Comparison and Validation of Satellite-Derived Digital Surface/Elevation Models over India

India presents among the world's most topographically complex geomorphologies, with land elevations ranging from -2 m to + 8586 m and terrain gradients sometimes exceeding 45 degrees. Here, we present an evaluation of four freely available digital surface models (DSMs) on a model-to-model basis, as well as a validation using independent ground-truth data from levelled benchmarks in India. The DSMs tested comprise SRTM1 '', SRTM3 '', ASTER1 '' and Cartodem1 '' [an India-only model]. Along with these four DSMs, the MERIT3 '' digital elevation model (DEM) is also tested with the ground-truth data. Our results for India indicate some mismatch of these DEMs/DSMs from their claimed accuracies/precisions. All DSMs/DEMs (except for ASTER) have > 90% of pixels satisfying +/- 16 m at the one-sigma level, but only in the low-lying (< 500 m) parts of India, i.e. the Gangetic plains and the Thar desert.