# Calculate area above elevation threshold?

I have a number of 95% isopleths (polygons) that represent animal home ranges. For each isopleth, I and want to calculate the Area (sq km) above 2000 meters.

My initial thought was to create contours from regional DEMs but because the lines do not close to form polygons, I am unsure how to calculate area.

An ArcGIS solution is preferred for this project.

First you need to reclassify the DEM data in 2 classes :

• Z < 2000 : 0
• Z > 2000 : 1

Then just convert the resulting integer raster to vector and keep class 1 only. That will make a 2000 meter area mask.

Finally, you just need to clip, union or intersect your animal range polygons and this new polygon mask to be able to calculate your area info in the attribute table.

• Can you indicate what tools you would use. Personally I'd use Con but Slice would also work. Spatial Analyst is required, B. Davis do you have access to this licence? If not you may need to use GDAL_Calc to make a binary raster... Commented Sep 14, 2015 at 22:21
• Indeed. As .B.Davis was asking for ArcGIS solution, i would recommend using Spatial Analyst but you could use another GIS like QGIS should you not have the SA extension. See here for detailed explanation : gis.stackexchange.com/questions/160278/… Commented Sep 15, 2015 at 6:46
• @Michael Miles-Stimson sorry for the delay. Yes, I do have Spatial Analyst. Your steps seem clear, but I am not sure how to "keep class 1 only" when converting the integer raster to a vector (I presume a polygon...). Additional info would be great. Commented Sep 17, 2015 at 11:59
• You can simply delete the 0 value polygons afterwards ;) Commented Sep 17, 2015 at 13:55
• That works, or supply no false value in the Con and there will be no other polygons.. example Con("Elev_Rast" > 2000, 1) will produce a raster with 1 where the Elev_Rast is greater than 2000 and NoData everywhere else; NoData values do not create a polygon with Raster to Polygon. Commented Sep 17, 2015 at 21:30