I have point elevation data and road layers for a region.

How do I show the road sections that are below 10 ft elevations?

I am using ArcGIS Desktop 10.3.1.


Convert your point data to raster data, then to contour lines. Extract both the 10' and the lowest elevation (possibly 0') lines, convert them to polygons and clip your roads using that polygon.

Or, as @Spacedman pointed out, use Kriging and polygonize instead of contour lines.

  • 2
    Better to convert point to raster (kriging, or IDW), then threshold on <=10 ft, then polygonise, then clip. Not convinced a contour line algorithm will give you polygons if the line ends at the boundary... – Spacedman Oct 22 '18 at 14:53
  • I converted the points to raster through idw but how to set the threshold on <=10 ft? The IDW shows the minimum value of -4.77 and max of 348.35. – BPS Oct 22 '18 at 15:44
  • @Spacedman: Will you provide me some details for your method, please? – BPS Oct 22 '18 at 16:43
  • @BPS in QGIS, use the Raster Calculator to create a raster that is 1 where the DEM is < 10 and 0 elsewhere. Then I run the "polygonize" algorithm and that creates polygons. I can then intersect these with the lines. Equivalent ArcGIT operations must be there somewhere... – Spacedman Oct 22 '18 at 17:18
  • 1
    If you are confident in ArcGIS then you can probably find its raster calculator and create a raster thresholded at 10-feet. The you can find its raster-polygon conversion and get polygons that are above and below 10 feet. Then you can use its polygon-line overlay function and get the roads below 10 feet. – Spacedman Oct 22 '18 at 19:53

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