基于DEM的流域流水网对比分析

Comparative analysis of drainage networks derived from grid-based DEM

在广东西江中下游区间流域和长江三峡区间流域上 ,运用ARC/INFO和RiverTools ,由数字高程模型 (DEM )分别导出了不同空间比例尺下的流域流水网 .对比分析结果表明 :地形起伏大的流域上流水网的可靠性高 ;不同方法推导出的流水网存在一定的差异 ,尤其在地形起伏较小的流域上 ;由流水网计算的流域平均汇流路径长度和坡度等地形特征值随DEM网格的大小而变 ,故只能作为描述地形的相对指标 .上述指标可应用于流域水文模拟中 ,但应用时需考虑地形的起伏程度和DEM网格的大小 .

Drainage networks for the Three Gorges interbasin area and the middle and lower reaches of the Xijiang River Basin of Guangdong Province are derived by use of ARC/INFO and RiverTools based on the digital elevation models (DEMs) of different scales. Comparative analysis shows that the reliability of the drainage networks is high for the river basin with large undulation of topography, and that some differences exist between the drainage networks derived with different methods, especially in the river basin with small undulation of topography. Some topographic indexes derived according to the drainage networks, such as the mean length of flow concentration routes and the mean gradient of hill slopes, vary with the grid-size of the DEM, so they can only be used as relative indexes. The above indexes can be used for hydrological modeling of river basins, but the undulation of topography and the grid-size of the DEMs should be taken into account in practical application.