黄土坡面片流产流过程模拟研究

SIMULATED-RAINFALL EXPERIMENTAL STUDY ON RUNOFF OF SHEET FLOW ON LOESS HILLSLOPE

采用模拟降雨试验方法对黄土坡面片流产流过程进行了试验研究,试验雨强分别为1.00、1.33、1.67、2.00、2.33 mm min-1,坡度分别为9°、12°、15°、18°、21°。结果表明:1)不同雨强及不同坡度条件下,坡面片流径流率随降雨历时的变化均呈先增大后趋于稳定的趋势,不同雨强下较不同坡度下趋于稳定的时间早5 min左右,变化过程皆可用对数方程y=aLn(x)+b描述;2)坡面片流径流深随雨强及坡度的变化皆可用幂函数方程H=aIb和H=aSb描述;3)坡面片流径流深对坡度和雨强的综合响应可用二元幂函数方程H=3.83I1.01S0.490描述,且雨强的影响大于坡度;4)黄土坡面片流产流的片蚀效应显著,不同雨强及不同坡度条件下片流产流的片蚀效应分别表现为幂函数方程M=0.0378 H1.21及线性方程M=0.235H-3.48。

Sheet flow runoff on loess hillslope was studied through simulated rainfall experiments, under the condi- tions of rainfall intensities of 1.00,1.33,1.67,2.00,2.33 mm min - 1 and slopes of 9 °, 12°, 15 °, 18 °, 21 °. Results show that 1 ） regardless of rain intensity and slope degree, the runoffs displayed a general trend in rate, that is, increasing first and leveling off late, however, the turning point came 5 min earlier in treatments of rain intensity than in treatments ofslope degree, and the variation could be described with a logarithm equation y = aLn（x） ＋ b; 2） depth of the sheet flow runoff varied with rainfall intensity and slope gradient as well, which could be described with a power function equation H = aI^b and H = aS^b＂ respectively; 3）the integrated response of the runoffs in depth to rainfall intensity and slope gradient could be described with a dual power function equation H = 3. 831I^1.01 S^0.490 , and the response to rainfall intensity was grea- ter than to slope gradient; and 4）the effect of sheet flow runoffs on sheet erosion was significant, and varied with rainfall intensity and slope gradient, which could be described with a power function equation M =0.0 378 H^1.21 and a linear equa- tion M = 0. 235 H - 3.48 respectively.