红壤坡面降雨入渗及产流产沙特征试验研究

Effect of Rainfall Intensities and Slope Gradients on Characteristics of Rainfall Infiltration,Runoff and Sediment on Red Soil

采用室内模拟降雨研究了不同降雨强度和坡度对红壤坡面降雨入渗、产流产沙的影响。结果表明:产流时间随降雨强度和坡度的增大而提前。对于入渗率较低的红壤坡面,径流强度主要受坡面承雨强度的影响,径流强度随雨强增大而增大,随坡度增大而减小。坡面入渗率随降雨强度的增大表现为先增大后减小。降雨强度增大能够增加水分入渗,但这种促进作用仅在一定的降雨强度范围内起作用。坡面入渗率随坡度增大表现为先增大后减小,20°左右存在一个坡面入渗率变化的临界坡度。坡面细沟侵蚀发展状况对稳定坡面入渗率有比较大的影响。径流率和入渗率与降雨历时的关系分别可以用幂函数和对数函数描述。在75,100 mm/h降雨强度下,产沙量随坡度的增大而增大,而50 mm/h降雨强度下,产沙量在20°时达到最大值而后出现下降,在20°附近存在一个侵蚀产沙量变化的临界坡度。

The effect of rainfall intensities and slope gradients on the characteristics of infiltration, runoff and sediment yield was investigated by rainfall simulation experiment of red soil. The results show that, the run- off occurring times were shortening with the increasing of rainfall intensities and slope gradients. For the red soil with poor permeability, runoff intensity was lower as slopes were steeper, while it increased with increasing rainfall intensity, and it was slope accepting rainfall dependent. With the increasing of rainfall intensities, average infiltration rate increased firstly and then decreased. Larger rainfall intensity can increases the average infiltration, but this effect only work in a certain range. For all the three rainfall intensities, average infiltration increased with increasing slope gradient firstly and then declined, there was a critical slope near 20°. Infiltration was affected greatly by the development status of rill erosion in slope. The sediment yield increased with slope increasing, and it reached to the peak values at 20° before declining for steeper slopes. Infiltration rate decreases with rainfall duration increasing and their relationship can be described by a power function. But the relationship between runoff intensity and rainfall duration can be described by a logarithmic function.