长江三峡花岗岩地区降雨因子对优先流的影响

Influence of rainfall factors on preferential flow in the granite region of the Three Gorges of the Yangtze River

为研究降雨对优先流的影响,在长江三峡花岗岩地区,选择了一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。采用自记流量计记录了优先流过程,同时对降雨过程进行测定。降雨过程中分别测定了降雨总量、降雨历时、前期降雨、>20mm/h降雨量及最大降雨强度5个因子,优先流过程中测定了优先流流量、历时、对降雨响应的滞后时间、峰值流量4个因子。分析结果表明,降雨对优先流的制约关系十分明显。影响优先流流量的主要是降雨总量,影响优先流历时的主要是降雨历时和降雨总量,影响优先流峰值流量的主要是降雨总量。采用强迫引入法,建立了优先流因子与降雨因子回归方程。

To study the influence of rainfall on preferential flow, a natural second Chinese pine (Pinus massoniana) forest in the granite region of the Three Gorges of the Yangtze River, which has not been greatly influenced by people, was selected as an experiment site. The process of preferential flow was recorded by an automatic flowmeter. The process of rainfall was recorded at the same time. The five factors of rainfall, including rainfall amount, rainfall duration, ante-precipitation, rainfall amount whose intensity exceeds 20 mm/h and peak values of rainfall intensity, were measured. The four factors of preferential flow, such as preferential flow amount, preferential flow duration, delay time to rainfall, peak values of preferential flow, were measured. The results showed that the influence of rainfall on preferential flow was obvious. For discharge of preferential flow, the decisive factor was rainfall amount. For duration of preferential flow, the decisive factors were rainfall duration and rainfall amount. For peak value of preferential flow, the decisive factor was rainfall amount. Valid regression equations were formulated between the factors of preferential flow and rainfall.