Impacts of different human activities on hydrological drought in the Huaihe River Basin based on scenario comparison

The catchment above Bengbu in the Huaihe River Basin, China In the Anthropocene, hydrological drought is significantly affected by human activities, and the degree of different human activities affecting droughts may vary in different physiographic and anthropogenic contexts. This study aims to quantify the relative contributions of various human activities on hydrological droughts using “scenario comparison” method based on a calibrated PCR-GLOBWB model. The impacts on hydrological droughts by human activities exhibit large differences over time and space. In terms of time, non-irrigation water use (NWU) and irrigation water use (IWU) increased standardized drought streamflow deficit (SDSD) by about 119 % and 214 % on average during 1981–2010, respectively. In terms of space, NWU heavily increased SDSD in most regions of the basin, whereas reduced it in the regions with limited surface water due to the return flow from unconsumed water to surface water. IWU reduced SDSD in paddy irrigation regions due to large quantities of water in the upstream rivers were transferred to those regions for flooding irrigation, whereas in non-paddy irrigation regions IWU increased SDSD due to most of water being withdrawn locally and comparatively small quantity of water transfer. Reservoir operation (RO) reduced SDSD in downstream water receiving areas while increased SDSD in upstream areas. Our findings can help drought management and mitigation.