Erosion Effect of Rainfalls on Loess Plateau Soil and Its Experimental Researches

摘要

Based on the theoretical analysis on the rain erosion force index, this study researched the rainfall characteristics in Yangling loess area and its erosion on slope land. It chose the large runoff observation field in Yangling City which located in Shanxi Province in western Loess Plateau of China, as the experimental subject. Meanwhile, the field measurements from 2009 to 2013 were adopted as the experimental data. The results show that the magnitude and direction of the wind affect the splash erosion angle between raindrop and ground during the rainfall in Loess Plateau region. That is, the values of cos(θ + γ) greatly affect the erosivity. In the Loess Plateau region, the rainfall intensity and raindrop kinetic energy have the most significant impact on the splash erosion. The rainstorms usually have high energy. So the erosivity of Loess Plateau rainstorm on the soil is much higher than the ordinary rainfall. At the same time, the Loess Plateau region rainfalls have obvious monsoon rain characteristics, causing the concentrated time distribution of sloping field soil erosion. The rainfall in July and August is 52.7% of the rainfall during the total research time from May to September, and the erosive rainfall is 69.1% of it. The erosion amount in July and August is 77.4% of the annual erosion. The experiments show July and August are the critical period to control water and soil erosion.