Responses to future climate change in hydrological processes and hydrological drought in the upstream of Shiyang river basin, Northwest China

Study region: The upstream of Shiyang River Basin (SYRB) situated in the eastern region of the Arid Region of Northwest China (ARNC). Study focus: The response of hydrological processes and hydrological drought to future climate change across four SSPs scenarios. New hydrological Insights: We applied a modified SWAT+ model that incorporates glacier hydrological processes, combined with ten CMIP6 outputs across four SSPs scenarios, to simulate future hydrological processes. The standard streamflow index and run theory were then used to investigate the characteristics of hydrological drought. The valuable results are summarized as follows: (1) The modified SWAT+ model demonstrates satisfactory performance in the upstream of SYRB, with NSE greater than 0.70 and PBIAS less than 10 % during the calibration and validation phases. (2) Under the influence of climate warming, evapotranspiration is projected to increase annually, while soil water content generally falls below baseline conditions. The changes in runoff closely follow precipitation variations, all of which changes simultaneously. The increase in precipitation is primarily converted into runoff, while a smaller proportion contributes to evaporation and soil water recharge. (3) Compared to historical period, the characteristics of hydrological drought in the future indicate that the study area will experience more frequent and severe hydrological drought. Extreme hydrological drought events are projected to become longer and more intense. Hydrological drought is more easily influenced by meteorological drought from the perspective of drought propagation.