Study On Erosion Mechanism Of Sand-covered Loess Slop

The most serious erosion area in the Loess Plateau is not in the water erosion area with the most rainfall,but in the wind erosion and water erosion crisscross area with the rainfall of about 400 mm.Based on the indoor simulated rainfall experiment,the sandy slope in the wind-erosion-water-erosion crisscross area is taken as the research obj ect,studying the characteristics of runoff yield,sediment yield and runoff sediment content of sandy loess slope and loess slope under intermittent rainfall and revealing the characteristics of runoff erosion and sediment yield of sandy loess slope.Based on the measured soil water content data,the paper studied the effects of slope surface on soil water content,soil wetting front,soil water redistribution process,infiltration rate and infiltration parameters under intermittent rainfall conditions,analyzing the influenlce of sandy slope on runoff p.rocess and mechanism.Main contributions of this paper are as follows:(1)Characteristics of runoff erosion and sediment yield on sandy slopes.The initial runoff yield time of sand-covered slope was 3.57 tirmes that of Loess slope,and the initial runoff yield time of rainfall on sand-covered slope was prolonged;the total runoff and the total sediment yield of sand-covered slope was higher than that of Loess slope.(2)Effect of sand cover on soil moisture.Sand cover on the slope could increase the infiltration of the slope on a certain extent.Redistribution of Water Content in Soil Layers on Sand-covered Slopes was lower than that on the Loess slope.(3)Law of hydrodynamic parameters before and after rill formation.For loess slope,four hydrodynamic parameters could well express the relationship between runoff and sediment concentration,however for sandy slope,only Re and resistance coefficient could better express the relationship between runoff and sediment concentration.(4)Correlation between rill morphological parameters and hydrodynamic parameters.On the Loess slope,Re and resistance coefficient can better express the variation of rill morphological parameters.On the sand-covered slopes,the influence of hydrodynamic parameters on rill morphological parameters is Re>resistance coefficient.