Reducing Climate Change Induced Flood at the Cost of Hydropower in the Lancang-Mekong River Basin

Hydropower dams are proliferating in the riparian countries of the Lancang-Mekong River Basin (LMRB) driven by the pursuit of renewable electricity and societal resilience to flooding. However, the tradeoffs between hydropower production and flood control are unclear in a changing environment. Here, we use a hydrological variable infiltration capacity model combined with a reservoir module to quantify the relative effects of climate change and reservoir operation on flood and hydropower generation in LMRB. Results show that while climate change would increase flood magnitude and frequency, adaptive reservoir operation can reduce flood magnitude by 5.6%-6.4% and frequency by 17.1%-18.9% at the cost of 9.8%-14.4% of basin-wide hydropower generation. Particularly, upstream reservoirs suffer more hydropower loss (5.4 times) than downstream ones when flood control is prioritized in reservoir regulation. Our findings have implications for integrated water and energy management at the transboundary river basin under climate change. Plain Language Summary Dams and reservoirs provide two important services, i.e., flood control and hydropower generation. In this study, we seek to understand the future tradeoff between these two services provided by reservoir regulation in the transboundary Lancang-Mekong River Basin. Using a modeling based approach, we find that climate change will likely lead to more frequent and larger flood events, but reservoir operation, by regulating water discharges and levels in streams, can effectively reduce flood frequency and magnitude at the expense of hydropower generation. Our results highlight the importance of coordinating water and energy management across countries in this transboundary river basin. Key Points Reservoir can mitigate future flood risk from climate change at the cost of reducing hydropower generation in the Lancang-Mekong River Basin Reservoir regulation can delay the timing when flood risk exceeds the historical baseline by at least 20 years in Laos and Thailand Flood control measures would reduce hydropower at a magnitude of 5.4 times in China than downstream countries