in research and technology, professional training, and the promotion of social participation are essential steps to make flood management policies more effective and contribute to the safety and well-being of communities along the Uruguay River. 108 13. Impacts on Public Health and the Environment In addition to the direct impacts on the population, agriculture, and infrastructure, flooding of the Uruguay River in Uruguaiana also has significant consequences for public health and the environment. These impacts, often long-term, require attention and specific strategies for mitigation and prevention. In terms of public health, flooding creates an environment conducive to the spread of disease. The contamination of drinking water by sewage and debris, the accumulation of waste and the presence of venomous animals and disease vectors (such as mosquitoes and rodents) increase the risk of outbreaks of infectious diseases such as leptospirosis, diarrhoea, hepatitis A and dengue fever. The disruption of basic sanitation services, such as treated water supply and sewage collection, further aggravates the situation. In addition, post-traumatic stress, anxiety, and depression are common mental health problems among affected populations, requiring psychosocial support and accessible mental health services. The environmental impacts of flooding are also considerable. Soil and riverbank erosion, silting of watercourses, and contamination by solid and liquid waste are recurring problems. Flooding of agricultural areas can lead to the leaching of pesticides and fertilisers into rivers, compromising water quality and affecting aquatic biodiversity. The destruction of riparian forests and other riverside ecosystems, which act as natural filters and protective barriers, increases the vulnerability of the 109 basin to future extreme events. The recovery of these ecosystems is a slow and complex process that requires investment and environmental restoration actions. Another important aspect is the improper disposal of waste during and after floods. The volume of rubbish and debris generated by floods is immense, and its incorrect disposal can contaminate the soil and water, as well as create sources of disease. Waste management in emergency situations is a logistical and environmental challenge that needs to be planned and executed efficiently, with the participation of the community and the support of public and private agencies. Floods can also affect local wildlife, displacing animals from their natural habitats and increasing the risk of contact with the human population. The presence of venomous animals, such as snakes and scorpions, in flooded urban areas is an additional concern for people's safety. Protecting wildlife and minimising impacts on biodiversity are important aspects of post-flood environmental management. In short, the impacts of floods on public health and the environment are interlinked and highly complex. Preventing and mitigating these impacts requires an integrated approach that combines health, sanitation, environmental management, and education actions. Investment in sanitation infrastructure, promotion of sustainable agricultural practices, protection and restoration of ecosystems, and raising public awareness of the risks are essential measures for building a healthier and more 110 resilient Uruguaiana in the face of the challenges posed by the flooding of the Uruguay River. 14. Economic Costs of Recovery and Reconstruction The economic costs associated with recovery and reconstruction after flooding events are enormous and represent a significant burden on public and private budgets. y quantification of these costs is essential for long-term planning, resource allocation, and justification of investments in preventive measures. In Uruguaiana, with each flood, the city and its inhabitants face a complex financial equation to rebuild. Direct costs include expenses related to the immediate emergency response, such as mobilising rescue teams and providing temporary shelters, food, water, and medicine to victims. The reconstruction of homes, the repair of damaged infrastructure (roads, bridges, power and sanitation networks) and the cleaning of affected areas also represent considerable direct expenses. For agriculture and livestock, direct costs involve replacing lost crops and herds, recovering soil and rebuilding rural facilities. Indirect costs are more difficult to quantify, but equally significant. They include the loss of economic productivity due to the interruption of commercial and industrial activities, the decline in tourism, job losses, and reduced tax revenues. The impact on public health, with an increase in disease and the need for treatment, also generates indirect costs for the health system. 111 In addition, the social and psychological cost to affected families, although intangible, has a profound impact on the quality of life and resilience of the community. Long-term recovery requires investments in more resilient infrastructure, such as improved drainage systems, dykes and dams, and the restoration of natural ecosystems. These investments, although expensive, are crucial to reducing vulnerability to future events and avoiding even greater costs in the future. A cost-benefit analysis of preventive measures versus recovery costs shows that investing in prevention is, in the long run, the most economical and sustainable option. Financing recovery is a complex challenge. Municipalities often depend on federal and state resources, which can be slow to release and are not always sufficient to cover all needs. The lack of flood insurance for most properties and economic activities exacerbates the situation, leaving families and businesses unprotected. Creating disaster funds, promoting affordable insurance, and seeking international sources of financing can be strategies to ensure the availability of resources for recovery. In addition to the financial costs, there is the opportunity cost. The resources that are diverted to disaster recovery could be invested in other areas, such as education, health, or economic development, which could generate long-term benefits for the community. This reinforces the importance of prioritising risk prevention and mitigation, transforming disaster costs into investments in resilience. 112 In conclusion, the economic costs of recovery and reconstruction after floods are multifaceted and represent a heavy burden for Uruguaiana. Understanding these costs, both direct and indirect, is essential for the development of public policies that prioritise prevention, investment in resilient infrastructure and the creation of financing mechanisms that ensure the city's resilience in the face of the challenges posed by the Uruguay River. 15. Ecosystem-Based Adaptation (EBA) as a Strategy for the Future In the face of growing uncertainties and challenges posed by climate change, Ecosystem-based Adaptation (EbA) emerges as a promising and cost-effective strategy for flood management and resilience building in river basins such as the Uruguay River. EBA involves the use of biodiversity and ecosystem services as part of an overall adaptation strategy to help people adapt to the adverse impacts of climate change. Rather than relying solely on traditional engineering solutions (such as dykes and dams), EoB integrates nature-based solutions that offer multiple benefits. The main principles of NBS include: ● Ecosystem Restoration: Restoring riparian forests, wetlands, and other riverine ecosystems is one of the key strategies of AbE. These ecosystems act as natural sponges, 113 absorbing excess water during floods, reducing surface runoff velocity, and filtering sediments and pollutants. Restoring these ecosystems not only helps mitigate flooding, but also improves water quality, increases biodiversity, and sequesters carbon. ● Sustainable Soil Management: Promoting sustainable agricultural practices, such as no-till farming, crop rotation, and crop-livestock-forest integration, contributes to soil health and reduces surface runoff. Healthy soils have greater water infiltration and retention capacity, which helps to reduce the volume of water reaching rivers during rainfall. ● Green Infrastructure: The implementation of green infrastructure in urban areas, such as floodable parks, green roofs, rain gardens, and permeable pavements, is another EaB strategy. These solutions help manage rainwater at the source, reducing the overload on drainage systems and the risk of urban flooding. In addition, green infrastructure improves air quality, reduces heat islands, and creates recreational spaces for the community. ● Biodiversity Conservation: Protecting biodiversity and natural habitats is critical to the resilience of ecosystems and the maintenance of the services they provide. The creation of protected areas, ecological corridors, and the implementation of conservation policies are essential to ensuring the long-term health of the basin. 114 The benefits of NBS are manifold and go beyond flood management. They promote water security, food security, biodiversity conservation, and sustainable economic development. In addition, nature-based solutions are often cheaper and more resilient in the long term than traditional engineering solutions. In the context of the Uruguay River basin, the implementation of NBS strategies can be a promising way to address the challenges of climate change and build a more secure and sustainable future. This requires a paradigm shift in the way we plan and manage the territory, integrating nature conservation with social and economic development. Collaboration between governments, the private sector, civil society, and local communities is essential for the success of EoB and for building a more resilient basin for future generations. 16. The Role of International Cooperation in Transboundary Basin Management The Uruguay River basin, like other large Brazilian basins, has a series of dams and reservoirs along its main course and various tributaries for multiple uses, such as power generation, water supply, and flood control (ANA, 2019; BRAZIL, 2016). The operation of these structures directly interferes with the hydrological dynamics downstream, influencing the behaviour of floods in vulnerable areas, such as Uruguaiana. Understanding the role of these projects is essential for the integrated and 115 efficient management of the basin's water resources (MANTOVANI et al., 2021). When operated with a focus on flow regulation, dams can act as natural buffers, retaining a significant portion of the excess volume during episodes of intense precipitation and thus mitigating the peak flow downstream (TUCCI, 2008; BARROS et al., 2020). This function is especially relevant in concentrated rainfall events, in which surface runoff tends to be rapid and intense. However, managing these structures is challenging, given that multiple operational objectives—especially energy production— can compete with the flood control function. Maintaining high reservoir levels to maximise energy generation, for example, can reduce the capacity to absorb additional volumes during critical periods (RIBEIRO, 2015). In addition, uncoordinated water releases, especially in sync with local precipitation peaks, can intensify downstream impacts (DEFESA CIVIL RS, 2023). , integration between plant operators, management bodies such as the National Water and Basic Sanitation Agency (ANA), and state and municipal civil defence agencies is therefore essential. The exchange of real-time data on reservoir levels, flows, and weather forecasts allows for more responsive and strategic operation, reducing the risks associated with flooding (ANA, 2022; MOTA et al., 2019). In this context, operating plans that incorporate water safety criteria and clear water release protocols are indispensable. 116 Transparency in the management and communication process is equally important. Riverside populations must have access to clear and up-to-date information on reservoir levels and forecast scenarios in order to prepare adequately. Civil society participation in basin committees and decision-making processes strengthens governance and contributes to the development of more equitable and sustainable solutions (MARANDOLA JR. & HOGAN, 2014; ANA, 2021). In summary, dams and reservoirs are strategic tools for flood mitigation in the Uruguay River basin. However, their effectiveness depends on coordinated, transparent operation guided by the protection of the downstream population. Integrating these projects into early warning systems and contingency plans is essential to increase resilience to extreme hydrological events. 17. The Importance of Education and Awareness for Resilience Education and awareness-raising among the population are strategic pillars in building resilience to the hydrological risks associated with flooding of the Uruguay River. More than just having warning systems and protective infrastructure in place, it is essential that the local community be informed, mobilised, and prepared to act autonomously and safely in emergency situations (RIBEIRO, 2015; MARANDOLA JR. & HOGAN, 2014). 123 holistic approach can lead to fragmented and ineffective solutions that transfer problems rather than solve them. The dynamics of flooding in Uruguaiana are a testament to this interconnection. As demonstrated in this book, rainfall in municipalities hundreds of kilometres upstream, such as Garruchos, São Borja and Itaqui, directly influences the river level in Uruguaiana. This means that water management, land use and agricultural practices in one part of the basin directly affect communities downstream. For example, deforestation of riparian forests in upper areas of the basin can increase surface runoff and erosion, contributing to river siltation and intensified flooding in Uruguaiana. Integrated river basin management involves coordination between different levels of government (federal, state, municipal), various water user sectors (agriculture, industry, sanitation, energy), civil society, and research institutions. This approach seeks to reconcile the multiple uses of water, protect aquatic and terrestrial ecosystems, and manage the risks of extreme events such as floods and droughts. The creation of river basin committees, which bring together representatives of all these actors, is a fundamental tool for promoting this participatory and integrated management. In the transboundary context of the Uruguay River basin, international cooperation is equally crucial. Agreements and collaboration mechanisms between Brazil, Argentina, and Uruguay are essential for sharing hydrometeorological data, 124 coordinating dam operations, developing joint early warning systems, and implementing risk management projects. Lack of coordination between countries can compromise the effectiveness of disaster prevention and response measures, especially in large-scale events that affect the entire basin. In short, the interconnection of the Uruguay River basin requires a paradigm shift in the way water resources are managed . Fragmented and sectoral management is no longer sustainable in the face of the challenges posed by climate change and increasing pressure on water resources. Adopting an integrated approach, which considers the basin as a single system and promotes collaboration among all actors, is the way to ensure water security, environmental protection, and sustainable development for the communities along the Uruguay River. 125 Chapter 5 - Practical Actions for the Community and Individuals Ana Helena de Souza Sigaran1 Suelen Potira Chaves Yosuf1 Jocemar Antonio Toso1,2 Diogo Ricardo Martins Balestra3 Cassiane Jrayj de Melo4 1 Student in the Aquaculture Engineering Course, UNIPAMPA; 2 Aquaculture Technologist, UNIPAMPA; 3 Administrator, Law Student, Postgraduate in Environmental Law and MSc in International Business, Must University; (4) Agricultural Engineer, MSc Geography: Remote Sensing; PhD Soil Science, UFSM. 1. Introduction Although public policies and investments in infrastructure play a central role in disaster mitigation, it is at the local level that a significant part of flood resilience is consolidated. The actions of the community and individuals are essential to complement institutional strategies and strengthen response and recovery capacity in the face of extreme events (RIBEIRO, 2015; MARANDOLA JR. & HOGAN, 2014). Awareness and preparedness at the family and community level constitute the first line of defence against the impacts of flooding, promoting a culture of self-protection and vulnerability reduction (BRAZIL, 2016; DEFESA CIVIL RS, 2023). One of the most important actions is to develop a family emergency plan. This plan should include: ● Evacuation Routes: Identify the safest routes to leave your home and neighbourhood in case of flooding, and practise them regularly. 126 ● Meeting Points: Define a safe place outside the risk area where the family can meet if they become separated during the evacuation. ● Emergency Kit: Prepare a backpack with essential items such as drinking water, non-perishable food, medicines, a torch, a battery-powered radio, important documents (in waterproof plastic bags), a first aid kit, clothing and personal hygiene items. This kit should be easily accessible and reviewed periodically. ● Emergency Contacts: Have a list of useful telephone numbers, including civil defence, fire brigade, hospitals and contacts for family and friends. ● Pet Care: Include pets in your evacuation plan, ensuring that they also have a safe place and supplies. Another key action is to protect your belongings and documents. In areas at risk, it is advisable to raise furniture and appliances, if possible, and store important documents in high, waterproof locations. Scanning documents and storing them in the cloud are also effective preventive measures. Participation in education and simulation programmes promoted by civil defence or other organisations is highly recommended. These programmes offer valuable information and practical training that can make a difference in an emergency situation. Knowledge of warning signs, such as rising river levels or forecasts of heavy rain, allows people to make informed decisions and act in advance. 127 Maintaining homes and land also contributes to risk reduction. Cleaning gutters and drains, avoiding littering in streams and rivers, and maintaining vegetation in riparian areas can help improve water runoff and reduce the risk of localised flooding. In rural areas, adopting sustainable agricultural practices that minimise soil erosion and promote water infiltration is equally important. Finally, solidarity and mutual aid are essential in times of crisis. Getting to know neighbours, especially the elderly or people with reduced mobility, and offering help when needed strengthens community ties and improves collective response capacity. Creating local support networks can make a difference in postflood recovery. By adopting these practical actions, individuals and communities can significantly increase their resilience to flooding, minimising impacts and speeding up the recovery process. Prevention is an ongoing effort that requires everyone's participation. 2. The Role of Civil Society and Non-Governmental Organisations (NGOs) Organised civil society and non-governmental organisations (NGOs) play an essential role that complements government actions in flood management and the promotion of community resilience. Their decentralised action, which is closer to vulnerable populations, allows them to fill institutional gaps, 128 increasing the effectiveness of disaster prevention, response and recovery strategies (RIBEIRO, 2015; BRAZIL, 2016). One of the main contributions of NGOs lies in social mobilisation and community empowerment. Workshops, training courses, educational campaigns and family emergency plans help to strengthen community organisation and the autonomy of populations exposed to hydrological risks (MARANDOLA JR. & HOGAN, 2014). The creation of emergency brigades and the training of local leaders are examples of actions made possible by these institutions, adapted to specific socio-territorial realities (ANA, 2019). NGOs also collect, analyse and disseminate information. In many cases, they carry out local monitoring of rivers and precipitation, complementing data from official networks. In addition, they function as important vectors of communication between public authorities and communities, translating technical alerts into accessible language and using informal channels such as social networks, community radio stations and instant messaging groups (DEFESA CIVIL RS, 2023). In crisis situations, verifying information and combating misinformation are crucial functions in preventing panic or negligence in the face of risk. During disaster response, NGOs often position themselves as the first entities to offer emergency assistance. The distribution of food, drinking water, hygiene items, clothing, temporary shelter, and psychosocial support are routine activities carried out with agility and a focus on the immediate needs of the affected populations (BARROS et al., 2020). 129 In the post-disaster period, these organisations also collaborate in the reconstruction of housing, economic rehabilitation, and the resumption of community life, including prolonged psychological support. Additionally, they play a fundamental role in defending the rights of victims, ensuring their participation in decisionmaking processes and access to aid provided by the state (MOTA et al., 2019). NGOs also act strategically in political advocacy, demanding greater transparency, social participation, and investment in public policies aimed at disaster prevention and the sustainable use of water resources from governments (IPCC, 2021; ANA, 2021). By documenting impacts, collecting data and raising awareness of the demands of affected populations, these organisations broaden the scope of the socio-environmental agenda and push for structural changes in land and water management. In short, NGOs and civil society collectives are indispensable actors in building a Uruguaiana that is more resilient to flooding. Their capacity for mobilisation, their local action and their technical and social expertise qualify them as strategic partners for more democratic, inclusive and effective risk management. The institutional strengthening of these organisations and the formal recognition of their role should be priorities for the governance of the Uruguay River basin. 3. The Challenge of Financial Sustainability in Flood Management 130 Flood management, in all its phases – prevention, mitigation, response and recovery – requires significant and continuous financial investment. However, the financial sustainability of these actions is a persistent challenge, especially in developing countries and municipalities with limited budgets. The absence of a stable and predictable flow of resources can compromise the effectiveness of policies and the ability to respond to extreme events. Overcoming this challenge requires the search for diversified sources of financing and the implementation of innovative financial mechanisms. One of the main sources of funding for flood management is public budgets (federal, state, and municipal). However, these budgets are often limited and subject to economic fluctuations and political priorities. The allocation of resources for disaster prevention and mitigation often competes with other urgent demands, such as health, education, and security, which can lead to underinvestment in long-term preventive measures. The creation of specific funds for disaster risk management, with dedicated and protected sources of revenue, can ensure the necessary financial stability. The private sector can also play an important role in financing flood management. Companies operating in risk areas or dependent on the basin's water resources can be encouraged to invest in prevention and mitigation measures, such as the construction of protective infrastructure, the restoration of ecosystems, and the implementation of sustainable practices. Mechanisms such as payment for environmental services (PES), 131 where water users compensate landowners who conserve water recharge areas or riparian forests, can generate resources for basin management. The insurance market is another financial tool that can contribute to resilience. Promoting flood insurance, both for properties and economic activities, can help distribute risk and ensure the financial recovery of victims. However, the low penetration of such insurance, especially in areas of greater vulnerability, is a challenge. Public policies that encourage the purchase of insurance, such as subsidies or awareness programmes, can increase uptake. In addition, seeking international financing is an important strategy, especially for large-scale projects or for countries with lower investment capacity. Development banks, international cooperation agencies, and climate funds offer credit lines and grants for climate change adaptation and disaster risk reduction projects. The ability to develop well-structured projects and demonstrate socio-economic and environmental benefits is crucial to attracting these resources. Cost-benefit analysis is an essential tool for justifying investments in prevention. Studies have shown that every dollar invested in prevention can save multiple dollars in recovery and reconstruction costs. However, quantifying these benefits, especially intangible ones (such as lives saved and reduced human suffering), is challenging. Effective communication of 132 these benefits to decision-makers and society is key to securing support for investments in prevention. Finally, innovation in financial mechanisms is crucial. This includes the creation of green bonds, impact investment funds, and public-private partnerships that can leverage resources for flood management. Combining different sources of financing and creating sustainable financial models are essential to ensure that communities and th s of the Uruguay River basin are prepared to face the future challenges posed by flooding. 4. The Role of Governance and Transparency in Flood Management Governance and transparency are fundamental pillars for the effectiveness, legitimacy, and sustainability of flood management. Effective governance requires consolidated institutions, well-defined regulatory frameworks, participatory decision-making processes, and clear mechanisms for accountability and social control (BRAZIL, 2016; MARANDOLA JR. & HOGAN, 2014). Transparency, in turn, ensures public access to information on dam operations, contingency plans and warning systems, strengthening trust between government and society and encouraging community engagement in prevention and response actions (ANA, 2019; RIBEIRO, 2015). The absence of these elements compromises the efficiency of actions, opens the door to inappropriate management practices, 139 facilitate access to and use of hydrometeorological information by different actors. Research on infrastructure resilience and the development of more flood-resistant construction materials and techniques are also areas of great relevance. In addition to technology, social and economic research is essential to understanding the impacts of flooding on communities and to developing adaptation strategies that are socially just and economically viable. This includes studies on social vulnerability, risk perception, the effectiveness of public policies, and the economic costs of disasters. In short, scientific research and innovation are essential drivers for improving flood management in Uruguaiana and the Uruguay River basin. Continued investment in science and technology, the promotion of collaboration between universities, research centres, governments and the private sector, and the application of the knowledge generated in practice are fundamental steps towards building a safer and more resilient future for riverside communities. 7. The Importance of Watershed Management for Flood Prevention Watershed management is a fundamental concept for understanding and managing water resources, especially with regard to flood prevention and mitigation. A watershed, by its very definition, is a territorial unit where all precipitation water converges to a single outlet point, be it a river, lake or ocean. 140 This natural interconnection means that actions and events in any part of the watershed can have significant impacts on others, highlighting the need for an integrated and holistic approach. In the context of the Uruguay River and the floods in Uruguaiana, watershed management transcends municipal and state boundaries, reaching an international dimension, since the river is shared by Brazil, Argentina, and Uruguay. This complexity requires multi-level and multi-institutional coordination for flood prevention strategies to be effective. One of the pillars of river basin management is land use and occupation planning. The way in which land is used and occupied throughout the basin directly influences the hydrological regime. Deforestation, the expansion of urban areas without adequate planning, and the occupation of floodplains and floodd plains reduce the natural capacity of the soil to absorb and retain water, increasing surface runoff and the speed at which water reaches rivers. This, in turn, intensifies flood peaks and reduces response time for downstream communities. The implementation of ecological-economic zoning and master plans that consider the water dynamics of the basin is crucial for sustainable development and risk reduction. The conservation and restoration of natural ecosystems are equally important. Riparian forests, wetlands, and springs act as natural infrastructures that regulate water flow, filter pollutants, and protect the soil from erosion. Restoring these degraded areas through reforestation and environmental recovery 141 programmes can increase the basin's resilience, helping to reduce the magnitude and frequency of floods. These naturebased solutions are often more cost-effective and sustainable in the long term than large engineering works. Water resource management, which includes the operation of dams and reservoirs, should also be integrated into basin management. Coordination between hydroelectric plant operators and flood management agencies is essential to optimise water release, ensuring power generation while minimising the impacts of downstream flooding. Transparent communication and real-time data sharing are essential for this coordination. In addition, social participation is a key component of river basin management. The creation of basin committees, which bring together representatives from governments, water users, civil society, and research institutions, allows decisions to be made in a participatory manner and different interests to be reconciled. Community engagement in the development of management plans, oversight, and implementation of actions is critical to the success of initiatives. In summary, river basin management is a strategic and integrated approach that recognises the interconnection of natural and human systems. By considering the basin as a planning and management unit, it is possible to develop more effective strategies for flood prevention, water resource conservation and the promotion of sustainable development. For 142 the Uruguay and Uruguaiana rivers, this approach is imperative for building a safer and more resilient future in the face of the challenges posed by climate change and increasing pressure on natural resources. 8. The Role of Environmental Education in Building Resilience Environmental education is a fundamental pillar in building the resilience of communities in the face of natural disasters, such as the flooding of the Uruguay River in Uruguaiana. More than simply transmitting information, environmental education seeks to promote a change in values, attitudes, and behaviours, empowering individuals and communities to understand the complex relationships between the environment and society and to act responsibly and proactively in risk management. In the context of flooding, environmental education plays several crucial roles: ● Risk Awareness: Often, the population is not fully aware of the risks to which it is exposed, especially in historically occupied floodplain areas. Environmental education can inform people about river dynamics, the factors that contribute to flooding (natural and anthropogenic), and the potential impacts on life and property. This awareness is the first step towards adopting preventive measures. 143 ● Understanding the Watershed: It is essential that people understand that they live in a watershed and that actions taken in one part of the watershed can affect others. Environmental education can illustrate the interconnection between upstream rainfall and downstream flooding, showing how deforestation, soil sealing, and pollution in distant areas can impact the local community. This systemic view is fundamental to promoting integrated management. ● Promoting Safe Behaviour: Environmental education can teach the population how to act before, during, and after a flood. This includes developing family emergency plans, preparing survival kits, identifying safe evacuation routes, and the importance of following civil defence guidelines. Conducting simulations and practical training can reinforce these behaviours and increase response capacity in emergency situations. ● Encouraging Sustainable Practices: Environmental education can promote the adoption of more sustainable practices in everyday life, which contribute to reducing flood risks. This includes proper waste disposal, water conservation, planting trees in degraded areas, and supporting public policies aimed at protecting riparian forests and proper land use management. Small individual actions, when multiplied, can have a significant impact on the resilience of the basin. ● Strengthening Citizen Participation: Environmental education can empower communities to actively participate in decision-making processes related to water resource 144 management and disaster prevention. By understanding their rights and responsibilities, citizens can monitor government actions, propose solutions, and defend their interests, contributing to more democratic and transparent governance. In Uruguaiana, the implementation of ongoing environmental education programmes adapted to the local reality is a strategic investment. Schools, residents' associations, NGOs and public agencies can work together to disseminate knowledge and promote awareness. By empowering the population with information and skills, environmental education contributes directly to building a culture of prevention and increasing the city's resilience to the challenges posed by the flooding of the Uruguay River. 9. Challenges and Opportunities for Sustainable Development in the Uruguay River Basin The Uruguay River basin, with its vast expanse and natural wealth, presents a complex scenario of challenges and opportunities for sustainable development. The search for a balance between economic growth, social inclusion, and environmental protection is imperative to ensure the prosperity of riverside communities and the long-term health of the ecosystem. Flooding, although a natural phenomenon, intensifies the urgency of addressing these challenges in an integrated manner. 145 One of the main challenges is the pressure on natural resources. The expansion of agriculture and livestock farming, the demand for energy and increasing urbanisation exert significant pressure on soil, water and biodiversity. e deforestation, soil erosion, water pollution from pesticides and sewage, and the loss of natural habitats are direct consequences of this pressure. The lack of adequate planning and enforcement exacerbates these problems, compromising the basin's ability to provide essential ecosystem services, such as regulating the water cycle and purifying the air. Climate change represents a cross-cutting challenge that amplifies the others. The increased frequency and intensity of extreme events, such as prolonged droughts and torrential rains, directly impact water availability, agricultural productivity, and community safety. Uncertainty about future scenarios requires flexible and robust adaptation strategies that consider climate variability and associated risks. However, the Uruguay River basin also offers significant opportunities for sustainable development. Sustainable agriculture and livestock farming, for example, can be promoted through conservationist practices such as no-till farming, crop-livestock-forest integration, and organic farming. These practices not only reduce environmental impact but can also increase productivity and the resilience of production systems to climate variations. 146 Ecological and cultural tourism is another opportunity to be explored. The scenic beauty of the Uruguay River, its beaches, islands, and the rich biodiversity of the region, combined with the local culture and history of the riverside communities, can attract visitors and generate income for the population. The development of tourist itineraries that value nature and local culture, with a focus on sustainability and community involvement, can be a driver of diversified economic development. The generation of renewable energy, in addition to hydroelectric power, also has potential. The basin has resources for solar and wind power generation, which can complement the energy matrix and reduce dependence on non-renewable sources. Investment in clean and efficient technologies is essential for sustainable energy development. Integrated solid waste management and basic sanitation are challenges that, once overcome, become great opportunities for public and environmental health. Sewage treatment, selective collection and waste recycling not only improve the quality of life of communities, but can also generate jobs and income, in addition to protecting the basin's water resources. Finally, cross-border cooperation between Brazil, Argentina, and Uruguay is a unique opportunity for the sustainable development of the basin. The exchange of knowledge, coordination of policies, and implementation of joint projects can strengthen the capacity of all countries to address common 147 challenges and promote more equitable and sustainable regional development. The Uruguay River l basin is therefore a living laboratory where sustainability challenges meet opportunities for innovation and collaboration, requiring a long-term vision and a collective commitment to building a more resilient and prosperous future. 10. The Role of Media and Communication in Raising Awareness about Floods The media and communication play a crucial role in raising public awareness about floods and promoting a culture of prevention and resilience. In a scenario of increasingly frequent extreme weather events, the way information is conveyed and perceived by the population can directly influence the capacity to respond and adopt preventive measures. Effective communication is therefore a strategic tool in disaster risk management. During a flood event, the media (television, radio, newspapers, internet) is the main source of information for the population. News coverage should be accurate, impartial and timely, providing up-to-date data on river levels, affected areas, evacuation routes and shelter locations. The language used should be clear and accessible, avoiding technical jargon that could confuse the public. Broadcasting stories of resilience and examples of solidarity can also inspire the community and strengthen social ties. 148 In addition to real-time coverage, the media plays a key role in education and prevention. Educational programmes, documentaries, and special reports can address topics such as river dynamics, the impacts of climate change, the importance of environmental preservation, and safety measures to be taken in the event of flooding. Awareness campaigns, in partnership with civil defence agencies and research institutions, can reinforce important messages and encourage the population to prepare. Social media and digital platforms have emerged as powerful tools for communication in emergency situations. They allow for the rapid dissemination of information, interaction with the population, and the mobilisation of volunteers. However, they also pose a challenge, as they can be vehicles for the spread of fake news and rumours, which can cause panic and hinder crisis management. Verifying information and promoting reliable sources are essential in this digital environment. Public agencies and research institutions also need to improve their communication strategies. The availability of realtime hydrometeorological data, the creation of interactive platforms with risk maps, and the publication of reports and studies in accessible language are measures that can increase transparency and public engagement. Partnerships with journalists and communicators can ensure that technical information is effectively translated for the general public. Finally, risk communication should be continuous and not just reactive. It is important that the population be constantly