坡面细沟流速与坡度关系的数值模拟

Numerical Simulation of Rill Flow Velocity and Gully Development for Different Hillslope Gradients

对于相同的净雨强过程 ,分别采用动力波模式 (一维非恒定流方程组 )和运动波模式计算了不同细沟宽度下沟内流速与坡度的关系。计算结果表明 ,动力波模式的最大流速对应的坡度约为 35°,而运动波模式的最大流速对应的坡度约为 45°。在坡面土壤的起动流速为恒定值的情况下 ,最大流速对应的坡度就等于细沟沟宽发展最大的坡度 。

The relationship between rill flow velocity and hillslope gradient is numerically studied using both a 1 D kinematic wave model (i.e., Chezy formula and continuity equation) and a 1 D dynamic wave model (i.e., 1 D Saint Venant equation and continuity equation),for various net rainfall intensity and hillslope gradient conditions.Numerical results indicate that each model predicts a different slope gradient corresponding to the maximum rill flow velocity. For the dynamic wave model the maximum velocity takes place on a 35° slope, and for kinematic wave model it is 45°.The dynamic wave model is used to predict rill and gully development on hillslopes with different gradients. For a given critical soil detachment velocity, maximum rill width will develop on a 35° slope,which means that rill development is most active on such slopes.