数字高程模型在新安江模型中的应用研究

Application of Digital Elevation Model in Xin'anjiang Model

在新安江模型中,通常利用泰森多边形法将流域分成许多单元,考虑降雨的空间分布.在所有单元中,采用相同的汇流参数.模型没有考虑地形分布的影响.流域汇流特性在很大程度上取决于地形条件.本文中利用数字高程模型(DEM)划分子流域,提取各单元的坡度及其沿河道到达流域出口的距离.建立汇流参数与地形坡度间的定量关系,使新安江模型能够考虑地形的空间分布.在沿渡河流域的应用结果表明:在30次洪水中,有效系数大于0.9的洪水次数由20%增加为46.67%;洪峰相对误差小于10%的洪水次数由40%增加为76.67%.

Generally, in Xin＇anjiang model, the basin is divided into a set of sub-basins by Thiessen method so that the spatial distribution of rainfall can be taken account, which the same recession constants of runoff concentration are used in all sub-basins. It can be seen that topography is not taken account. However, it is well known that the runoff concentration behaviors of a basin is largely depend on topographic characteristic. A new method is proposed using digital elevation model（DEM） to divide sub-basins and to derive average slope and alongchannel length of sub-basins to basin outlet. The quantitative relation between runoff concentration parameters and slope is established, which the spatial distribution not only of rainfall, but also of topography can be taken account in Xin＇anjiang model. The application results in Yandu river basin show that the number of floods with effective coefficient of bigger than 0.9 increased to 46.67% from 20% and that with relative error of peak of less than 10% increased to 76.67% from 40% in 30 floods.