I am looking to group polygons together that are upstream of a trunk sewer line (Main Pipeline). Basically, the trunk sewers all have other (regular) sewers branching off of them. All of these sewers are currently contained in the same feature class (Sanitary_Pipes). The polygons that I want to group are in their own feature class (Sanitary_Catchments) and overlap with Sanitary_Pipes. The goal is to group together the polygons that overlap with the string any given string of connected regular pipes that branch off of a trunk pipe.

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In the screenshot above, the thick green lines are trunk sewers, red lines are regular sewers, the points are manholes along the sewers and the green polygons are catchment areas that are a part of Sanitary_Catchments. The highlighted area is an example what I'm trying to do; all of the polygons that overlap with the set of connected pipes that are upstream of the trunk become grouped.

Is there any sort of tool/collection of tools that can do this?

  • Are all pipe intersections at end vertices of all intersecting features, or can you have a pipe feature intersect another pipe feature at a point that's not its end point? – Emil Brundage Jul 23 '19 at 15:45
  • Your first assumption is correct, all pipe intersections occur at end vertices. – Reed Jul 23 '19 at 15:49
  • By group, what do you mean? Create a single polygon for each branch sewer group? Attribute each catchment polygon with an attribute from the branch sewer? – Emil Brundage Jul 23 '19 at 15:55
  • It'd be the first thing you mentioned, I'm trying to create a polygon for each branch sewer group with all of these newly created polygons being in the same feature class. – Reed Jul 23 '19 at 18:08

This is the workflow I'd recommend:

  1. Add a definition query to your pipes for your branch pipe (Trunk = 'No')
  2. Buffer pipes with a small distance (1 foot), dissolve type ALL
  3. Split your buffers using Multipart to Singlepart
  4. Add a unique ID value to each singlepart buffer
  5. Spatially Join buffer unique ID to your pipe features
  6. Spatially join pipe unique ID to your polygons
  7. Dissolve spatially joined polygons by unique ID
  • 1
    Dissolve won't work for any group of pipes having node with degree > 2. Small buffer, dissolve all, explode to single part will work better. – FelixIP Jul 23 '19 at 20:58
  • @FelixIP I'd forgotten this fact. I've updated my answer. – Emil Brundage Jul 23 '19 at 21:27

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