Polygon filling out based on a polygon area inside/top of the polygon.

[ArtemLiebenthal]

I have a polygon layer of counties and another polygon shapefile of forest. I want now to fill out the county shape polygon fully in green where more than 30 % of the polygon is overlayed with the forest polygon. What are the steps to take?

[Katie_Clark]

My first thoughts on this...

1. Intersect the parcels with the forest polygons
2. Dissolve the forest polygon layer based on the parcel FID if there ends up being multiple forest polygons in a single parcel
3. Calculate the geometry in a new field for both the original parcel layer, and the dissolved intersected forest polygon layer.
4. Add a new field to the parcel layer for % Forest Coverage
5. Do a spatial join between the two layers
6. Calculate the percent coverage ((Forest_acres/Parcels_acres)*100).

Proceed to create your attribute driven symbology based on this field, where features with a % cover over 30 get a green fill.

Does that make sense? Perhaps there's an easier or more efficient way to do it, but that was the first workflow I thought of after brainstorming on it.