Automated extraction of drainage networks from digital elevation models

Abstract

The use of grid-based Digital Elevation Models for the automated extraction of drainege networds in three experimental watersheds is presented. Simple algorithms are applied to simulate water flow over basin's surface, based on the assumptions that water runoff is controlled by gravitational forces and is homogeneously generated throughout the basin. For these porposes, it is first necessary to ensure the hydrological connectivity of the DEM, what is solved in this study by the application of local mean filters in those cells where flow direction is not defined. A new internal validation method for the determination of the range of scales over which the results of the analysis are really correspondent to the basin's geomorphology is proposed. The obtained results are found to be, in the appropriate range of scales, coincident with field observations, and with the advantages of higher precision and lower costs than manual procedures commonly used for drainage network delineation.