山坡地形曲率分布特征及其水文效应分析——真实流域的野外实验及相关分析研究

Distribution charateristics of hillslope curvature and its effects on hydological processes:A real-world test

研究了山坡地形曲率的空间分布特征,发现流域略呈现出微凹、发散的形状特征,平均的剖面和水平曲率分别为-4.62×10-4和3.49×10-4。通过划分源头型和边坡型山坡,发现源头山坡多是收敛的,边坡型山坡则多为发散的;在山坡内部收敛、发散、凹和凸等地形地貌类型是同时存在的,即山坡一般由相互组合的各种坡型所组成。基于野外采样观测的成果,分析了和睦桥子流域90个采样点的土壤含水量及其对应曲率的相互关系。结果显示:一般来说,凹形山坡、收敛形山坡对应的土壤含水量更高,而凸形和发散形山坡对应的土壤含水量较低;不论是收敛的凹坡,还是发散的凸坡,其采样点土壤含水量都有随高程下降而升高的趋势,即愈靠近沟谷土壤含水量愈大。

Hillslope curvature includes the characters e. g. divergent/convergent and convex/concave etc. These characters are second-order topographic parameters contrasted to slope and length of hillslope. In this study, a 10 m x× 10 m DEM dataset was created using the 1 ： 10000 elevation contour maps for the Jiangwan catchment of Tiaoxi River, on the Taihu basin. The curvature distribution within hillslopes can thus be studied. The averaged profile and plan curvature for the catchment are found to be -4.62×10^-4 and 3.49 ×10 ^-4, respectively, indicating the catchment is overall convergent and divergent. Through dividing of the catchment into two types of hillslopes headwater and side- slope, we find that the headwater hilMope is generally convergent, while the sideslope hillslope tends to be more divergent. Divergent, convergent, convex and concave are coexisting within an individual hillslope. A total of ninety soil moisture samples were taken from the Hemuqiao sub-catchment. Soil moisture contents and corresponding curvatures were analyzed. It is shown that the concave or convergent hilMopes are always with higher soil moisture values, while convex or divergent hillslopes with lower ones. Soil moisture contents decline with the increase of elevations.