Research on the Division of River Sub-drainage Slope Based on DEM

The methods of extracting drainage network and sub-drainage based on geographic information system (GIS) have been studied and applied widely. However, sometimes the charcteristcs of underlying within a sub-drainage area are different, and there are interactions between the areas with different underlying characteristcs. In traditional method, these interactions are neglected. Aiming at this problem, a new method is present in this paper to divide sub-drainage slopes of river basin into different sub-drainage units. The method is on the basis of the analysis of flow direction matrix and river network extraction. The relationship of river girds and non-river grids is analyzed. Division of sub-drainage slopes will be a useful tool for researches of physical process on the hill slopes, and supply technique support of water environmental simulation and pollution control in river basin management.