长江三峡花岗岩林地坡面降雨渗流与水土流失关系研究

在大量的野外观测试验的基础上,根据土壤水分的形态和能态,对长江三峡花岗岩林地坡面降雨渗流机制进行了分析研究,研究发现在试验区当降雨强度大于表层土壤入渗率,即地表产生积水的情况下,长江三峡花岗岩林地坡面优先流在土壤含水量未达到最大毛管持水量时开始产流,早于土壤渗流产流的时间;在降雨强度小于表层土壤入渗率,即地表不产生积水的情况下,土壤渗流产流早于优先流产流;从壤中流产流过程来看,在地表不产生积水的条件下,土壤渗流先于优先流产生;在地表产生积水而土壤水分含量未达到最大毛管持水量的条件下,优先流先于土壤渗流产生。在两种情况下,优先流的峰值都先于土壤渗流。

FIELD EXPERIMENTS AND FINDINGS ON THE RELATIONSHIP OF INFILTRATION AND RUNOFF WITH RAINFALL ON FOREST GRANITIC SLOPE AT THREE GORGES OF YANGTZE RIVER

Based on the measured data in the field and according to the form and energy of soil water,the mechanism of the rainfall infiltration in the surface of the granite forestland of Three Gorges area was studied.The results showed that when the rainfall intensity was larger than soil infiltration rate and soil water did not reach the largest capillary water volume,preferential flow appeared.It appeared earlier than infiltrated soil water flow.When the rainfall intensity was smaller than soil infiltration rate,and there was no water accumulated in the surface,infiltrated soil water flow appeared earlier than preferential flow.From the flow process of infiltrated soil water,it can be seen that the infiltrated soil water flow appeared earlier than the preferential flow when there was no water accumulated in the surface,and that the preferential flow appeared earlier than the infiltrated soil water flow when there was water accumulated in the surface and the soil water did not reach the biggest capillary water volume.In both conditions,the peak of preferential flow appeared earlier than that of infiltrated soil water flow.