上方来水对坡面降雨入渗及土壤水分再分布的影响

Effects of runoff from upslope on rainfall infiltration and soil water redistribution at a planar slope

在防止土壤侵蚀和雨后抑制蒸发的条件下,利用室内模拟降雨试验,研究了上方来水对坡面降雨入渗、湿润锋运移以及土壤水分再分布的影响。结果表明:对于初始含水量很低的土壤,与上方无来水相比,上方来水时降雨入渗过程中入渗率有一个上升的阶段,但平均入渗率反而降低;在降雨入渗初期,由于上方来水的沿程入渗,上方来水对坡面湿润锋运移的影响较大,但随后几乎没有影响,湿润锋的运移主要与基质势梯度有关;土壤水分沿坡面呈"波浪形"分布是坡面径流的波动性、上方来水(径流)的沿程入渗以及侧向沿坡向下流等综合作用的结果。

The effects of runoff from upslope on rainfall infiltration, wetting front movement and soil water redistribution are studied based on the simulated rainfall at a planar slope, while soil erosion is prevented during rainfall infiltration and evaporation is stopped during soil water redistribution. The results show that when initial soil water content is very low, the infiltration rate at hillslope with runoff from upslope has an increasing process but the average one decreases, compared with the rainfall infiltration without runoff from upslope. Runoff from upslope has a marked effect on wetting front movement at the beginning of rainfall infiltration due to upslope runoff infiltration, and then has a little effect, which implies that the wetting front movement mostly depends on the matric suction. The wave distribution of soil water along hillslope results from the fluctuation of overland flow, upslope runoff infiltration, and lateral downslope flow.