侵蚀性风化花岗岩坡地降雨产流及水文过程研究

Characteristics of Rainfall Runoff and Hydrological Dynamics on the Erosive Weathered Granite Slope

为研究坡地的降雨产流分配及水文动态过程,以侵蚀性风化花岗岩坡地为研究对象,采用室内人工模拟降雨的方法研究不同降雨强度(30,60,90,120,150mm/h)和不同坡度(5°,8°,15°,25°)条件下坡面径流和壤中流的分配特征与水文过程。结果表明:坡面径流的初始产流时刻均随降雨强度和坡度的增大而提前,壤中流的初始产流时刻明显滞后于坡面径流。壤中流径流量在不同坡度下随降雨时间的延长呈先递增后趋于平稳的现象,雨强越大达到峰值的时间越早,在降雨停止一段时间后径流量开始下降。多数情况下,壤中流所占总径流量的比重均大于坡面径流,坡面径流量比重随雨强的增大而增大,随坡度的变化幅度较小。坡面径流的径流系数与雨强的相关性较强,而壤中流径流系数与坡度之间的拟合效果较好。不同坡度下坡面径流、壤中流和混合流(坡面径流与壤中流同时发生)的径流模数与雨强呈正相关关系,不同类型径流的径流模数大小依次为混合流>壤中流>坡面径流。

To study the characteristics and hydrological dynamics of rainfall runoff on sloping land,the overland flow and subsurface flow on the weathering granite sloping land at different rainfall intensities（30,60,90,120,150 mm/h）and slope gradients（5°,8°,15°,25°）were comparatively studied with the method of artificial simulated rainfall.The results showed that the initial starting time of both the overland flow and subsurface flow advanced with the increase of rainfall intensity and slope gradient.The initial starting time of subsurface flow obviously lagged behind that of overland flow.With extension of rainfall time,the subsurface flow rate at different slope gradients turned to be stable after an increasing trend.The greater the rainfall intensity was,the earlier the subsurface flow rate reached the peak.And subsurface flow rate began to run down after the rainfall stopped for some time.In most cases,the proportion of subsurface flow was larger than that of the overland flow.The proportion of overland flow increased with the growth of rainfall intensity.Slope gradient,however,had little influence on the proportion of overland flow.The runoff correlation between the overland flow and rainfall intensity was relatively large,and the runoff coefficient of subsurface flow was mainly affected by slope gradient.The runoff modulus of overland flow,subsurface flow and mixed flow（overland flow and subsurface flow occurred simultaneously）showed a strong positive correlation with rainfall intensity and displayed the following order：mixed flow〉subsurface flow〉overland flow.