Limitation of automatic watershed delineation tools in coastal region

In this research article, the Sabarmati river basin, India, which joins the Gulf of Khambhat, has been chosen to demonstrate the limitation of various automatic watershed delineation tools. The basin area of the river has been delineated using CARTOSAT 1 (20 m), ASTER V2 (30 m) and SRTM (90 m) Digital Elevation Models (DEMs) with ArcGIS Hydrology, ArcHydro and ArcSWAT automatic watershed delineation tools. Delineation of Sabarmati river using ASTER V2 (30) DEM by ArcSWAT automatic watershed delineation tool produced the best results with an error of only 0.75%, as compared to the area reported in India WRIS. The SRTM DEM performed consistently better than other two DEMs in case of all three automatic watershed delineation tools and produced only 2.99% average error. ArcSWAT automatic watershed delineator is the most accurate watershed delineation tool in comparison to other two tools and produced a lowest average error of 1.57%. ArcGIS Hydrology tool, using all the DEMs, produced an average error of 11.55%, which is the highest amongst all of the three tools. In general, the automatic delineated stream network fails to join the main river and some area of the watershed is always left out.