Combining tax parcels with slope polygon

[JakeBrenner]

I'm working on an Open-Space Inventory and I need to create a map of any tax parcels that contain slopes greater than 15%. I've created a polygon from the original slope raster file, but I can't seem to figure out the right operation/combination of properties.

I've included a screenshot of a similar operation which resulted in a tax parcel map highlighting parcels that are within a 100m stream buffer.

Thank you for your help.

[EricKrause]

This is a bit outside my area of expertise, but I'll give you my thoughts (you might have better luck on the Spatial Analyst forum).

You need to think about how you want to define slope for a polygon.  Do you just want to average the slopes within each polygon?  Or do you want to find the maximum slope within the polygon?  Or something else?

Almost certainly, you're going to want to use the "Zonal Statistics as Table" tool in the Spatial Analyst toolbox, but you need to think about how you want to define the slope of an entire polygon.  Once you make the table using MEAN or MAX (or another criteria you decide), join the table to the tax parcel polygons.  You can then select all tax parcels with a slope above 15%.

[JakeBrenner]

Ah, I apologize for not being clearer. I already have the slope polygon - I used a raster that just showed areas where slope was greater than 15% and just converted that to a polygon. All I care about is a binary distinction - under 15% or over 15%.

All I need to do is use the slope polygon to create a new tax parcel map that makes a similar binary distinction by individual parcel - "does this parcel contain areas with a slope greater than 15% or not?", producing an output that highlights parcels that do and leaving blank those that don't.

[EricKrause]

So you already have a polygon feature class with a field indicating the slope?

If that's the case, then right-click the layer in ArcMap, and open properties.  Under the Symbolization tab, click "Quantities" on the left, then "Graduated colors."  For the Value field, give it the field containing slopes, then select a Color Ramp that you like.  Then click Classify.  Change Classes to 1 and Method to Manual.  On the right, click on the Break Value, and type 15.  Click Ok.

This should symbolize all polygons below 15% slope as one color and all polygons above 15% as another color.

Does that answer your question?

[PavanYadav]

I understand that you have two feature classes: 1. Parcel, and 2. Slope. And, the task is getting the slope information from the slope feature class to the parcel feature class. I think you would like to add an attribute field in the parcel that will contain 1 and 0 values to determine if an individual parcel contain areas with a slope greater than 15% or not. In that case you, you may want to use the Spatial Join (analysis) tool. This tool joins attributes from one feature class to another based on a spatial relationship. The target features and the joined attributes from the join features are written to the output feature class. This how I would use this tool:
- In the slope FC, add a field called slope, and assign �??1�?? to the all features that have slope value >15%. Use the tool. This field will be carried over in the output parcel feature class.

I would also recommend that you review other overlay tools, located in the Analysis toolbox.

I would like to know what if only 5% of the parcel area covers >15% slope feature. Should it get 1 or 0?  Or, area is not important? e.g. if parcel touches or partial/full overlap the slope feature class get irrespective to how much area it covers. If area is important, try the Intersect (Analysis) tool. Please also review the Zonal Histogram tool, you might find this tool helpful.

[JakeBrenner]

Problem solved:
- select attributes
- select features from: parcel map
- input layer: slope polygon
- features intersect the Source layer feature