An intensifying method for extracting drainage networks in a plain with violent human activities

The distributed hydrological model is an essential tool to simulate rain-runoff processses over plains in North China for solving the problem of water shortages. The extraction of drainage networks from digital elevation model(DEM)is a basic work to build the distributed hydrological model in a watershed. Many commonly used methods do not work properly when extracting drainage networks in flat areas with violent human activities. Two reasons for this situation are: the elevation of every DEM cell in this area is nearly the same so it is difficult to determine the flow direction; many man-made canals would disturb the flow direction. This paper puts forward an intensifying method to pre-treat DEM cells of the main stream. By using the proposed method, a topological structure of water system with more detailed and accurate river networks can be derived for dividing the hydrological response units in modeling. The result fits well with the natural stream networks, showing that the proposed method is a convenient, quick and easy method to solve the drainage network extraction problem in flat plains with violent human activities.