Study On The Influence Of Water Erosion On The Micro-topography Of The Slope In The Bare Arsenic Sandstone Area

Slope erosion is one of the important components of soil erosion research,and Pisha Sandstone is the main source of coarse sediment in the Yellow River.The study on the influence of hydraulic erosion on the micro topography of bare Pisha Sandstone slope is not only helpful to understand the process of hydraulic erosion of slope micro topography,but also provides the basis for the prevention and control of soil erosion and ecological environment protection.In this thesis,the slope rill formed under natural conditions in Baojiagou watershed of Nuanshui Township in the west of Zhungeer banner,Ordos City,Inner Mongolia Autonomous Region is studied,Using rigel-400 three-dimensional laser scanner,through runoff plot monitoring and field flushing test.Based on this,the change characteristics of slope terrain factors,rill size and morphology in each period were analyzed,and the evolution law of rill formation under field natural conditions was revealed.The law of erosion and sediment yield and the change process of micro topography on the slope in the exposed soft rock area are clarified,and the influence of rainfall and scouring on the runoff and sediment yield process on the slope is analyzed,The main research results were showed as follows:1.The rainfall types in the study area are divided into light rain,moderate rain and heavy rain.Moderate rain and heavy rain have a greater impact on slope erosion.Moderate rain has the largest contribution to runoff and sediment on bare bedrock slope.Runoff rate and sediment yield change with rainfall intensity.Rainfall parameters can be fitted with the amount of erosion by function.The slope erosion in the study area is mainly 0-1cm micro erosion,with the increase of rainfall times,The development process of the slope rill during a single rainfall is summarized as: splash erosion-chip erosion-ridge drop-continuous rill-traceable erosion-ditch wall collapse-channel stability,With the increase of rill width and depth,the ratio of rill width to depth decreases,and the values of rill density,rill surface area,rill complexity and rill fragmentation increase,The width depth ratio of rill in Δ DEM increased,but other morphological indexes did not change;Rainfall can significantly change the micro topography of bare slope bedrock,and the terrain factors increase with the increase of rainfall times,indicating that rainfall is developing in favor of erosion.2.The runoff rate of different scour discharge and different slope increases with the duration of scour time,while the sediment yield first increases and then decreases with the duration of scour time,The runoff rate and sediment yield rate can be fitted by a functional relationship,and the influence of slope on the runoff rate and sediment yield rate is greater than the influence of the erosion flow on the runoff rate and sediment yield rate.The slope with a smaller slope of 5 ° and 10 ° shows the shape of the rill as "inverted trapezoid" and "U-shaped",and "wide and shallow",On 20 ° and 30 ° slopes with larger slope,the rill shape is "deep V" and "V",and "narrow deep",As the width depth ratio of rill decreases,the values of gully density,rill surface area,rill complexity and rill fragmentation increase,The width depth ratio of rill in Δ DEM increases,other morphological indexes have no change,and the increase of slope is more conducive to the development and maturity rate of rill than the scouring flow.The increase of slope has a greater effect on the micro topography than the change of scour flow,and the values of surface roughness,surface relief and surface cutting are larger,The topographic factors of the two adjacent scour ΔDEM also increase with the increase of scour flow and slope gradient.3.The morphological index of rills and the amount of erosion under natural rainfall conditions show a significant correlation,and the morphological indexes of rills and the amount of erosion show a very significant correlation under the condition of erosion;the topographic factors of micro-topography and the amount of erosion under natural rainfall conditions Significant correlation,the topographic factors of the micro-topography and the amount of erosion under scour conditions show an extremely significant and significant correlation.