Influences of Rainfall and Underlying Surface Conditions on Soil Erosion and Sediment Yield in Yanshan Rocky Mountain Area
Based on the observation data of runoff plots,soil erosion and sediment yield characteristics and its influencing factors on slope scale were analyzed in order to reveal the law of water and soil loss in Yanshan rocky mountain area.This research can provide a reference for regional soil erosion control.The results showed that the average rainfall intensity and rainfall excess for runoff yield were the main factors inducing slope erosion,and the correlation between the rainfall duration and eroded sediment yield was not obvious.The erosion modulus of the runoff plots show exponential growth with the increasing slope gradients,and the erosion modulus showed a rapid increasing trend when the slope gradient was over 20.42° respectively.The critical slope length is about 22 m,when the slope length is less than 22.26 m,the soil erosion modulus increases with the increase of slope length,but after the slope length exceeds 22.26 m,the erosion modulus decreases gradually.The erosion modulus decreased as vegetation coverage increased.However,there was little difference between the erosion modulus of the grassland runoff plots with vegetation cover of 60% and 90%,which indicated that there was a critical vegetation coverage in soil loss control.Land preparation measures such as terrace,fish-scale pit and level bench can effectively store water and retain sediment as well as reduce slope erosion by changing underlying surfaces.