Effects of DEM sources on hydrologic applications

Digital elevation model (DEM) data have been used to derive hydrological features which serve as inputs to various models. Currently, elevation data are available from several major sources and at different spatial resolutions: the National Elevation Dataset (NED), Shuttle Radar Topography Mission (SRTM) data, and the Light Detection and Ranging (LIDAR) data. This article shows the variability of analysis results from these data sources and of different scales. A standard algorithm in GIS was used to extract river networks from these DEM data for part of Kansas. Extracted networks were compared with the one derived from the National Hydrography Dataset (NHD). Flood simulation results obtained from various sets of DEM data were also compared. Using higher resolution DEMs can derive more accurate river networks, but highest resolution data may not necessarily offer the best results, depending on the resolutions selected to compare the extracted networks. DEM spatial resolution may have minor impacts on flood simulation results, but inundation areas from flood simulations vary significantly across different DEM data sources. Results highlight the caveats on using DEM-derived river network data for hydrologic applications and the difficulties in reconciling differences among elevation data from various sources and of different resolutions.