Compounded Effects of Climate Change and Cascade Hydropower Development on the Flood and Sediment Regimes in the Mekong River Basin

Abstract:

There are growing concerns about the global boom in hydropower dam construction that can significantly alter the dynamics of floods and sediment transport. Among the global rivers under aggressive development, the Mekong river is getting particular attention due to its significance as a transboundary river that sustains ecosystem and livelihoods in six countries that share the basin. It has been found the existing dams have exerted profound influence on the flood regime over the basin. Since more dams are planned to be built, there is a need for predicting the Mekong hydrology with a consideration of uncertainties in reservoir operation and climate change. In this study, we predict the future flood dynamics over the Mekong river basin using a hydrodynamic model that simulates the inundation dynamics over natural river-floodplain and manmade reservoirs in an integrated manner. The uncertainties of future climate and hydrology are considered by operating the hydrodynamic model with multiple combinations of climate scenarios, climate models, and hydrological models. We also estimate the potential alterations in sediment delivery caused by dams and climate change in conjunction with the changes in flood dynamics.