Global impacts of dams and reservoirs on hydrological droughts

Dams and reservoirs can have a wide range of impacts on local hydrology, for instance affecting soil moisture, water table, vegetation and modifying the frequency, severity and intensity of floods and droughts. In this work, we are quantifying trends in human-modified droughts (frequency, severity and intensity) in the wake of reservoir formation. Drought trends are compared before and after reservoir formation, using paired catchments for control.

 

We perform the analysis on a global level for large reservoirs, using satellite data of surface water changes and a dataset of georeferenced dams to determine the reservoir ages. We also include the impact of smaller reservoirs for a number of chosen case studies around the globe. The overarching goal of this research is to improve our understanding of the human impact on hydrological droughts across the world. Based on our results, we also discuss the potential impact of future dam constructions, particularly in developing countries where such developments are ramping up.