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I've a query, I'm trying to locate all the roads which are basically at risk of erosion (landslide?) when it's raining heavily for a municipality.

What I have to work with is this:

  • A shape layer containing lines for the roads (centerlines)
  • Contourlines for the terrain
  • Raster with elevation model
  • ArcGIS Advanced Desktop with 3d and spatial analyst

My first thought was to create some lines perpendicular to the roadlines, in a range of for instance 20 meters, and there after count how many contourlines i cross. This is pretty lowtech, but so far it's the best I've come up with.

Does anybody have a smarter approach? Or perhaps tried doing something similar?

Two kinds of terrain types that should be highlighted/selected

Example of approach

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    You would not find risk areas when the road is parallell to the slope with perpendicular lines. Try creating a slope raster from the DEM, split roads into segments of 100 m (or whatever you want), buffer segments, then run zonal statistics with the segments as zones and slope raster as value raster. Then you will have a mean slope for each 100 m segment. – BERA Jul 16 '18 at 9:26
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    @BERA is right. You could do even an easier way if you know your slope range prone to landslide. For the sake of example lets choose all the slopes above 20 degrees. Create slope raster, reclassify to your needs, convert raster to polygon, buffer your roads depending on road size, then intersect/spatial join/zonal statistic, whatever tool that does this kind of things. Some tweaks in the attribute table and you are done. – alecsx Jul 16 '18 at 19:21
  • The add surface information tool in the ArcGIS 3D Analyst toolbox will populate a line with the value of a surface (in this case slope). You will need an advanced license to use this tool. – GBG Jul 16 '18 at 20:57
  • Thank you for all the replies, I will give your suggestions a try next week as other things became more pressing. – FoolzRailer Jul 19 '18 at 7:04

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