Impact of DEM resolution and accuracy on remote sensing and topographic DEM derived topographic attributes and drainage pattern

Abstract

Digital Elevation Model (DEM) presents the digital representation of surface topography. DEMs can be derived from satellite remote sensing or conventional techniques of surveying. However, inherent errors in a remote sensing based DEMs can lead to uncertainty in the elevation data and computed topographic attributes. This study evaluates accuracy of remote sensing derived SRTM and ASTER DEMs and physical survey derived Topographic maps. For accuracy assessment of the ASTER and SRTM ASTER DEMs, spot elevation were extracted from the toposheet as a reference data. Accuracy assessment results reveals that the SRTM DEM shows RMSE of ±27 m and ASTER DEM shows RMSE of ±20 m in the study area. The impact of random errors in the ASTER and SRTM DEMs on the derived topographic attributes (aspect and slope) is evaluated through the Monte Carlo Simulation (MCS). Derived results show higher uncertainty in topographical attributes (aspect and slope) derived from the ASTER DEM than from the SRTM DEM. Results derived from the ASTER DEM shows that mean of slope can deviate 1.2° whereas, SRTM DEM shows it can deviate 0.8°. Aspect derived from the ASTER DEM can deviate up to 31.2° whereas, aspect computed from the SRTM DEM can deviate up to 29.8°. The drainage networks computed from the ASTER, SRTM DEMs and Toposheet are also compared. The analysis revealed that the drainage network extracted from the SRTM DEM, ASTER DEM and Toposheet are matching.