Simulation and Response of Runoff to Climate and Land-Use Changes in the Yanhe River Basin, Loess Plateau: A SWAT Model-Based Analysis

Ecological restoration projects in the Loess Plateau have significantly altered the underlying surface, which has profoundly affected the regional water cycle. In the context of the ongoing climate change, quantitatively identifying the factors influencing runoff changes and simulating runoff responses to various land management policies are essential for achieving sustainable development in arid/semi-arid regions. Daily hydrological and meteorological data from 1981 to 2020 along with the SWAT model were employed to analyze the attribution of runoff changes in the Yanhe River basin and simulate runoff responses under different climate and land-use scenarios. The results show the following: (1) the improvement of the underlying surface conditions appeared to be the leading factor of runoff retention, with a contribution of 81.21%, while the influence of climate change on runoff was minimal; (2) woodland generally exhibited superior performance in retaining runoff compared to grassland under diverse climate conditions; (3) converting farmland on slopes between 15 and 25 degrees into woodland and farmland on slopes exceeding 25 degrees into grassland demonstrated to be a more effective approach to controlling soil erosion; (4) it is recommended that a balance between water resource utilization and the extent of afforestation should be considered concurrently in future ecological restoration.