How to find area of overlapping polygons?

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05-24-2013 10:53 AM
ShannonArmitage
New Contributor
I have three different polygons that overlap in different places and I want to find the total area of all the polygons.  I'm worried about getting a "double" or "triple" count of the area where the polygons overlap. 


Some info on the layers:

The largest layer is a boundary polygon of forest service land with one attribute, another layer is land classified by the Department of Land Management as harvestable (for timber) and part of this overlaps the first layer and the third layer, the third layer is land classified for timber management by a different department.

I would like to know the area of these three layers without double counting the overlapping part.

I am new to forums so I apologize if I use incorrect procedure
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3 Replies
ChristopherBlinn1
Regular Contributor
Tibbs,

Have you taken a look at the Union tool?

It should start you in the right direction.

Hope this helps!

Best,
Chris B.
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LukeWebb
Occasional Contributor III
Tibbs,

Have you taken a look at the Union tool?

It should start you in the right direction.

Hope this helps!

Best,
Chris B.


Yes you can union them and the output will be what you asked for.

PROVIDED ... you have no overlapping features in any of the individual layers.. this will cause double counting to happen.

If you just want the total extent.. you can dissolve the union output and be sure that no double counting has happened.
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ShannonArmitage
New Contributor
Thanks, I ended up using the Merge tool and used the output feature property rule "mean" for the acreage field in each layer. I'll try the Union and dissolve to double check my answer.

Thanks!
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