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| Effect of pipe flow on interflow on granite slope in Three Gorges area of Yangtze River |
| Zhang Hongjiang 1, He Fan 1, Shi Yuhu 2, Qi Shenglin 1, Cheng Jinhua 1, Pan Lei 2 |
| 1.Beijing Forestry University, 100083, Beijing; 2.Forestry Academy of Hubei Province, 430075, Wuhan: China |
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Abstract 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.
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Received: 31 March 2004
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