模拟降雨条件下地表起伏对产流产沙的影响

揭示地表起伏形态对产流和产沙的影响及作用机理,为蓄水保土、调节径流和控制径流提供参考依据。通过野外人工模拟降雨试验,在3种降雨强度(60,90,120 mm/h)下,分析了5种起伏的地表(单凸起、单凹陷、凹凸相间、凹凸相连、光滑)坡面的产流产沙情况。结果表明:(1)在3种雨强下,5种地形的初始产流时间表现为:光滑地表单凸起地表单凹陷地表凹凸相间地表凹凸相连地表,且产流越早的地表其产流量和径流系数也越高;(2)在3种雨强下,5种地表的次降雨产沙量和产沙强度由小到大依次为:凹凸相连地表凹凸相间地表单凹陷地表光滑地表单凸起地表,产沙强度越大的地表其产沙过程越不稳定;(3)与光滑地表相比,地表凸起会加剧土壤流失,地表凹陷会减轻土壤流失,且凸起和凹陷组合的地表其减轻土壤流失的效应更显著;(4)降雨强度的增大会削弱不同地表起伏对产流产沙的影响。研究结论为地表起伏类型对坡面产流产沙有重要影响,光滑地表最易产生径流,凸起地表土壤流失最严重,凹凸相连地表蓄水保土效益最好。

Effects of Surface Relief on Runoff and Sediment Yield Under Simulated Rainfall Experiments

In order to study the effects of different surface relief forms on runoff and sediment yield during slope erosion process, five kinds of surface relief treatments (mounds, depressions, Intervals mound and depression, continuous mound and depression, smooth) were set up. The runoff and sediment yield of each treatment under three rainfall intensities (60 mm/h, 90 mm/h, 120 mm/h) by field artificial rainfall experiments were analyzed. The results showed that:(1) Under three rain intensities, the initial runoff time of the smooth surface was the shortest, while the continuous mound and depression surface was the longest. The initial runoff time of intervals mound and depression surface was close to continuous mound and depression surface, while mounds surface was just a little longer than the smooth one. The runoff time of depression surface was in the middle. The shorter the initial runoff time was, the bigger the runoff volume and runoff coefficient were. (2) Under the same rain intensity, the sediment volume and sediment yield intensity of different treatments ranked as:continuous mound and depression surface < intervals mound and depression surface < depressions surface < smooth surface < the mound surface. The greater the sediment yield intensity was, the more unstable the sediment yield process was. (3) Compared to the smooth surface, the mound aggravated soil loss, while the depression reduced soil loss. When mounds and depressions were combined, the reduction of soil loss was more significant. (4) Increasing rainfall intensities weakened the effect of different surface reliefs on runoff and sediment yield. The conclusion was that the different types of surface relief affected the runoff and sediment yield significantly. Runoff occurred most easily on smooth surface, and soil loss was most serious on mound surface, as well as the conservation of soil and water was best on continuous mound and depression surface.