The use of digital elevation models in the identification and characterization of catchments over different grid scales

Abstract

This study examines the ability of well-known hydrological and geomorphological descriptors and statistics to differentiate between catchments with spatially varying geology, size and shape subject to the same climate in the Northern Territory, Australia. The effect of digital elevation model grid resolution on these statistics is also examined. Results demonstrate that catchment descriptors such as the area–slope relationship, cumulative area distribution and hypsometric curve can differentiate between catchments with different geology and resultant morphology, but catchment network statistics are insensitive to differences in geology. Examination of the effects of digital elevation model grid scale demonstrates that while considerable catchment information can be gained at digital elevation grids greater than 10 m by 10 m, hillslope and hydrological detail can be lost. Geomorphic descriptors such as the area– slope relationship, cumulative area distribution, width function and Strahler statistics were shown to be sensitive to digital elevation model grid scale, but the hypsometric curve was not. Consequently, caution is needed when deciding on an appropriate grid resolution as well as the interpretation and analysis of catchment properties at grid scales greater than that for optimal hillslope and area aggregation definition. Copyright  2005 John Wiley & Sons, Ltd.