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I have a set of settlement points near a coastline polyline, but not actually on the coastline. I need to eventually divide up the coastline polyline into "settled" coastline vs. "unsettled" coastline.

I believe the easiest way to achieve this is to cluster settlements together, and then use the coastline polyline as my edge, similar to what is done by the Delineate Built-Up Areas tool in ArcGIS:

ArcGIS delineate built-up areas

Afterwards, I'll be able to split up my coastline based upon whether or not a "built up area" touches it.

Can this be done using QGIS?

Edit: I cannot simply buffer my points and then intersect by my coastline, because the buffering does not actually stop at the boundary edge. For example, let's say I have some settlements on the mainland, then buffer it by 10k or whatnot in order to group them together and hit the coastline. This buffer not only hits the coastline, but it crosses over to the coastline of a deserted island. If I were to then intersect my buffered shapefile by my land shapefile, the result would be a patch of habitation on a deserted island!

settlement mainland to island buffer

  • If you wish to know whether this can be done in PostGIS you can always ask that as a separate question. – PolyGeo Oct 19 '17 at 4:26
  • Simplistic approach would be to buffer the buildings individually to a distance. Then clip to coastline. Crude, but you could then edit and delete the island. Another approach would be to use binning hexs from MMQGIS – Andrew Tice Oct 24 '17 at 19:21
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There is not any stand-alone tool like that, but you can do the job combining the basic tools.

  1. Buffer of the settlements (with dissolve option checked).
  2. Clip to remove those areas you are not interested in (ocean, rivers, etc).
  3. Select by location: Select those polygons with settlement inside.
  4. Save as... the layer with "Save just selected spatial objects" checked.

You can combine all these tools into a model to use it as many times as you need.

  • This is actually what I wound up doing, but never added my own answer! :) Not perfect but good enough for now. – srha Nov 21 '17 at 19:35

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