Demystifying the Impact of Hydropower on Flood Risk and Food Production

Abstract

Over the past few decades, hydropower energy has emerged as a pillar of global clean energy efforts, providing a reliable, around-the-clock, and renewable source of electricity, essential to achieving low emissions targets. However, its rapid expansion, especially in high-precipitation and mountainous regions of developing countries, has sparked growing concerns about its possible negative roles in exacerbating downstream flood risks and destruction of irrigated farmlands. As global hydropower capacity continues to grow by nearly 2% annually, the need to reconcile its benefits for energy security with its implications for water and food systems has never been more urgent. This dissertation seeks to demystify the global impact of hydropower dams in influencing floods and their mitigation, and agricultural systems, through a series of data-driven studies that leverage satellite observations, large-scale geospatial datasets, and open-source analytical frameworks. The overarching question it seeks to answer is “What has been the global impact of world’s hydropower dams for flood risk mitigation and food production in key regions of the world during the past decades?”The first study applied a fully satellite based reservoir monitoring framework, the Reservoir Assessment Tool (RAT 3.0), to the 2018 Kerala floods, showing how near-full reservoir storage before the monsoon peak amplified downstream flooding in steep, high-rainfall terrain. Building on this regional insight, the second study expanded the analysis to over 100 hydropower dams worldwide, using four decades of satellite data and modeled reservoir states to assess global flood behavior. The findings revealed that while 41.1% of studied sites where likely to protect downstream areas from flood risk, 26.2% of sites were likely to worsen the flood risk, driven by misaligned operations during extreme rainfall and loss of storage due to sedimentation. Recognizing that hydropower’s influence extends beyond flood control and deeply into the realm of food production, the next phase of this research sought to quantify how hydropower dams affect downstream agriculture. However, a critical data gap emerged: the absence of a globally consistent map of irrigation canals that connect reservoirs to croplands. To overcome this barrier, the Global Registry of Agricultural Irrigation Networks (GRAIN) was developed, the first open-access, globally consistent map of irrigation canals. GRAIN maps over 3.8 million kilometers of canals across 95 countries, providing a much-needed foundation for quantifying the global extent of surface-water delivery infrastructure. Building upon this foundation, the final study assesses downstream agricultural responses to hydropower reservoirs in developing regions central to the Asian Green Revolution. It introduces a novel Agricultural Impact Score (AIS) that integrates satellite observations, climate data, reservoir outflows, and irrigation networks to quantify the net impact of hydropower on food production. Results reveal strong heterogeneity, with 86% of dams showing net positive impacts through enhanced productivity and flow regulation, while 13.9% exhibit negative impacts linked to flood-induced losses. Nearly 40% of flood-affected sites show delayed productivity gains, suggesting that dam induced flooding can have beneficial sediment deposition related productivity gains. Agricultural productivity is found to be more strongly coupled with reservoir outflow variability than precipitation alone, highlighting the dominant role of dam operations. Overall, the findings demonstrate that while hydropower dams are largely beneficial for enhancing downstream agricultural productivity, their influence on flood risk is more variable, with the potential to either mitigate or exacerbate extreme events depending on reservoir operations and hydroclimatic conditions. These results underscore the need for adaptive reservoir management strategies to balance energy generation with downstream flood safety and food production. As hydroclimatic extremes intensify and variability increases, integrating data-driven insights into reservoir operations and policy frameworks will be critical to ensuring resilient and sustainable hydropower systems.