Integrated assessment of climate change impacts on the water-energy-food-ecosystem nexus in multipurpose reservoirs in Brazil

Water security is an increasing challenge globally, especially in regions with resource scarcity and complex management needs. Reservoirs play a critical role in mitigating water crises, but their operation is influenced by climate change and human pressure. Understanding changes in water security indicators (WSI) in basins with reservoirs is crucial for sustainable water management, particularly in semiarid regions. Climate projections from CMIP6 using SSP-RCP scenarios are integrated with Long Short-Term Memory (LSTM) and random forest machine learning techniques to simulate future conditions (2011-2100). This combined approach enables capturing both spatial and temporal variations in water security, identifying critical hotspots and vulnerabilities with enhanced predictive accuracy and robust handling of complex, nonlinear hydrological patterns. These insights inform sustainable water strategies tailored to regional challenges. Building on these outcomes, this study develops an integrated modeling framework to assess climate change impacts on the water-energy-food-ecosystem (WEFE) nexus in multipurpose reservoirs by applying hydrological risk transfer models (HRTM). The framework synthesizes reservoir operation simulations with WSIs and the Brazilian water agency (ANA) framework to analyze multi-sector interactions and risks. It aims to optimize reservoir water releases to meet competing demands while minimizing the risk of water shortages and associated economic impacts, simultaneously maximizing multi-sector water sustainability. A novel aspect is the incorporation of AI techniques into HRTM to dynamically adjust hydrological risk transfer mechanisms, such as reservoir index insurance. These insurance contracts, indexed to measurable reservoir inflows, provide financial protection against droughts and floods, redistributing risks spatially and temporally among water users. The framework accounts for seasonality, compound risks, and regional reservoir interactions, enabling comprehensive risk and resilience assessment. Preliminary analyses identify vulnerability hotspots and economic impacts of climate-driven hydrological changes, supporting adaptive reservoir management and insurance design to enhance sustainability and equity in the WEFE nexus. The integrated socio-hydrological, economic, and climate scenario approach advances reservoir management under climate uncertainty, balancing ecological protection with socio-economic objectives for sustainable water security in Brazil’s semiarid regions.

Keywords: water security, climate change impact, reservoir management, water-energy-food-ecosystem nexus, hydrological risk transfer.