砾石覆盖条件下盐碱土边坡降雨侵蚀水动力学特征

为了探究砾石覆盖对盐碱土坡面侵蚀的减沙效应,通过室内模拟降雨试验,研究不同坡度和雨强条件下降雨径流水动力学特征及产沙受砾石覆盖的影响。试验坡度选取15°和30°,雨强选取92,119mm/h,坡面砾石覆盖度分别为0,10%,20%,40%,60%,80%,采用染色示踪法测定坡面径流流速。结果表明:不同坡度和雨强条件下,水流产沙率随坡面砾石覆盖度增大先增后减;雷诺数与弗劳德数均随砾石覆盖度增大呈先增后减的抛物线趋势,曼宁糙率、Dracy-Weisbach阻力系数、坡面径流剪切力和径流功率均与坡面砾石覆盖度呈线性正相关;径流功率预测产沙率效果较好,二者呈对数关系(R2=0.47)。

Hydrodynamic Characteristics of Rainfall Runoff on Saline-alkali Slope Covered by Gravel

A series of simulated rainfall experiments were conducted to investigate the reducing effect of gravel cover on erosion of saline slope. The effects of gravel coverage on hydrodynamic characteristics of runoff and unit sediment load were analyzed under different slope gradients (15°and 30°) and rainfall intensities (92 and 119 mm/h). The cover rates of gravel were 0, 10%, 20%, 40%, 60% and 80%, respectively. The flow rate was measured by dyeing tracer method. Unit sediment load increased first and decreased then with the increasing of gravel coverage under different slopes and rain intensities. The changing tendency of Reynolds number and Froude number versus gravel coverage was determined by parabola curve. Manning roughness, Dracy-Weisbach resistance coefficient, the stream average shear force and the stream power had positive liner relationship with the gravel coverage. The stream power predicted sediment load rate well, and these two were logarithmic (R2=0.47).