Calculation and analysis of water footprint of hydropower stations in Yalong River Basin

In order to quantify the effect of hydropower development and utilization for local water resources, this paper introduces the concept of water footprint, taking the cascade reservoirs in the Yalong River Basin as the research object, selecting the total water consumption method, using the measured data for many years, and considering three system space boundaries to calculate the water footprint of seven hydropower stations. The results show that the water footprint of the seven hydropower stations in the Yalong River Basin ranges from 0.01 to 2.91 m³/GJ and the average water footprint is 1.13 m³/GJ, which is smaller than other water footprints of global and national spatial scales. It also means that the utilization efficiency of water resources of hydropower development and utilization in the basin is higher than that of other regions and river basins. The water footprint of the hydropower station is mainly affected by the energy efficiency factor (water surface area of the reservoir area per unit installed capacity) and the topographic factor (the water surface area of the reservoir area and the average water depth ratio of the reservoir area), and the correlation indexes are 0.950 7 and 0.783 1, respectively. However, the evaporation depth and meteorological factors (rainfall and temperature) have less impact on the water footprint of hydropower stations. The water footprint of the hydropower station is related to the setting of the boundary of the space system. It is necessary to select the appropriate space system boundary according to the actual operation of the hydropower station.