Experimental Research Of Soil Erosion And Sediment Yield Characteristics Of Loessial Soil In The Western Of Shanxi Province

The loess plateau in the western of Shanxi Province has steep slopes,ravines,and also lack of plants.The short and heavy rainstorms often cause severe soil erosion.Taking the Wangjiagou watershed in western Shanxi as the research object,this paper used indoor artificial rainfall simulation test to discuss the three aspects of runoff,infiltration and eroded rill morphology under the rainfall conditions,in order to provide theoretical guidance for the control of soil erosion on the slope of the area.The main findings are as follows:(1)Impacts of runoff on erosion and sediment production:The slope runoff of secondary rainfall increasing with the increase of rainfall intensity and slope length.The longer the slope length is,the larger it increase.The flow state of slope runoff is laminar and rapid.It has a big impact on sediment production(correlation coefficient is greater than 0.85).Runoff and sediment yield showed a significant positive correlation in the 0.01 level(correlation coefficient is 0.98),the relationship between them can be described by the linear equation(R~2>0.93);There is a significant linear relationship between runoff shear and sand transport(R~2>0.92).(2)Influence of infiltration on erosion and sediment production:The time of onset of slope runoff is negatively correlated with rainfall intensity and early soil moisture content(R~2>0.85);the closer it to the bottom of the slope,the higher the soil infiltration rate is.The soil infiltration rate is increasing with the volumetric moisture content.On the other hand,the volumetric moisture content of soil is decreasing with the increase of soil depth.The infiltration rate and the sediment yield are positively correlated at the 0.01 level.The stronger the rain intensity is,the smaller the correlation is(the variation coefficient of rain intensity was 0.90~0.41.);10cm depth of soil infiltration rate and sediment production is greater than the 5cm,15cm,and 20cm soil depths in the correlation of the 0.05 level.(3)The influence of slope fine rills on erosion and sediment production is:Three indicators of fine rill density,splitting degree and width-depth ratio were used to describe rill morphology.The results showed that the ratio of ridge length to fine rill density and rill width and depth was more sensitive than rainfall.And the rainfall intensity is more sensitive than the slope length to the effect of fine groove digging;the overall soil stability of the loessial soil in the west of Shanxi Province is poor,and the soil is loose and porous.The randomness of the ravine development is relatively large,and the ravine is sloped from the slope.The rill developed from the mid-lower part of the surface,which is characterized by falling ridges,fine rills,fine rills,and fine groove collapses.The erosion yield rate is significantly positively correlated with the fine rifting degree at the 0.01 level(the correlation coefficient was 0.97).The density of the rill showed a significant positive correlation at the 0.05 level(correlation coefficient was 0.71).