I have a grid of lat/lon points all over the state of Texas and I'm trying to find the flood zone and base flood elevation for each of the points. I've found the flood zone fine by doing a spatial join, but the base flood elevation layer is line data (cross sections) and I don't know what to do - looking around it seems like I might have to generate a DEM or something? How do I interpolate and find out what the BFE is supposed to be? I just don't know what the process should be.

I have a list of lat/longs (point geometries) and I need to get the base flood elevation for them. FEMA provides cross sections for base flood elevations (i.e. not a raster DEM, but line geometries) and what I need is to convert the cross sections to something I can run an algorithm with the lat/longs as the input and the base flood elevation as an output (added to the attributes table for the points) - or maybe there is some method to run this as-is using the line geometries?


  • The BFE are the orange lines in your map? Do the lines have relevant attributes? – Spacedman May 18 '18 at 22:18
  • Yes those lines are cross sections of the BFEs and they do have attributes (i.e. elevation) – Ben May 19 '18 at 13:41
  • Everyone who put the question on hold - can you please read updates? – Ben May 21 '18 at 11:13
  • You say "...convert the cross sections to something I can run an algorithm with the lat/longs as the input..." So whats this algorithm? What software are you running it in, what are it's input requirements. It is unclear. Suggest you edit your question and add more detail, especially the image, whats all the purple stuff? – Hornbydd May 21 '18 at 22:24

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