Assessing the accuracy of different open-source Digital Elevation Models (DEMs) in morphometric analysis of Kanchi River basin

The Kanchi river basin is located in India. The Digital Elevation Model (DEM) is an important input in morphometric analysis; however, the accuracy of DEMs has not been comprehensively assessed, particularly over the Kanchi River basin, India. Furthermore, very few studies have been conducted on newly released DEMs, e.g., NASA DEM. This study compares the vertical accuracy of publicly accessible 16 DEM products, with spatial resolutions ranging from 12 m to 90 m, using toposheet data as a reference. We also evaluate how accuracy changes with increasing elevation. Specifically, morphometric parameters calculated from these DEMs are compared, and the impact of DEM spatial resolution on these parameters is examined. Six statistical parameters (R 2 , NASH, ME, RMSE, NMSE, and PBIAS) are used to analyze DEM accuracy. We found that (1) TanDEM-X (resolution of 12 m) and the ALOS DEM (i.e., AW3D; 30 m) performed best, with low RMSE values of 8.37 m and 8.66 m, respectively; (2) DEM accuracy decreases with increasing elevation, and the accuracy of low-resolution DEMs decreases more rapidly than that of high-resolution DEMs; (3) a significant difference in morphometric parameters was observed between low- and high-resolution DEM products; and (4) due to their detailed surface elevation and high vertical accuracy, high-resolution DEMs (TanDEM-X and AW3D) provide a better and more reliable estimation of basin morphometry. • Comparison of vertical accuracy and estimated morphometric parameters using DEMs. • The vertical accuracy of higher resolution DEMs is better than coarser DEMs. • The accuracy of DEMs varies significantly with changing elevation. • Variation observed in different morphometric parameters estimated from DEMs.