坡度对浅沟侵蚀产沙的野外放水冲刷试验影响

为了研究坡度对坡面浅沟侵蚀产沙的影响,以黄土丘陵沟壑区坡面浅沟为研究对象,选取野外实地坡面14.0°,18.5°,26.0°,29.0°坡度和5,10,15,20,25L/min放水流量进行典型野外坡面浅沟径流小区放水冲刷试验,研究坡度对浅沟径流率、产沙率、含沙量、总径流量、总产沙量的影响。结果表明:5,10,15,20,25L/min不同放水流量下,坡度与径流率、总径流量成正相关,既随着坡度增大径流率、总径流量增大;5,10,15,20,25L/min不同放水流量和14.0°,18.5°,26.0°,29.0°坡度下产沙率、含沙量和总产沙量随时间变化的规律一致,表现为试验时间内,均出现先增大—到达最大—波动减小—稳定趋势;产沙率、含沙量、总产沙量与坡度的关系表现为产沙率、含沙量、总产沙量随着坡度的增大先增大,达到最大值后减小,最大值出现在26.0°,26.0°的产沙率、含沙量和总产沙量分别为14.0°的1.06~2.87,1.31~2.21,1.08~2.77倍,产沙率、含沙量、总产沙量均存在临界坡度,临界坡度范围为18.5°~29.0°。

Experimental Study on the Effects of Field Scouring Slope on Ephemeral Gully Erosion and Sediment Yield

In order to study the effects of slope gradient on sediment yield by ephemeral gully erosion on slope surface, taking the ephemeral gullies on the hilly and gully slopes of the Loess Plateau as the research object, four slope gradients including 14.0°, 18.5°, 26.0° and 29.0°, and five discharge flows of 5, 10, 15, 20, 25 L/min, were selected to study the effects of slope gradients on runoff rate, sediment yield rate, sediment concentration and total runoff and total sediment yield. The results showed that the slope gradients were positively correlated with runoff rate and total runoff at 5, 10, 15, 20, 25 L/min, and the runoff rate and total runoff increased with the increase of slope. Under the different discharge flows and gradients, the sediment yield rate, sediment concentration and total sediment yield had the same trend over time:increasing first-reaching maximum-decreasing fluctuatingly-stabilizing finally. The relationship between sediment yield rate, sediment concentration, total sediment yield and slope gradient:sediment yield rate, sediment concentration and total sediment yield increased first and then decreased with the increasing slope gradients, and the maximum value appeared at 26.0°. The sediment yield rate, sediment concentration and total sediment yield at 26.0° were 1.06~2.87 times, 1.31~2.21 times and 1.08~2.77 times of those at 14.0°, respectively. There were critical gradients for sediment yield rate, sediment concentration and total sediment yield, which ranged from 18.5° to 29.0°.