Building channel networks for flat regions in digital elevation models

Abstract Digital elevation models (DEMs) are data sources for distributed rainfall–runoff modelling in terms of providing the channel network for a watershed of interest. Assigning flow directions over flat regions is an important issue in the field of DEM processing and extraction of drainage features. Existing methods cannot fully incorporate the information of known drainage features and terrain surrounding the flat region. This study presented a hydrological correction method that integrates topographic information from different sources to interpolate a convergent surface. It employs radial basis function interpolation to determine elevation increment at every position, utilizes data of digital channel network, incorporates elevation in the surrounding terrain, and ensures a convergent channel network while minimizing the impact of correction on the original DEM. The method can be easily implemented in geographic information system (GIS) environment. It was applied to the DEM of the Heshui Watershed, China. The extracted channel network was visually inspected and quantitatively assessed through analysing the flow direction raster. Results showed that the channel network generated by the hydrological correction was consistent with the known drainage features and contained less parallel channels comparing with the results from two existing methods. Copyright © 2009 John Wiley & Sons, Ltd.