流域水系自动提取在西苕溪流域的应用

THE APPLICATION OF AUTOMATICALLY EXTRACTING STREAM NETWORKS IN THE XITIAOXI WATERSHED

论述了如何基于栅格DEM自动提取流域自然水系的原理、方法和流程。以西苕溪中上游流域为例,根据DEM精度、上游集水区面积阈值和下垫面地形的不同,对所提取水系进行了比较。针对在平均地形坡度小于3°的平坦区域所提取水系与实际河网偏差较大的问题,提出了利用主干河道和平原水系数字化作为约束条件生成河网的新方法。

The principles, methods and process of automated extraction of natural stream networks of watershed based on raster DEM are described . The middle and upper reaches of the Xitiaoxi watershed are taken as a case of study. Through comparing the stream networks delineated from different resolution DEMs, threshold values of high flow accumulation and terrains, the combination of DEM resolution and the threshold values suited to this area are obtained. By comparing the stream networks delineated from DEM with the actual stream networks, it can be concluded that in the mountain area, especially the area of mean slope not less than 3 degrees, the delineated stream networks are much reliable. In the flat region of mean slope less than 3 degrees, the delineated stream networks are much different from the actual ones. In order to solve the problem, the restricted river channel method by digitizing the trunk streams and the rivers on flat land is put forward. With the method, the delineated steam networks are in accordance with the actual ones. It makes the simulation of hydrologic factors more practical.