Geographic Information Systems Stack Exchange is a question and answer site for cartographers, geographers and GIS professionals. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Imagine that I have the need to determine landlocked countries. Is there a way to do it automatically? Any known implementations?

The target platform on this will be ArcGIS.

share|improve this question
Using topology, it looks trivial: Landlocked countries are the ones that do not touch sea regions, right? – julien Nov 29 '10 at 17:52
right, but I do not have "sea regions" defined. I actually need to find out landlocked parcels (yes, they can happen - at least in Manaus - Brazil). I need a solution that does not involve topology, because I don't have enough operators with sufficient knowledge to operate it. I need a "press a button" solution. – George Nov 29 '10 at 19:04
Does it need to be on a global scale? AFAIK Esri's topology is planar. If at a more local scale, I suppose it might simplify things to draw an "outside polygon" (to borrow a coverage concept) and designate a sea polygon. You'd also need lines separating where the rivers end and the sea begins - otherwise Bolivia would not be landlocked by virtue of its rivers. – Kirk Kuykendall Nov 29 '10 at 19:35
I guess it might work. I did not want a ModelBuilder approach, but it's ok. Thanks for all the help – George Nov 29 '10 at 20:35
up vote 6 down vote accepted

Topology will do this - polygons to line - build topology find "left = 0" (outer line which is sea without creating sea polygon) then inverse the selected features use this selection to find your original polygon. Should be all internal polygons 'landlocked'

Have done this in reverse to build a sea polygon mask - can be automated with modelbuilder.

share|improve this answer

You could use the 'Select by Location' function in ArcMap and choose a criteria that best fits (such as 'within X m' of a polygon). I don't think this is as sophisticated as using topologies but it has the benefit of being scriptable in Python and can be made into a button you click.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.