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I’m working on a project where I need to estimate about 1400 pipe inverts using the adjoining pipes and manholes. The problem is a lot of the adjoining pipes are missing elevation data as well, so there are long segments of pipes missing data. I was wondering if anyone knew of an automated way to estimate the invert elevations. I haven’t had to estimate the inverts for this many pipes before, and I realize doing so one by one would take a lot of time. I have extracted upstream and downstream rim elevations using the USGS DEM, and using minimum slope would work for this analysis as well. Please let me know if you have any suggestions.

I'm using ArcGIS Advanced with spatial and 3d analysis. My dataset isn't in a geometric network.

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Just off the cuff.. you might try first extracting the endpoints of your line features, then extract the DEM elevation values for line endpoints and the manholes.

1) Feature Vertices To Points (Data Management): Turn your pipe line features into endpoints. Note the graphic describing your different point_location options.

2) Extract Values to Points (Spatial Analyst Ext): Identify your DEM and get the elevation values for your two pointsets.

..as an aside, I'm assuming your pipe is buried, so I'm guessing you'll need a post-processing step (Field Calculator) to subtract the presumed/average depth of your pipes across that pointset.

....also, fair warning, but I think that USGS DEM is going to be pretty coarse for your use case. Is there a local government/authority you can contact that might have a higher-detail DEM more suitable for your purposes? I think the estimates you create from this exercise will result in very "loose" dependability.

  • Thanks for your help. I'm going to use that approach and compare it to the information that looks reliable to see if it makes sense. I appreciate it. – smw Feb 9 '15 at 16:48
  • First thing to check if pipes are digitised in the right direction. When this done, I'd suggest to do interpolation between known pairs (script required). Best approach - interpolate depth and subtract it from lid level (DEM). This guarantee all nodes under ground and not ridiculously deep. Conflicts still possible - positive pipe gradients. – FelixIP Feb 9 '15 at 19:16

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