Climate change and extreme events significantly impact water security in river basins worldwide. The increasing frequency and intensity of extreme weather events, such as floods and droughts, threaten the sustainability of water resources, compromising economic development and social well-being. Therefore, it emphasizes the need for water security adaptation measures and resilience in the face of climate change. This thesis presents risk pooling and index-based insurance as viable adaptation measures to increase water security and reinforce the resilience of basins undergoing environmental changes in Brazil.