Experimental Study On Dynamic Process Of Soil Erosion On Slope Of Disturbed Soil Accumulation

With the demand for western development and promoting regional economicdevelopment, the Loess Plateau production, development construction projects, moreand more disturbed soil erosion resulting accumulation of soil brought increasinglyprominent. Since being violent disturbances, loosely packed soil of the original soilstructure is destroyed, and often lack the protection of soil and water conservationmeasures and plant measures under storm conditions are prone to severe soil erosionand destruction of farmland, roads, etc. a huge loss to life and property of the people.In order to investigate the disturbance of soil erosion characteristics change with theaccumulation of soil slope and initial hydrodynamic conditions, we have built astandard test cell, to explore the reasons for its three slope, drainage flowcharacteristics of the next four and occurrence of soil erosion and processes. Throughthe entire testing process the following conclusions:(1) From the point of view of soil erosion characteristics of the cell: theproduction flow rate variation under the test conditions consistent over time, showedsteady increases first and then change the basic characteristics; average productionflow rate and drainage flow positive linear correlation relationship; at30L/min flowrate of the total runoff and drainage slope no obvious relationship with the slope ofthe total runoff increases other traffic. Cell sediment rate variation with time differentin different slope drainage flows are not entirely consistent, basically showingvariation of the following two kinds:â‘ at maximum drainage flow, sedimentproduction rate increases rapidly at first, then gradually decreases, and finallystable within a certain range;â‘¡in other cases, sediment production rate increases first and then basically stable. The average sediment flow rate and drainage, slopelinear relationship existed, but the significance level (Sig. value) Ma-Q regressionequation than Ma-S regression equation significant level, indicating that comparedwith the slope drainage greater impact on the average sediment flow rate.(2) Sediment concentration variation with time what has three main kinds:â‘ turn on the water flow is small and the slope is small, the sediment concentration overa long period of time basically stable in the late test (18min) gradually decreases.â‘¡Large or steep drainage flows when runoff sediment concentration early (9~12minago) decreases after.â‘¢Between sediment concentration between the first two casesreduced with time small.Average runoff sediment concentration and drainage flowwas a negative linear correlation with the slope of the linear positivecorrelation. Runoff and sediment relations under test conditions which can be used topower function y=axbexpression, a value change between0.388~1.445, b valuechanges between0.256and0.911; Brainage flow and slope with a valueincrease increasing, and b values continue to decrease; when the drainage flow60L/min, although still showing a positive correlation between runoff and sediment,but the power function has not fit well the relationship between the two.(3) The flow rate of each water distribution in the cell middle (vertical section3)are stable in the presence of a flow velocity0.3~0.5m/s in cross-section. Section inthe section above, the average velocity over time as a whole showed a decreasingtrend drainage in the following section of this section, the average velocity over thewhole drainage time an increasing trend. The average depth of each observationsection of the drain with the extension of time are increasing; in the upper part of thecell (section1and2) with an average depth of rapid change, and in the lower part ofthe cell (sections3-5) average water depth is more soothing and has been at the inbetween0.5mm~1mm; average depth of the drainage flow is no obvious relationship.(4) Under the experimental conditions substantially laminar flow overland flowonly in sections1and part-time for the transition flow; addition to individualphenomenon, the overland flow are rapids areas; Froude number under the variousdrainage flow and Reynolds number are negative correlation; drag coefficient andReynolds number exponential relationship exists, but no significant relationship with the drainage flow.Analysis of changes in slope along the length of the drag coefficientwas found, slope length within the range of0to6m intense soil erosion is a major partof overland flow in the supply of sediment;6~20m slope length within the range ofweak soil erosion in the region on the slope surface stream sediment supply remains,but the slow rate of supply. Slope resistance coefficient and a positive linearcorrelation between the depth of the water, so basically the same features and changesin water depth.(5) Flow shear stress increases with slope length changes can be well explainedby the cell soil erosion occurs mainly in the area of the upper part of the reason (0~10m).Although there is a good flow shear stress linear relationship with unit area ofsoil erosion rate, but due to the ability to represent the flow shear flow and erosion ofsoil particles into overland flow, and the slope of the selected test areas are steep,gravity erosion the strong performance of the erosion model is not suitable to explainthe change in erosion rate under the test conditions. Since water is a reflection of thepower handling capability of overland flow, so the stream power model can be appliedto the experimental conditions down to reflect the changes in soil erosion rates.