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Easy way to calculate area between polyline and polygon?

August 26 2009 | 0 comments
Categories: ArcGIS Methods, Map Data

I'm struggling to find a simple solution to calculate the area between a polyline and buffered polygon without having to trace the polyline feature.

Basically I have a 5 mile buffer around the US, and I want to calculate the area between the 5 mile buffer and -30m bathymetry (sea depth). I have my countour and buffer ready, but can't find a simple way to calculate the area between. I tried the Union tool, but it didn't work.

See the attached image to get an idea of what I mean.

Any suggestions?

Mapping Center Answer:

First, that's a much more complex problem than it sounds, just for the fact of how islands may or may not be involved. 

  1. What I would first do is create a polygon that represented land and the area within your five-mile buffer.  That may be as simple as running the buffer again on your land polygon and not using the Ring option. 
  2. Next use the Feature to Line tool and with your buffer as the input. 
  3. Use the Append tool to append these lines to your -30 bathymetric contour.  You will need to manually add four lines that demarcate the northern and southern extents for your study area on each coast.  These lines must fully intersect your buffer and the -30 contour; these lines are defining the limits of your polygon, i.e., how far down the coast of Mexico do you need?
  4. Create a new point feature class.  You will need to manually add least two points (one off the east coast, and one off the west coast) that fall between your buffer and the -30 bathymetric contour.
  5. Use the Feature to Polygon tool with the result of step #3 as the input, and use the point features from step #4 as the Label Features parameter (last one in the tool).  This will produce a set of polygon features--I think just the two you want.  As long as you're working in a geodatabase, you'll get the Area field automatically.


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