Abstract
In hydro-environmental simulation, DEM based stream network plays a very important role. The artificial stream network is widely used since it is essential to build a distributed hydrologic model reflecting topographic and other land surface heterogeneity. However, to increase its reliability and accuracy, some problems need to be further elaborated. One of them is the choice of drainage directionassignment rule. Among the various exiting methods, the steepest slope approach and the lowest elevation method were compared in theory and practices. It was found that the different direction assignment rules yield quite different hydrographs and that the rules need a major attention in grid DEM based hydrological study. In addition, practical ways of handling deserts, inland rivers and to enlarge DEM grid size are presented in the case of the Yellow River of China.
