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Intersecting layers to produce discrete polygons

03-05-2019 08:24 AM
New Contributor

I have several layers of vector data and I am trying to find areas which satisfy a set of criteria. These sites must be

- below a certain altitude

- within forest

- within 500 m of a river

- and also a minimum of 1 square kilometre in area.

I used the Intersect tool with my altitude, forest, and river data to find sites which meet the first three criteria. This is producing polygons which appear discrete but when selected turn out to be interlinked (based on being part of single polygons in the original data). This means I cannot then run Select by Attributes to find polygons larger than 1 square km.

Is there a process I can use that will produce discrete polygons?

Hopefully this screen grab helps to explain what I mean. With what appears to be one polygon selected in the attribute table of the intersect layer, all of the polygons within one polygon of the original forest data (green in the image) are selected so I cannot find the areas of the individual land parcels that meet my criteria.

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3 Replies
Esteemed Contributor

It looks like you have multi-part polygons.  Try exploding the multi-part polygons and then run Select by Attributes.

Occasional Contributor III

Just like Michael Volz‌ says - you'll need to explode your multi-parts.

MVP Emeritus