SOARS(2): WATERSHED DELINEATION - A COMPARISON OF AUTOMATED EXTRACTION METHODS

The creation of a digital elevation model (DEM) and the delineation of the entire Cuyahoga River watershed and sub-watersheds were key components of the 2003 NASA Scientific Outreach and Applications using Remote Sensing (SOARS) project. The delineation of entire watershed and sub-watersheds was performed using different data inputs and software applications. Three source DEMs were inspected as potential inputs: a mosaic of the 7.5 minute USGS DEMs, the seamless National Elevation Dataset, and a DEM created from the 1:24,000 DLGs. The software applications used for delineation were Rivertools and ArcView (using the Hydro extension). There were notable differences in the boundaries derived using each software application on the various data sets. The discrepancies in the datasets responsible for the differences were investigated. The subsequent results were rigorously inspected in the field with wireless handheld GPS units and traditional survey techniques to select the boundaries which best represented the actual drainage of the Cuyahoga River watershed for purposes of the project. The results were compared with the watershed boundaries from ODNR. A pivotal portion of long-term hydrological process modeling is to validate source elevation products and their relationship to watershed boundaries.