In this tutorial, we are going to delineate a Watershed in ArcGIS using Hydrology tools.
A watershed is the upslope area that contributes flow to a common outlet as concentrated drainage. It can be part of a larger watershed and can also contain smaller watersheds, called subbasins.
To start delineating a watershed; We need to download a digital elevation model of our study area; we usually use The USGS Earth Explorer which is a quick and easy online tool to download free Landsat imagery & other remote sensing data.
After downloading and inserting DEM raster in ArcGIS, we are going to use The hydrologic modeling tools in the ArcGIS Spatial Analyst extension toolbox to automatically delineate the watershed.