Automated Watershed Evaluation of Flat Terrain

Catchment area and watershed delineation is a common task in hydrology. The determination of the catchment is still as a challenge considered being crucial key issues particular in flat terrains. Three concepts could be briefly identified through: the manual delineation of a catchment based on a topographic map with contour lines which is a difficult task for flat terrains, by combination of field survey or evaluation of satellite images. The present research is focus on evaluating the possibility to delineate catchments from flat and arid areas by means of DTM avoiding hard techniques like river burning or other manual hydrological DTM corrections. Three GIS packages were used (Arc Hydrotools, TNTmips and RiverTools) within two DEM: the 90 m and 30 m SRTM in addition to the ASTER 30 m, the application sample presented by western Iraq desert—Ubaiydh wadi. A brief review is given how the delineation algorithms have been developed since the 1980’s. Where result shows that automated watershed analysis of flat terrains is cannot be done without manual evaluation and correction either by using several seeding points or river burning technique.