Has Hydropower Made the World More Flood-Prone?

Hydropower has emerged as a cornerstone of global renewable energy initiatives, providing a reliable and renewable source of electricity essential to achieving low emissions targets. However, its expansion, especially in high-precipitation and mountainous regions of developing countries, has sparked growing concerns about its role in exacerbating downstream flood risks. This study critically examines the complex relationship between hydropower development and flood risk through the analysis of 107 major hydropower dams in such regions of the world spanning a period of 40 years. While 41.1% of the studied dams were found to exhibit flood mitigating characteristics by buffering against extreme inflows, 26.2% of dams were likely to exacerbate flood risks, primarily due to a steady increase in precipitation rates and sedimentation-induced capacity loss. Hydropower dams in regions with shorter downstream river lengths were found to be more flood-inducing than flood-protecting. While regions with flood-protecting dams naturally trigger urbanization and economic growth due to perceived safety and stable energy availability, these benefits are accompanied by the cost of increased deforestation. The study identified hotspots in South America and South Asia, where hydropower dams are more likely to be clustered as flood inducing in nature. Overall, the study calls for a paradigm shift in hydropower planning and management, emphasizing the integration of adaptive flood risk mitigation into energy production strategies keeping in mind the anticipated changes in climate and land cover along with a robust sedimentation management strategy during the dam's service lifespan.