坡度对降雨径流挟沙能力影响的模拟试验

Simulation Experimental Study on the Impact of Slope Gradients on Sediment Carrying Capacity of Rainfall Runoff

高陡边坡降雨径流侵蚀输移能力是一个重要的科学问题。通过室内模拟降雨试验研究相同雨强不同坡度和坡长条件下的降雨径流侵蚀输移规律。结果表明:(1)试验条件下,水深与水力坡度的1/3次方呈负相关,与坡长的3/5次方呈正相关,流速与水力坡度和水深呈幂函数增加;(2)相同雨强裸坡条件下,径流含沙量与水力坡度的1/2次方呈正相关,与坡长的4/5次方呈正相关。水流挟沙能力约与水力坡度的1/2次方呈正相关。(3)降雨径流的水流紊动扩散作用与重力作用的比值较明渠水流偏大,表明雨滴打击的紊动作用较明显,给出挟沙能力公式。与常用的河流泥沙挟沙能力公式比较,系数偏大,指数偏小。研究成果对深入分析降雨径流侵蚀输移的机制具有重要意义。

Rainfall runoff erosion transport capacity of high and steep slopes is an important scientific problem.The law of runoff erosion transport under the condition of the same rainfall intensity and different gradients and slope length was studied by indoor simulated rainfall experiment.The results showed that:(1)Under the test conditions,the flow depth was inversely proportional to the 1/3 power of hydraulic gradient and directly proportional to the 3/5 power of slope length,and the flow velocity increased in positive proportion to hydraulic gradient and flow depth.(2)Under the condition of bare slope with the same rain intensity,the runoff sediment concentration was directly proportional to the 1/2 power of hydraulic gradient,was proportional to the 4/5 power of the slope length.The sediment carrying capacity of water flow was directly proportional to the 1/2 power of hydraulic gradient.(3)The ratio of the turbulent diffusion effect of rainfall runoff to the effect of gravity was larger than that of open channel flow,indicating that the turbulent effect of raindrops is more obvious,the formula of sediment carrying capacity is given.Compared with the commonly used formula of river sediment carrying capacity,the coefficient was larger and the index smaller.The research results are of great significance for in-depth analysis of the mechanism of rainfall-runoff erosion and transport.