An Assessment of Digital Elevation Model for Geospatial Studies: A Case Study of Alawa Town, Niger State, Nigeria
Advanced Space borne Thermal Emission and Reflection Radiometer (ASTER GDEM), Shuttle Radar Topography Mission (SRTM), and GTOPO30 are forms of open source DEMs that are freely available for nearly the entire globe. The accuracy of these DEMs becomes very pertinent as they are fast becoming substitute for large field studies, hence, the need for assessment of known DEMs available. Therefore this study is assessied the accuracy of DEMs that were generated from three types of global data sources (SRTM, ASTER, GTOPO) and a reference DEM - topographical map (TOPODEM) to serve as control in Alawa Town of Niger State, Nigeria. Basic topographic characteristics such as hillshade, slope and topographic wetness index were analyzed, while morphometric indices such as terrain rugged index, catchment area and
channel network were analyzed using the four DEMs and explained qualitatively. The result revealed that, although with a fine representation of the area, ASTER exaggerates; SRTM was closer to the reference DEM while GTOPO30 was poor in its representation. In addition, quantitative analysis was performed using best fit on plots. This revealed that SRTM has a strong positive relationship of 95.05% with the reference DEM unlike the ASTER and GTOP30 with 94.71% and 55.19% respectively.
© Department of Geography, Obafemi Awolowo University Ile-Ife, Nigeria 2016