长江三峡花岗岩坡面管流在壤中流中的作用

 大孔隙中运动的水流称为管流,管流是优先流的一种形式。在花岗岩地区,管流是一种普遍现象。为研究管流在壤中流中的作用,在长江三峡花岗岩坡面 ,选择了受人为活动影响较小的天然次生马尾松林地作为试验场地,研究长江三峡花岗岩坡面管流过程和土壤渗流过程。结果表明:管流的出现较渗流出现时间迟 ,但其结束的时间较渗流早。管流与渗流峰值出现时间存在一定差异,在所研究的2场降雨中,管流达到峰值的时间比渗流提前约1～2h以上。同渗流一样 ,管流流量及其过程,主要受由降雨引起的下渗水分影响和制约,管流流量的大小变化,与渗流存在一定差异,但总体上,与渗流流量的变化趋势一致 ,即在管流产流时段,渗流流量增大时,管流流量也随之增大。管流水分通量远大于渗流的水分通量,它对于提高壤中流流量和水分通量,具有促进作用。在不同降雨过程中,管流对壤中流的作用也存在差异,即降雨量越多,降雨强度越大,管流的特性表现得越明显,对壤中流的贡献也越大。

Effect of pipe flow on interflow on granite slope in Three Gorges area of Yangtze River

Water flowing in macropores is called pipe flow, and it is one kind of preferential flow. Pipe flow is common in the granite region. For studying the effect of pipe flow on interflow, a natural second Pinus massoniana woodland which is not heavily influenced by people in the granite region of Three Gorges of Yangtze River was selected as a field site. The process of pipe flow, infiltration and the rainfall is recorded respectively. The results show that pipe flow starts after the infiltration and ends before the infiltration. The peak value of infiltration flow and pipe flow does not appear at the same time. The appearance of the peak value of pipe flow is more than 1～2 hours earlier than that of infiltration in the process of the two rainfalls which have been studied. Just as infiltration, pipe flow is mainly influenced by infiltration water caused by the rainfall. There is certain difference between the discharge change of pipe flow and infiltration. But the discharge of pipe flow accords with the trend of the discharge of infiltration. The discharge of pipe flow will increase while that of infiltration increase during the period that pipe flow produces. The flux of pipe flow is greater than that of infiltration and it can increase the discharge and flux of interflow. The effect of pipe flow on interflow is different according to different rainfall processes. As rainfall amount is larger and rainfall density is higher, the characteristic of pipe flow is more obvious and the effect on interflow is greater.