基于人工降雨模拟试验的坡面水文连通性

为揭示降水入渗时坡面水文连通性特征以及坡度和雨强等对水文连通性的影响，研究基于人工降雨模拟试验，分别采用结构性指标径流长度（Flowlength，l_F）和功能性指标相对地表连接函数（Relative Surface Connection Function， F_RC）分析不同坡度坡面（5°、15°、25°；面积为150 cm×50 cm）在不同雨强（25 mm/h、50 mm/h、70 mm/h和86 mm/h）条件下的水文连通性。研究结果表明:坡面水文连通结构主要由l_F为0~100 mm的径流路径组成，其栅格频率高达90%以上，而l_F为100~500 mm的栅格频率为3%~8%。水文连通性的迅速发展主要集中在降水事件的开始阶段，而一定阶段以后入渗速率与地表储水速率基本持平，水文连通性呈现出较为稳定的发展趋势。坡度增大整体上有利于水文连通性的发展。5°坡面对应水文连通面积比率整体小于其他坡度。由于雨强增大到一定范围时将增加地表糙率，从而阻碍水文连通性的发展，研究中仅25 mm/h对应水文连通性明显区别于其他雨强，而其他雨强间则在多数情况下水文连通性差别较小。

Analyzing hydrological connectivity for a slope-surface on the basis of rainfall simulation experiment

Hydrological connectivity provids a possible way forward to underestand runoff process and mechnisam, which is valuable for soil erosil controling and sustainable watershed management. The research aims to characterize the slope hydrological connectivity when acconuting for infiltration process, and to investigate the impacts of both slope and rainfall intensity on hydrological connectivity development. On the basis of rainfall simulation experiment, we analyzed hydrological connectivity of a simulated slope (size: 150cm×50cm) with various degree (5°,15°, and 25°) and rainfall intensities (25mm/h, 50mm/h, 70mm/h, and 86mm/h) by using a structural indicator (Flowlength,l_F) and a functional indicator (relative surface connection function, F_RC), respectively. The results suggested that hydrological connection of the surface is mainly composed of short flow paths, l_F of 0-100 mm accounting for as high as 90%, whilst l_F of 100-500 mm accounting for 3% to 8%. The development of hydrological connectivity is mainly confined to the initial stage of the events, whilst it is difficult to further develop once the infiltration rate is equal to the surface storage rate, and the ratio of surface connected is stablized at a certain range value in the late stage. The increase in slope generally facilitate the development of hydrological connectivity. The ratio of surface connected on 5 degree-slope is generally lower than the others. Due to the increase in surface roughness, the development of hydrological connectivity is limited when the rainfall intensity is increased to a certain degree, which partly explain the insignificant change in hydrological connectivity under the rainfall intensity of between 50 mm/h, 70 mm/h, and 86 mm/h.