| Overland flow is the beginning of surface runoff and is also one of the key factors that cause soil erosion and sediment transport.The study on hydraulic characteristics of overland flow is the basis of the prediction model of soil erosion,which is of great significance to solve the engineering problems.In this paper,the simulated rainfall and runoff experiments under different roughness conditions are designed to analyze the influence of rainfall intensity,roughness,slope,runoff on hydraulic characteristics.The main research achievements are as follows:(1)The runoff experiments.When d≤0.35 mm,due to the influence of the viscous sublayer,the overland flow resistance is small,the flow velocity is positively correlated with slope,and the depth of runoff is negatively correlated with slope.The overland flow resistance coefficient f is approximately equal to a constant.When d>0.35 mm,the slope has less influence on velocity and depth.And the overland flow resistance coefficient,which is negatively correlated with the flow rate,is positively correlated with slope and roughness.There is a power function relation between overland flow resistance coefficient and roughness,flow and slope.(2)The simulated rainfall experiments.The rainfall has a deceleration effect on the overland flow,and the velocity is negatively correlated with the rain intensity.Rainfall has two opposite effects on overland flow resistance coefficient.Rainfall resistance is positively correlated with rain intensity.With the increase of roughness,the proportion of rain resistance in total resistance increases.When d<0.35 mm,the rain resistance is small due to the fast velocity,the particle resistance is also small due to the influence of viscous sublayer.Therefore,the resistance coefficient.f is approximately equal to a constant.When d>0.35mm,there is a power function relation between resistance coefficient and slope,rainfall intensity and runoff. |
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