小流域产流产沙动力学模型

A Dynamic Model of Runoff and Sediment Yield from Small Watershed

按自然水系划分单元,每一单元又被概化为“一本打开的书”,概化后的单元又区分为几个微地貌区.各单元水沙过程演算至流域出口迭加得流域产流产沙过程.此法一方面解决了降雨、侵蚀和下垫面的不均匀性,另一方面又解决了水沙的演算问题.坡面和沟道水流用运动波方程描述并用四点隐式差分格式求其数值解.根据水流作功和能量平衡原理推导出各微地貌区上的土壤侵蚀量计算公式,建立起具有物理过程基础的小流域产流产沙模型.参数用黄土区小流域实测水沙资料率定,模型在该地区若干流域上应用,取得满意的结果.本模型成因性强,结构与参数物理概念清楚,其最大特点是能够模拟水流泥沙的时空变化过程.

The watershed under study is divided into several element watersheds according to natural drainage systems in this paper. Each subwatershed is further divided into three parts based on the vertical distribution of the soil erosion and the topography-geomorphy. All subwatersheds are schematized as a 'open book' which is composed of sloping lands with different slopes and one channel. The kinematic wave theory and the finite-difference method are used to simulate the overland flow and the river flow. The calculation formulas of the soil erosion are deduced by means of the principle of power done by flow and energy balance, and a model based on physical processes of runoff and sediment is further established. The runoff and sediment yield at the total outlet section of the watershed can be obtained by summing up the runoff and sediment yield from every subwatershed which has been routed from its outlet to total outlet respectively. The parameters of the model have been calibrated with measurement data of the catchment and the results are satisfactory. The model can be used to simulate the runoff and sediment processes in time and space.