Effects of Rainfall and Vegetation on Runoff and Sediment Yields in a Typical Plot of Xiangjiang River Basin

In order to reveal the characteristics of the runoff and sediment yield patterns of different vegetation types under erosive rainfall in purple soil, based on the daily measured data from 2017 to 2021 at the Soil and Water Conservation Experimental Station in Hengdong County, Hunan Province, four runoff plots were selected, namely bare land, forest land, agricultural land, and grassland. By using the cluster analysis method, 132 erosive rainfall events were classified into three different rainfall types: A (with large rainfall amount, large rainfall intensity, and long duration), B (with large rainfall amount, small rainfall intensity, and long duration), and C (with small rainfall amount, large rainfall intensity, and short duration). According to the analysis, among the three types of erosive rainfall, the type with the lowest occurrence frequency was type B. The rainfall amount of the three types of rainfall had a greater impact on runoff volume than on slope erosion-induced sediment yield. The rainfall type with the largest cumulative runoff and sediment yield was type B. The cumulative runoff and sediment yield of the four land types in ascending order was bare land > agricultural land > grassland > forest land. Compared with that by bare land, the runoff and sediment reduction by forest land was higher, being 20.4% and 70.4%, respectively. Moreover, the runoff and sediment reduction by various vegetation types was the highest under type B rainfall. Overall, the sediment reduction was greater than the runoff reduction.