移动降雨条件下坡面产流产沙过程试验研究

通过对降雨移动方向上不同雨强和降雨历时的研究,揭示移动降雨坡面产流产沙关系及其变化规律,采用2个降雨移动方向(沿径流向上和向下移动)、2个雨强(1.35,2.75mm/min)和2个降雨历时(60,120min)在室内进行模拟移动降雨试验,分析不同降雨移动方向、不同雨强和降雨历时坡面产流产沙特征。结果表明:(1)向上移动降雨,相同历时(相同雨强)条件下,大雨强(长降雨历时)初始产流时间为140s(240s),比小雨强(短降雨历时)提前165s(65s)。(2)向下移动降雨,雨强越大,降雨历时越短,产流产沙曲线越陡峭;产流量和产沙量达到峰值的时间一致。(3)与向上移动降雨相比,向下移动降雨初始产流平均时间、产流和产沙达到峰值的平均时间分别滞后了2 210,2 468,2 948s;产流总量和产沙总量分别减少了13.08%~74.90%和42.95%~84.24%,但产流和产沙峰值大小没有明显变化规律。(4)不同降雨移动方向,坡面累计产沙量和累计产流量之间的函数表达式不同。

Experimental Study on the Process of Runoff and Sediment Yield under Moving Rainfall

The spatial and temporal distribution of rainfall was an important factor influenced runoff and sediment yield. Based on the study about rainfall intensities and rainfall duration under the different moving rainfall directions, the relationship between runoff and sediment yield and its variation regularity was expected to be revealed. In this study, the indoor simulated moving rainfall experiments of 2 moving directions (up and down movement), 2 rainfall intensities (1.35 mm/min, 2.75 mm/min) and 2 rainfall durations (60 min, 120 min) were carried out in order to analyze the runoff and sediment characteristics under different moving rainfall directions, intensities and durations. The results showed as follows: (1)For the moving upstream rainfall, with the same rainfall duration (rainfall intensity), initial runoff time of heavy rain (long rainfall duration) was 140 s (240 s), 165 s (65 s) earlier than that of light rain (short rainfall duration). (2)For the moving downstream rainfall, the stronger rainfall intensity was and the shorter rainfall duration was, the steeper runoff and sediment yield curve was. The time of runoff and sediment arrived peak value was identical. (3)Compared with the moving upstream rainfall, the average time of initial rainfall runoff, runoff and sediment reached the peak lagged 2 210 s, 2 468 s, 2 948 s, respectively, in the moving downstream rainfall. The total of runoff and sediment yield reduced by 13.08%~74.90% and 42.95%~84.24%, respectively, but the peak value of runoff and sediment were not obvious change rules. (4)The function expressions of cumulative runoff and sediment yield were different under different moving rainfall directions.