Comparison of different digital elevation models for drainage morphometric parameters: a case study from South India

With a plethora of digital elevation models (DEM) available for elevation extraction and catchment morphometric analysis, it is essential to compare and investigate their accuracy and parameter uncertainty derived from them. To serve that purpose, in this study, we have compared the DEMs of different resolution obtained from Shuttle Radar Topography Mission (SRTM), CARTOSAT, and topographic maps (1:25000) in terms of vertical accuracy and morphometric parameters. The investigation was performed on a sub-basin of Champavathi River which is located in Andhra Pradesh, the southern part of India. The vertical accuracy of the DEMs was estimated using elevation from about 1180 points obtained from the Differential Global Positioning System (DGPS) survey. The morphometric analysis showed that the basin is elongated with low relief ratio, mild/rolling slopes, and medium drainage density, and the results were comparable from different DEM sources indicating that most of the morphometric parameters were not significantly dependent on the scale and source of the DEM. Further, vertical accuracy estimation showed that the CARTOSAT DEMs (10 m and 30 m) have a lower root mean square error (4.53 m and 5.89 m) when compared with the SRTM DEMs (6.11 m and 7.19 m).