Vertical accuracy evaluation free access digital elevation models (DEMs): case Fergana Valley in Uzbekistan

In this study, the vertical accuracy of Shuttle Radar Topography Mission Digital Elevation Model Version 2.0 (SRTM30), Advanced Spaceborne Thermal Emission and Reflection Radiometer Global DEM (ASTER GDEM2), Land Observing Satellite World 3D Surface 2.1 (ALOS AW3D30) was statistically assessed using GPS data. The Fergana Valley area chosen as a study region, where land surface can reflect tectonic processes. values ellipsoidal heights 27 points regional network were reference geometric approach GPS/leveling data EGM96 global geopotential model-based geoid undulations applied for fitting. height corrections range ranged from –0.66 m to 0.87 m. Root-Mean-Square errors ~10.0 m, ~16.4 ~6.6 obtained SRTM30, ASTER GDEM2, ALOS AW3D30, respectively. It found that compared with model, all DEMs in mountainous areas generally overestimated elevation value at 90% confidence level by 3-6 meters exceeded declared distributors. But AW3D30 proved be most accurate best represents topography earth’s could used some engineering applications Valley.