Assessing the impact of climate change on water resources and extreme hydrological events in the Jialing River Basin

Global warming contributes to heightened precipitation variability and hydrological fluctuations. The Jialing River, abundant in water resources, necessitates a scientific assessment of prospective changes in water resources and extreme hydrological events to foster the harmonious development of the economy, society, and ecological environment. Current research predominantly delves into the historical runoff patterns of the Jialing River, with insufficient emphasis on predicting water resource responses and extreme hydrological events in the face of future climate changes. Utilizing the coupled Variable Infiltration Capacity Macroscale Hydrologic Model (VIC Model) and 22 climate models from the CMIP6 program, this study estimates the future runoff trends in the Jialing River Basin under the SSP1-2.6, SSP2-4.5, and SSP5-8.5 scenarios. Additionally, it analyzes the forthcoming evolution of extreme runoff event intensity and return periods within the basin through a coupled Bivariate Joint distribution. The findings indicate the following: (1) The VIC model demonstrates high applicability in the Jialing River Basin, as evidenced by a Nash-Sutcliffe Efficiency (NSE) exceeding 0.7 for daily runoff simulation at each station and a multi-year water volume error within 8%; (2) Future climate changes in the basin are anticipated to be predominantly warm and humid, with a projected 5.5% to 13.8% increase in precipitation and a temperature rise exceeding 2 ℃ from 2031 to 2090, compared to the reference period (1985-2014); (3) Runoff is likely to increase in the future, with a projected 7.0% to 14.0% rise from 2061 to 2090 compared to the baseline period (1985-2014); (4) The intensity of annual maximum one-day runoff and the annual maximum five-day water volume may increase in the future. Under the SSP5-8.5 emission scenario, the return periods for these events in the reference period (2061-2090) are shortened to 10-20 years each. While the future runoff variations in the Jialing River Basin under different climate scenarios remain uncertain, the hydrological outlook is less than optimistic. Strengthening comprehensive water resource management and flood risk mitigation capabilities is imperative.