Estimation of vertical accuracy of Digital Elevation Models over complex terrains of Indian subcontinent

摘要

Complex terrains (mountains) of varying elevations cover approximately 25% of the total global land area wherein nearly 26% of the world's population resides. Complex terrains offer difficulty in accurate owing to their inaccessibility and location constraint to carry out ground based survey. Digital Elevation Model (DEM) offers a reliable alternative to study the orography from remote sensing measurements. Mountainous surfaces and dense vegetation covers offer large DEM errors as compared to flat terrains owing to the terrain characteristics. The reliability of DEMs for watershed modeling is often hinged on their vertical accuracies. In the present study, the vertical accuracies of three DEM from three sources namely, Shuttle Radar Topography Mission (SRTM), Advanced Spaceborne Thermal Emission and Reflectance Radiometer (ASTER) and CARTOSAT are examined over the complex terrains of the Indian subcontinent. The spatial variability using geostatistics is assessed over 440 triangulated benchmark stations procured from the Survey of India Department toposheets. It is observed that the RMS error for SRTM DEM is less as compared to the other sources. The value of mean error increases continuously with the rise in the elevation showing the effect of terrain morphology on the accuracy of the DEM. The mean error for ASTER, SRTM and Cartosat is 42.75 m, 36.84 m and 37 m respectively. SRTM DEM shows better results for the morphometric analysis by generating large drainage networks over Upper Bhima Basin. For the future these results can be highly useful in various hydrological modeling over the different river basins.