Sensitivity of topographic slope and modelled watershed soil loss to DEM resolution

摘要

A Digital Elevation Model (DEM) is a critical component for the parameterization of process-based watershed simulation models. The influence of DEM resolution on hydrological or water quality outputs is frequently ignored within watershed modelling studies. This research focuses on the effects of varying spatial DEM resolutions on the determination of slope and how this can influence sediment yield estimates within a process-based watershed model. The 784-ha Thomas Brook watershed in Nova Scotia, Canada was used as a case study. The grid spacing of a LiDAR derived DEM was created at 1, 5, 10 and 20 m and used to generate slope maps and predicted sediment loss with the Soil and Water Assessment Tool (SWAT). It was found that the occurrence of steep slopes increased in fine spatial resolution DEMs while predicted sediment loss decreased.