Attribution analysis of climatic and multiple anthropogenic causes of runoff change in the Loess Plateau-A case-study of the Jing River Basin

摘要

Over the past five decades, under the joint influence of climate change and human activity, river runoff in most areas of Loess Plateau showed a significant declining trend, which poses a great threat to ecological security and land degradation and soil erosion control. To identify the key factors controlling this decline and quantify the contribution rates of the multiple factors, a runoff simulation was established based on the Soil Water Assessment Tool (SWAT), and the influence of climatic and anthropogenic factors on runoff change was calculated by comparing the results of the simulation based on different modeling scenarios. First, the impact of climatic factors on runoff change was gradually decreasing over time, and the anthropogenic factors' impact was increasing based on the runoff observations. Second, the SWAT model proved to be reliable and acceptable for both the calibration and the validation periods, with R- 2 and Nash-Sutcliffe efficiency values both above .8. Third, the influence of climatic factors decreases from 85.70% to 42.43% but that of anthropogenic factors increases from 14.3% to 57.57% in different subperiods. Among the anthropogenic factors, the influence of the direct factor (water withdrawal) is growing the fastest, and the influence of indirect factors is increasing continuously. Therefore, future ecological management and water-related planning in Loess Plateau should consider the importance of human activity and the relationship between humans and the Earth. Finally, a range of comprehensive countermeasures are proposed to assist with sustainable watershed management in the Loess Plateau.