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径流流速不仅是坡面径流的重要水动力学特性,而且是计算其他水力特性及侵蚀产沙的重要参数,本文目的在于研究坡面细沟流和细沟间薄层水流流速沿坡面的变化过程,比较细沟和细沟间径流流速的差别。实验选取1 m、2.5 m、4 m、5.5 m、7 m、8.5 m和10 m共7个坡长的小区(均为5°),装填粉壤土,采用历时2 h、总雨量121 mm的变雨强人工模拟降雨,在固定的降雨时段用染色法测量不同坡段细沟和细沟间的径流流速,每个坡长进行干、湿运行降雨各1场,两者间隔24 h。结果表明:(1)在各坡长上,细沟间薄层水流流速小于相应坡段细沟内的径流速度,细沟间流速变化于0.03~0.1 m/s,而细沟内流速的变化范围为0.15~0.45 m/s,整个坡面平均细沟流速是细沟间流速的2~4倍。(2)细沟和细沟间流速是距坡顶距离L的幂函数,对于细沟流速,L的指数为0.409~0.420,对于细沟间流速,L的指数为0.175~0.218。(3)平均来说,各坡长细沟流速为湿运行大于干运行,且随着距坡顶距离增加,湿运行细沟流速增加较快;而细沟间流速正好相反。本文揭示了细沟和细沟间流速沿坡面变化的基本特征及其差异,有助于深入认识细沟、细沟间侵蚀机理的差异。
The runoff velocity is not only an important hydrodynamic characteristic of slope runoff, but also an important parameter for calculating other hydraulic characteristics and sediment yield. The purpose of this paper is to study the variation of flow velocity along the slope between thin- Process, compare the difference between the flow velocity between the rill and the rill. A total of seven slope length plots of 1 m, 2.5 m, 4 m, 5.5 m, 7 m, 8.5 m and 10 m were selected in the experiment. All the plots were filled with silty loam and the soil samples were collected for 2 h with a total rainfall of 121 mm Rainfall was simulated by artificial rainfall. The runoff velocity between rill and rill at different slope sections was measured by dyeing method in a fixed rainfall period. Each slope length was subjected to dry and wet run-off rainfall of 1 field with an interval of 24 h. The results show that: (1) The velocity of thin-layer flow in the thin-ditch is smaller than that in the corresponding thin-ditch on each slope length. The velocity changes between 0.03 and 0.1 m / s, while the variation of velocity The range of 0.15 ~ 0.45 m / s, the average rill flow velocity across the slope is 2 to 4 times the velocity between the rill. (2) The flow velocity between the thin-ditch and the thin-ditch is the power function of the distance L from the top of the slope. The index of L is 0.409 ~ 0.420 for the velocity of the thin-ditch and 0.175 ~ 0.218 for the velocity of the thin-ditch. (3) On average, the velocity of runners in wet run was greater than that in runners, and the velocity of wet run increased rapidly with the increase of the distance from the top of slope. The velocity of flow between runners was opposite. This paper reveals the basic features and differences of velocity variation along the slope between the rill and the rill, and helps to understand the differences in the erosion mechanism between the rill and the rill.