Using Ifsar and Srtm Elevation Data for Watershed Delineation of a Coastal Watershed

In this research, Interferometric Synthetic Aperture Radar (IFSAR) and Shuttle Radar Topography Mission (SRTM) data are used to delineate a portion of the Saint Louis Bay watershed (Mississippi). In addition to these two digital elevation databases, the National Elevation Data (NED) and the United States Geological Service’ Digital Elevation Model (USGS-DEM) are also used for delineation. Results show that, SRTM elevation data produce optimum delineation results comparable to delineation achieved using NED when areas and sub-basin perimeters are compared. Vertical topographical parameter values, however, differ substantially in flatter terrain. SRTM delineation provides overland plane slope values up to 35 times higher than those provided by the NED delineation. Flatter sub-basin’s river slopes show up to 500 percent difference when comparing slopes provided by SRTM and NED. These results could be significant for hydrological simulation. Processing time and difficulty on getting final delineation results incur in limitations on the direct use of IFSAR data. Future improvements on BASINS may allow an efficient use of IFSAR data for watershed delineation. Conclusions are drawn from the comparison on the quality of the delineations and it’s usefulness in hydrological modeling.