Attribution identification of natural runoff variation in the Yiluo River Basin

Study region: The Yiluo River Basin between the Sanmenxia Dam and the Huayuankou Station of the Yellow River basin. Study focus: The current research is designed to spatially identify different driving factors' contributions to natural runoff variation. The Water and Energy Transfer Process model was used to simulate the runoff of 2044 sub-basins. Based on this, trends of runoff variation were analyzed, and then, the mutation year of runoff variation in each sub-basin was detected. Moreover, the contribution rate of climatic variation and anthropogenic factors on runoff change in each subbasin was quantified. New hydrological insights for the region: The annual natural runoff in 90.66% of sub-basins and the flood-season (May to October) natural runoff in 45.99% of sub-basins showed declining trends. And the mutation year of runoff change mostly occurred in the 1970 s and 1980 s. The natural runoff change was primarily affected by climatic variation. The contribution rate of climate to the annual and flood-season natural runoff was 69.32% and 71.51%, respectively. While the contribution of man-made activities to the annual and the flood-season natural runoff was 30.68% and 28.49%, respectively, and the high-impact areas were largely distributed downstream. The research provides scientific support for developing and regulating water and land resources in the Yiluo River Basin.