# How to calculate percent of polygons covered by a buffer

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04-27-2017 01:26 PM
New Contributor III

Hi all,

I have thousands of points across Canada, as well as thousands of polygons. Each polygon represents a population (approximately 550 people). The points are across a rail network. What I need to do is find out the population within a half mile radius of each of these points.

For each Polygon I know the population density, and I've created a 0.5 mile buffer around each of the points, but I can't calculate the number of people in each 0.5 mile radius because many of the buffers contain many polygons, each with a different population density and with different amount of coverage of each polygon.

Any help would be very appreciated!

Please see attached file for reference

-Zach

1 Solution

Accepted Solutions
Esri Esteemed Contributor

A question first: I noticed in the attached image that the two buffer polygons just left from the selected buffer overlap. Will you be handling the overlap in some way?

What I would do (ignoring the overlap between the buffer polygons to keep it simple), is first add a field with the population density to the polygon featureclass. Next, I would intersect the buffers with the polygons. The resulting intersect area and "joined" population density can be used to calculate the population for each intersecting area. Based on a unique id of the buffer polygons you can dissolve the featureclass to create the buffer polygons and sum the population within each buffer polygon (use the statistics option in the dissolve tool).

3 Replies
Esri Esteemed Contributor

A question first: I noticed in the attached image that the two buffer polygons just left from the selected buffer overlap. Will you be handling the overlap in some way?

What I would do (ignoring the overlap between the buffer polygons to keep it simple), is first add a field with the population density to the polygon featureclass. Next, I would intersect the buffers with the polygons. The resulting intersect area and "joined" population density can be used to calculate the population for each intersecting area. Based on a unique id of the buffer polygons you can dissolve the featureclass to create the buffer polygons and sum the population within each buffer polygon (use the statistics option in the dissolve tool).

New Contributor III

YES thank you!!!

The big thing I was missing was the dissolve step, I'm new to GIS software and didn't realize exactly how it worked!

Thanks again,

Zach

Esri Esteemed Contributor