Unraveling future hydrological and sediment dynamics through an integrated GCMs-PLUS-SWAT coupling framework.

Area of Science:

• Hydrology and Climate Science
• Environmental Modeling
• Water Resource Management

Background:

• Global climate change and anthropogenic activities are driving complex evolutions in watershed hydrological cycles.
• The Yangtze River Basin faces significant environmental pressures, necessitating advanced modeling for future projections.

Purpose of the Study:

• To construct a comprehensive SWAT hydrological model for the Yangtze River Basin.
• To quantify projected hydrological element evolution under different climate and land-use change scenarios (SSP245 and SSP585).
• To provide a scientific basis for integrated watershed management and ecological conservation.

Main Methods:

• Integrated a SWAT hydrological model with CMIP6 climate projections and the PLUS land-use change model, creating a "GCMs-PLUS-SWAT" framework.
• Utilized multi-resolution data to delineate sub-basins and hydrologic response units (HRUs).
• Validated the model for streamflow and sediment load simulations, achieving high accuracy (R² = 0.83-0.95 for streamflow, R² = 0.82-0.85 for sediment).

Main Results:

• Projected significant increases in precipitation and temperature, with higher rises under the SSP585 scenario.
• Observed intensified seasonal heterogeneity in erosion, with declining summer sediment loads and increasing autumn/winter loads.
• Predicted substantial increases in annual streamflow under SSP585, with notable intra-annual redistribution and a dramatic near-term sediment load surge in the upper basin.

Conclusions:

• Water-sediment processes exhibit asymmetrical responses to high-emission scenarios, with significant spatiotemporal divergence.
• Hydraulic engineering plays a crucial role in stabilizing sediment loads in the mid-lower basin.
• The findings offer critical insights for sustainable water resource management and ecological protection in the Yangtze River Basin.