Application of an Automated Technique for Topographic Watershed Deriving Using DEM Analysis

Abstract

Basic topographic features play major role in deriving basin hydrological characteristics for water resources modeling. Algorithm used in this paper for defining watershed contours relies on digital elevation model (DEM) as primary input data. Accuracy of automatic deriving of watershed contours primarily depends on DEM resolution. On the other hand, accuracy can depend on raster method that is used for stream network delineation into Stream Network raster. To perform this function it is necessary to know how much water flows through each pixel. This means that it is necessary to set the threshold of how many cells flow into each downslope cell to recognize it as a stream. There are several ways to set up the threshold value and herein the calibration method is used. This paper treatsGornja Lisina source, where this method was used to determine watershed contours for 9 springs. Source DEM had 25 m resolution. Various threshold values were tested. For each value catchment area was calculated and compared to area values calculated using common hydrological methods.