Effects Of Slope Length On Soil Erosion In Engineering Accumulation Slope Under The Condition Of Simulating Runoff

The production and construction project dig fill imbalance form engineering accumulation,which nearly 20 years has become the main source of sediment of new soil erosion.According to the principle of "damage prevention,ecological priority",reasonable control measures are laid on the slope of the engineering accumulation to improve the water and soil conservation function of the slope,and then improve the ecological environment.In order to optimize the prevention and control measures of the slope of the engineering accumulation in Loess Area,to maximize the benefits of slope protection measures.In this paper,the slope length is taken as the object of study.The influence of slope length on soil erosion in engineering accumulation slope is studied.In the field,runoff erosion tests are carried out on the simulated engineering accumulation runoff plot.5 slope length and 3 slopes are set to study the influence of slope length on soil erosion in engineering accumulation slope.The main conclusions are as follows:(1)The runoff rate in engineering accumulation slope increases with the discharge time.With the increase of slope length,the fluctuation amplitude of the rate sediment yield is also larger.The sediment concentration of runoff decreases first and tends to be stable with the water discharge scouring time.With the increase of slope length,the sediment concentration presents an increasing trend.The relationship between cumulative runoff and the water discharge scouring time can be expressed in a linear function.Cumulative sediment yield and water discharge scouring time shows a very significant power function relationship.Cumulative runoff and cumulative sediment increases with the increase of slope length.The experimental slope and slope length had an important influence on the cumulative runoff and sediment yield.The contribution of slope length to cumulative runoff and sediment yield is greater than that of slope.The slope length has a positive effect on cumulative runoff and sediment yield.Slope has a negative effect on cumulative runoff and sediment yield.(2)The rill width and rill depth increase with the water discharge scouring time.The relationship between rill width and time can be well described by logarithmic function.The rill width increases with the increase of slope length.The relationship between rill depth and time can be well described by linear function.The width-depth ratio of rill shows a trend of decreasing first and then steadily with time.The area of rill erosion shows a trend of increasing with the water discharge scouring time.The relationship between the area of rill and time can be well described by linear function.Under the different condition of slope and slope length,the distribution of the rill width is not consistent,showing diversity.In the case of small slope,the rill depth is high volatility.As a whole,the rill depth shows a trend of decreasing first and tending to be stable with the slope downward.(3)The flow velocity decreases first and tends to be stable with the water discharge scouring time.The relationship between flow velocity and time can be well described by logarithmic function.Reynolds number increases first and then decreases with time.Reynolds number decrease with the increase of slope length.The relationship between Reynolds number and time can be well described by the quadratic function.Because of the quadratic function opens downward,it is shows that the Reynolds number has maximum value in the experiment.As the runoff time continues,the Froude number decreases first and then tends to be stable.This shows that the slope runoff flow state continually develop to slow flow.With the increase of time,the resistance coefficient of slope surface is increasing.The resistance coefficient ranges from 0.017 to 12.14.With the increase of slope length,the relation between Froude number,resistance coefficient and time can be described by power function.(4)Soil erosion rate has significant linear function with flow shear stress and stream power.The corresponding soil erodibility parameter is 3.5×10-3s/m.The critical flow shear stress is 5.57 Pa.The fitting effect of erosion rate and flow shear stress is best.(5)There is a logarithmic function relationship between sediment concentration and slope length.The relationship between cumulative runoff and slope length can be well described by power function.There is quadratic function relationship between cumulative sediment yield and slope length.There is no significant relationship between rill depth and slope length.There is a significant quadratic function relationship between rill width and slope length.Because of the quadratic function opens downward,the maximum rill width exists.There is a linear relationship between flow velocity and slope length.Froude number,resistance coefficient,roughness coefficient,sediment carrying capacity and slope length exist significant exponential relationship.