Evaluation of Sentinel 1-derived and open-access digital elevation model products in mountainous areas of Western Ghats, India

Digital elevation model, acquired and generated using manual field survey, stereo pairs, interferometric synthetic aperture radar (InSAR) and light detection and ranging techniques to characterize terrain topography, plays a dynamic role in geological and hydrological applications. Digital elevation models (DEMs) are subjected to comprise ineradicable faults owing to acquirement techniques and pre-processing methodologies. Experiencing non-uniform variation in accuracy, it is mandatory to assess the accuracy of DEMs before employing it for numerous purposes. Considering the fact, assessment of vertical and horizontal accuracies of open-access DEMs and InSAR-derived DEM is performed with Survey of India (SOI) toposheets as reference. Results concluded that Cartosat DEM and SRTM DEM of 30 m resolution with NRMSE as 10.5% and 10%, respectively, and PBIAS as - 0.3% and - 0.5% respectively highly correlated with the toposheet elevation when compared with other DEMs. Horizontal assessment of pixel offset concluded that Cartosat and SRTM DEM experience an offset of 0.1% along X-axis and 0.33% along Y-axis. Assessment of vertical accuracy and pixel offset concluded that CartoDEM and SRTM DEM are highly recommended for research purposes over Kodagu District, Karnataka, India. InSAR-derived DEM experiences massive variation and are not suggested over hilly terrains.