土壤初始含水率对坡面降雨入渗及土壤水分再分布的影响

在防止土壤侵蚀和雨后抑制蒸发的条件下，利用室内人工降雨试验，研究了土壤初始含水率对坡面降雨入渗、湿润锋运移及土壤水分再分布规律的影响。结果表明：初始含水率越高，产流越快，平均入渗率越小，达到稳定入渗率的时间也越短；当初始含水率均匀分布时，降雨入渗和再分布过程中湿润锋面平行坡面垂直向下整体运移，坡面降雨入渗过程可以简化为一维；当初始含水率非均匀分布时，初始含水率越高，再分布过程中湿润锋的运移速率越大，但在降雨入渗过程中，湿润锋的运移速率与土体的湿润程度和范围有一定的关系；坡面上方来水(径流)虽然对湿润锋运移速率影响不大，但对入渗有一定的促进作用；再分布过程中，土壤水分有沿坡向下运移的趋势。

Effects of initial water content on hillslope rainfall infiltration and soil water redistribution

Under preventing soil erosion and controlling evaporation after rainfall, the effects of initial water content on hillslope rainfall infiltration, wetting front movement and soil water redistribution were studied with simulated rainfall. The results show that when initial water content is higher, runoff generation is earlier, average infiltration rate is smaller, and the time to be stable infiltration rate is shorter. Rainfall infiltration into a planar hillslope with homogeneous isotropic soil could be simply regarded as one-dimensional infiltration process, and wetting front is nearly parallel to the soil surface and moves down vertically during rainfall infiltration and soil water redistribution, when the distribution of initial water content is uniform. Wetting front moves faster with higher initial water content during soil water redistribution, but its movement depends on the wetted degree and scope of soil during rainfall infiltration, when the distribution of initial water content is non-uniform. Runoff from upslope has little effect on wetting front movement but helps to increase infiltration. Moreover, soil water would move downslope after rainfall infiltration was terminative.