I need to summarize downstream information associated with each arc in an NHD dataset. I have a table with the downstream ID for stream segment but am not sure how to get all of the downstream IDs. Any ideas?

  • Are you using NHDPlus? If you can deal with 1:100k data (instead of the high-res 1:24k NHD), the Value Added Attribute tables of NHDPlus allow for extremely rapid downstream navigation.
    – dmahr
    May 14, 2013 at 22:37
  • Have you seen RivEX (www.rivex.co.uk) it can generate an adjacency table which you use to traverse upstream or downstream?
    – Hornbydd
    May 15, 2013 at 10:28


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