Digital Elevation Model Based Hydro‐processing

The article describes a newly implemented routine, called DEM hydro‐processing, which was added to the overall capabilities of the ILWIS-GIS package developed at ITC. A few novel approaches have been incorporated within the package allowing the user to derive a realistic river and basin schematization, e.g. being able to deal with closed basins or lakes in combination with a user defined construction of topology and extraction of a river network using variable drainage thresholds. A large number of attributes are computed assisting efficient hydrological model input preparation or terrain evaluation in a more general sense. Information obtained through other generic (GIS or Remote Sensing based) functions available within ILWIS, e.g. classified land cover map or screen digitized sections of the river network in flat areas, can be easily incorporated and used to effectively schematize and parameterize a model area under consideration. As example a SRTM‐based DEM is selected as this dataset has a near global coverage at a resolution suitable for hydrological analysis of larger river basins.