Identifying the effects of climate change on discharge and sediment transport in a typical alpine basin

Global-scale changes in precipitation and temperature lead to regional variations in the hydrologic cycle. Understanding the impacts of climate change on discharge and sediment processes is crucial for effective watershed management, especially in alpine regions. A hydrologic modeling framework was established for the Yarlung Tsangpo River (YTR) watershed, the largest and longest river system on the Tibetan Plateau, which integrates the Soil and Water Assessment Tool (SWAT) with global climate models (GCMs) from the Coupled Model Intercomparison Project Phase 6 (CMIP6). The results highlight the importance of temperature in influencing hydrological elements during snowmelt periods in the northeastern and western parts of the YTR basin and precipitation across the entire basin during rainy periods. Compared with streamflow, sediment flux has been more sensitive to climate change over the past four decades. The annual mean streamflow is projected to decrease by −2.62% ± 0.88% in the near term (2025–2035) relative to the historical average of 1979–2014 but increases by 11.79% ± 3.72% and 38.67% ± 8.02% in the midterm (2040–2050) and long term (2060–2070), respectively. Moreover, the annual mean sediment flux trends upward throughout the study area, with changes of 1.13% ± 4.72%, 16.24% ± 5.89%, and 44.40% ± 12.80% in the near term, mid term, and long term, respectively. These results will enhance adaptive management and policy-making for alpine regions.