Watersheds and Drainage Networks

Abstract

Grid-based distributed hydrologic models rely on a drainage network to model basin response. A digital elevation model (DEM) is useful for characterizing the terrain and drainage network. Processing steps and DEM cell size affect the land surface slope, drainage network length and connectivity properties. Derived drainage networks and the hydraulic parameters used to represent the conveyance of runoff to the outlet of the river basin are dependent on cell size and on the methods used to derive the drainage network. Once the drainage network is defined and slope derived, the remaining hydraulic parameters are applied to overland and channel cells, which may require adjustment. The characteristics of the extracted drainage network can influence hydrologic model calibration and performance.