Global water footprint assessment of hydropower

摘要

Hydropower is an important renewable energy source, but it can consume a lot of water due to evaporation from the reservoir surface, which may contribute to water scarcity. Previous studies mostly used a gross evaporation approach for water footprint assessment where all the evaporation is attributed to hydropower. They fail to consider both evapotranspiration before the dam construction, which should be deducted from the footprint, and the seasonal storage dynamics of water. These considerations are critical for assessing reservoir impacts on water scarcity using temporally explicit water stress indices. This study seeks to fill this gap: we calculate the water footprints of 1500 hydropower plants which cover 43% of the global annual hydroelectricity generation. Apart from reduced water availability, alterations of the flow regime can also adversely affect ecosystems. Therefore, environmental flow requirements are also analysed.