Characteristics of Erosive Rainfall and Its Effects on Runoff and Sediment Yield in the Pupiaohe Basin, Western Yunnan

The runoff plot observation method was used to obtain rainfall and soil and water loss data from 2018 to 2022, and the discriminant clustering method was used to classify and identify erosive rainfall. The results indicate that: The monthly rainfall and erosive rainfall in the study area show a trend of first increasing and then decreasing over time, showing a single peak pattern. The rainy season is the key period for preventing and controlling soil erosion in the study area, with erosive rainfall accounting for 86.89% of the total amount. There are three main types of erosive rainfall in the study area, among which type I rainfall is characterized by high frequency, medium rainfall, short duration and moderate rainfall intensity, type II rainfall is characterized by medium frequency, medium rainfall, medium duration and light rain intensity, and type III rainfall is characterized by low frequency, heavy rainfall, long duration and light rain intensity. The sediment yield of type I rainfall was much higher than that of type II and type III rainfall, which was the main rain type that caused soil and water loss on the slope of the Pupiao River Basin, and under different land use types, the sediment yield of slope is most obvious in bare land and orange land. The influence of rainfall factors on runoff depth and sediment yield of different land use types in the study area was significantly different. Overall, rainfall erosivity was the highest, followed by rainfall and I₃₀, and the average rainfall intensity and duration were the least. The erosive rainfall mainly occurs in the rainy season in the Pupiao River Basin, western Yunnan, and the rain pattern and underlying surface are the main factors affecting the characteristics of sediment yield and loss on slope. The high coverage rate of vegetation and the implementation of furrow and ridge cultivation are effective measures to reduce sediment yield and loss on slope in the study area.