基于DEM的数字河网生成方法的探讨

Method for extracting digital channel network from digital elevation model of watershed

流域地形是决定河网水系的一个关键性因素,是数字流域和分布式水文模型研究的主要内容。总结了根据流域的数字高程模型(DEM)自动提取河网水系的集水面积方法。首先计算出流域上各点(或栅格)的集水面积;然后通过分析临界支撑面积(CSA)的取值对所提取的数字水系总长度以及平均坡降的影响,确定反映该流域河流地貌发育的临界支撑面积。并选择一个面积为265km2的流域进行了河网水系提取的实例分析,所得结果和实际情况比较符合。该方法自动化程度高,在分析流域的河网水系结构特征时具有一定的应用价值。

The watershed topography is a key factor in the formation of the channel network and thus becomes a very important topic in the study of the digital basin and the distributed rainfall?runoff models. The widely used method for extracting the watershed channel network from digital elevation model (DEM), i.e. the water catchment area method, is presented. This method includes two steps: calculation of the water catchment area for each pixel of DEM, and determination of the critical support area (CSA) for channel development by analysis of the effects of the critical support area on both the total length and the average slope of the extracted channel network. The water catchment area method is employed to extract the channel network of a medium?size watershed with an area of 265 km2, and the extracted results are reasonably close to the reality. Because this method is automatically executed, it can be very useful in the analysis of the characteristics of the river networks of watersheds, especially for those uncharted regions.