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Watershed Delineation

August 15 2008 | 0 comments

Is there a resource to look at to follow a pre-described path for delineating a watershed. I was given an assignment that involves calculating the difference between two watersheds that I need to create around two specific points.
Any help would be great.

Mapping Center Answer:

If you have a DEM and if you have the Spatial Analyst extension, then creating a watershed is fairly straightforward. Watershed is one of the Hydrology Tools in the Spatial Analyst toolset of ArcToolbox. Using this tool you can defined as the total area flowing to a given outlet, or pour point. For your analysis, the point points are the two points you need to create watersheds from.

Note that you will get a better result if you first snap your pour points to a cell in your DEM that has higher flow accumulating in it. To do this, use the SnapPour tool before using the Watershed tool. Of course, the results are also a function of the resolution of your DEM.

Once you are done, you can simply multiply the number of cells within the watershed by the size of a cell in area to get the total area of the watershed.

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