DEM-based GIS algorithms for automatic creation of hydrological models data

Abstract

In this paper the authors discuss the Digital Elevation Model (DEM) based GIS algorithms, applicable for automatic creation of input data needed by hydrological models. The expected source of DEM data are standard digital data sets that a modeler can purchase from the official data sources. The DEM has to be cleared from errors and prepared for standard hydrology usage as the depression less version, or a version of DEM where only small depressions are filled-in, while larger depressions are extracted as separate objects. The slopes and aspects are calculated from such DEM. The flow accumulation image is created using slopes and aspects and using information about large ponds. From flow accumulation image the surface drainage network is extracted with user-specified density. Based on slopes and aspects, the catchment is delineated into subcatchments, the areas drained by each river segment. Finally, the model-specific parameters like length of flow segment along the terrain and along the river to the subcatchment outlet, slope of those segments, subcatchment shape factor, or subcatchments mean or weighted slope are calculated. Paper explains the used algorithms and emphasizes the problems one can encounter during the usage of DEM data using examples from River Drina catchment. Finally, the authors comment on overall usability of presented GIS algorithms, especially if purchased data are of low quality. .