摘要
本文在研究降雨时空分布不均匀与下垫面自然地理参数空间分布不均匀，对降雨径流过程影响的基础上，提出了一种在地理信息系统支持下的动态分布式降雨径流流域模型，实现了基于栅格的坡面产汇流与河道汇流的数值模拟，能够获得流域上任意模拟时刻任意栅格的径流量。模型视栅格为水文一致性单元，水文参数在栅格内一致，在相邻栅格间变化。采用Ｈｏｌｔａｎ模型计算下渗率，水量平衡方程和线性水库的马斯京根法进行栅格产汇流演算，模型的每个参数具有明确的物理意义和地理规律，本文的产汇流模拟方法以石桥铺径流实验区作为验证，取得较好效果。
After having studied the precipitation-runoff process affected by the spatial and temporal variability of precipitation and the spatial differences of physi-geographic parameters on the earth's surface, this paper developed a dynamic model based on grid data. The model takes topographic map.soil distribution map. land use map. precipitation. evaporation. seepage and moisture content of soils as inputs. The hydrological grid data base is supported by the Geographic Information System (GIS). XMGIS 2. 0, which is made by the authors. According to the model, necessary analyses of digital topographic model and grid superposition are made, and the grid element assigned grade and flow forms a fully watershed (Fig. 2).When the runoff yield and the inflow of surface and subsurface. taking the grid element as a unit . are respectively calculated. the outflow of a grid element is one of inflows in the corresponding subgrid. All the grid element is continuously calculated in the order of grade , and the flow process in every time interval is finally obtained.The modle takes the grid element as a hydrologically homogeneous unit. Hydrological parameters and physi-geographic characteristics are assumed to be uniformly distributed in each grid element. but vary between elements. Holtan model is used for infihration rate:The infiltration rate to deep soil layers is:where f is the capacity of infiltration. Fc is the actual infiltration rate in the soil profile. GI is the grain-growing index. a is the cover index. n is the parameter of soil structure, Sa is the maxmum volume lack of water is the soil profile. fc is the stable infiltration rate.Water-balance equation and modified Muskingum method are used for routing runoff yield and inflow from adjacent relevant grids.The water balance equation based on grid element is:where i is the number of grid element. 1 and 2 the beginning and the end of time interval, COQ and COGW are the volume of surface and subsurface inflows from adjacent grid elements respectively, E is the total evaporation on the surface of water in a time interval, F is the surface infiltration rate ,S is the volume of surface water-bearing. W is the water content of soil layer. △t is the length of time segment, P is the rainfall in a time interval, Q and GW are the surface and subsurface outflow respectively in a given grid element. and is EW the soil evaporation.The Muskingum flow equation is:Where k is the coefficient of surface water-bearing, kg is the coefficient of subsurface water-bearing and discharge, I is the total input of surface water in a time segment, GI is the total groundwater input of a grid element in a time interval.In the model, every parameter has specified physical meanings and geographically distributed characteristics. The simulation method was proved effective by examing Shiqiaopu runoff experiment basin (Fig. 5).
出处
《地理学报》
CSSCI
CSCD
北大核心
1995年第3期264-271,共8页
Acta Geographica Sinica
基金
国家自然科学基金
国家教委博士点基金
关键词
流域
降水
径流模型
栅格数据
Geographic Information System (GIS), dynamic runoff precipitation watershed model, grid element. Holtan Model, Muskingum method
