Quantitative impacts of climate change and human activities on the runoff evolution process in the Yanhe River Basin

Abstract

Since 1999, the surface vegetation coverage in the Yanhe River Basin has undergone constant change. The ecological environment in the basin has improved partially; however, water scarcity remains a critical issue for the Loess Plateau. The current quantitative analysis of runoff evolution affected by climatic and anthropogenic elements in the study area is insufficient. To evaluate the influence of anthropogenic elements and climatic variation on runoff evolution, we used the SWAT hydrological model to study key hydrological processes under different simulation scenarios along the river basin in this study. Overall, the runoff volume of the Yanhe River Basin showed a significant downward trend, although different trends were observed over different periods. Runoff declined from 1981 to 1998 and increased after 1998. A comparative analysis of three different scenarios shows that climate change contributes approximately twice as much to runoff evolution as land use changes. Climate change causes runoff to decrease by 65.64%, whereas land use change causes runoff to increase by 34.36%. The decrease in runoff in small watersheds is primarily due to climatic factors, whereas vegetation restoration is beneficial to the increase in runoff in small watersheds. The research results will be valuable in comprehending the quantitative influence of climatic and anthropogenic factors on the hydrological evolution of the Yellow River Valley.