Watershed in ArcGIS
You can use the Watershed Delineation Tools (arcscripts.esri.com) to quickly delineate watersheds in ArcGIS.
- Download the the tool (here) and unzip.
- Start ArcGIS and open ArcToolbox.
- Load the Water Deleneation Tools
- right-click on "ArcToolbox" (the very top entry in the toolbox)
- select "Add Toolbox"
- navigate to the location where you unzipped the file, select it, hit Open
- You'll see the Watershed Delineation Tools (probably near the bottom of ArcToolbox)
- Open the Watershed Delineation tool
- browse to your DEM
- enter a tolerance value (large value = large watershed)
- outputs for the watershed, stream fetures, flow direction, and flow accumulation are automatically entered
- CAUTION: you'll need to change the output names if you decide to rerun the tool
- hit OK and wait for the watersheds to be generated