雨强和坡度对嵌套砾石红壤坡面产流产沙的影响

采用人工模拟降雨的方法研究了嵌套砾石红壤坡面的产流产沙特征,分析了雨强(60,120mm/h)和坡度(10°,15°,20°,25°)条件下嵌套砾石和无砾石红壤坡面的产流和产沙过程差异。结果表明:(1)产流开始时间T_(嵌套砾石)T_(无砾石),60mm/h雨强条件下嵌套砾石较无砾石坡面在10°,15°,20°,25°坡度分别延迟4.20,2.95,2.23,1.03min;(2)坡度相同时,嵌套砾石坡面较无砾石坡面产流率明显减少,但雨强的增大会掩盖嵌套砾石对坡面产流率减小的影响;(3)嵌套砾石红壤坡面在60mm/h雨强、坡度10°条件下平均产流率最小,在120mm/h雨强、25°坡面下平均产流率是前者的4.5倍;无砾石红壤坡面在120mm/h雨强、坡度25°条件下平均产流率最大,为最小平均产流率的4.8倍;(4)各坡面产沙强度、次降雨产沙量随雨强和坡度增大而增大,60mm/h雨强、坡度10°和25°时,嵌套砾石坡面平均产沙强度为无砾石坡面的6.0%和28.4%;120mm/h雨强时,此两个坡度的嵌套砾石坡面为无砾石坡面平均产沙强度的33.9%和25.3%。

Effect of Rainfall Intensity and Slope Gradient on Runoff and Sediment Yield on the Red Soil Slope Nested Gravel-sand

The characteristics of runoff and sediment yield on the red soil slope nested gravel-sand were studied through artificial simulated rainfall, and the differences of runoff and sediment yield between nested gravel red soil slope and no gravel slope under the conditions of rainfall intensity (60,120 mm/h) and slope gradient (10°, 15°, 20° and 25°) were analyzed. The results were as follows:(1) The start time of production runoff (T) on the nested gravel slope was less than that on the no gravel slope, and compare with no gravel slope, the runoff production time on the nested gravel slope was delayed 4.20, 2.95, 2.23 and 1.03 min, respectively, when the slope gradient was 10°, 15°, 20° and 25° under the rainfall intensity 60 mm/h. (2) When the slope gradient was the same, the runoff rate of the nested gravel-sand slope was less than that of no gravel slope obviously, but the increase of rainfall intensity could cover up the influence of nested gravel-sand on the decrease of runoff rate. (3) When the rainfall intensity was 60 mm/h and the slope was 10°, the average runoff rate of nested gravel-sand slope was the lowest, while the average runoff rate was 4.5 times higher than the lowest value when the rainfall intensity was 120 mm/h and the slope gradient was 25°. When the rainfall intensity was 120 mm/h and the slope gradient was 25°, the average runoff rate of no gravel-sand slope was 4.8 times higher than the lowest. (4) The sediment yield intensity and the amount of sediment yield increased with the increasing of rainfall intensity and slope gradient. When the rainfall intensity was 60 mm/h and the gradient was 10° and 25°, the average sediment yield intensity of nested gravel-sand slope was 6.0% and 28.4% of the no gravel slope, respectively. When the rainfall intensity was 120 mm/h, the value was 33.9% and 25.3%, respectively.