Study of Extracted River System of South Zhuozhanghe Watershed by DEM

In this paper,the detailed process of the river system extracted from digital elevation model(DEM) was analyzed,and extraction of the river system of the South Zhuozhanghe watershed was done by using the data of 1:250000 DEM.The results show that the extracted river system matches well with the natural river system by means of adding the elevation data and digitizing main river with pseudo river.A new technique was developed for eliminating the pseudo river occurred in the process of extracting river system in the flat areas.