黄土坡面细沟水流流型试验研究

采用组合小区模拟降雨试验方法,对黄土坡面细沟水流流型进行了试验研究。结果表明:(1)细沟水流流型判别指标雷诺数随径流历时的变化,在不同雨强及不同坡度下皆表现为先增大随后转为较平稳的变化过程,皆可用幂函数方程描述;(2)细沟水流平均雷诺数分别随雨强及坡度增大而增大,均可用对数方程很好地描述,随雨强及坡度的变化可用二元幂函数方程描述;(3)细沟水流在不同雨强下几乎一直处于层流状态,两个最大雨强在产流开始9min后变为过渡流,而在不同坡度下也一直处于层流状态,两个最大坡度在产流开始15min后变为过渡流;(4)在试验雨强及坡度条件下,一次降雨径流过程的细沟水流平均雷诺数变化范围为327~457,表明细沟水流流型在试验条件下大致处于层流状态。细沟水流雷诺数随流量的变化呈显著的线性正相关关系。

Experimental Study of Rill Flow Pattern on Loess Hillslope

The flow patterns involved in rill erosion process on loess hillslope are studied by a multi-plot experiments under simulated rainfall with addition of steady in-flow through the tops of the plot. The results showed that: (1) The Reynolds number of rill flow, a judging index of flow pattern, changed under different rainfall intensities and slopes with a overall rise and finally a stabilized trend. A power function equation can be used to describe the two processes. (2) The average Reynolds number of slope rill flow increases with rainfall intensity and slope. Its relation to both rainfall intensity and slope can be described by a logarithmic equation; and to both of the two factors, by a dual power function equation. (3) The rill flow pattern is the laminar flow under different rainfall intensities and slopes. Only under the two of the largest rainfall intensities and slopes, rill flow may be in the transition region. (4) The average Reynolds number, a measure of fluid turbulence, varies between 327 and 457 and remains in the regime of normally considered laminar flow. The change of the Reynolds number, with the amount of the flow, is a significant positive linear correlation.