Abstract
Nowadays there are a lot of geospatial datasets available in the form of different types of Digital Elevation Models (DEMs) which were launched with different resolutions. These datasets are used for studying the physiographical features of the hydrographic basins through the tracing and extracting the elevation points, watershed boundaries, streamlines, flow directions and morphometric parameters assessment. Many researchers have used these datasets to study and evaluate the hydrologic behavior of the basins which is considered as the reflection of physiographic features of the hydrographic basins. In the Middle East especially in Saudi Arabia, the trend of using DEMs increased for hydrographic basin analysis and assessment of hydrologic behavior. So, there is an important question about the accuracy and sensitivity of these datasets which are acquired from different DEMs. This study deals with four types of DEMs, first is derivative from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER 30 m resolution), second is Shuttle Radar Topographic Mission (SRTM 90 m resolution), third is SRTM 30 m resolution and the fourth is the Advanced Land Observing STLT (ALOS 30 resolution). More than 35 morphometric parameters including drainage network, basin geometry, basin texture and basin relief characteristics were measured and calculated using these four types of DEMs and calibrated with topographic maps of 1:250 K and 1:50 K scale and also google earth maps. Results show that the SRTM 30 m is characterized by high accuracy and has a very good matching with google earth maps and topographic map of scale1:50,000. This research is dealing with the comparison of the morphometric parameters of the hydrographic basin based on the type of DEM. It is clear to conclude that the SRTM 30 resolution is the best type for hydrology and water resources study.