Geographic Information Systems Stack Exchange is a question and answer site for cartographers, geographers and GIS professionals. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I'm having difficulty merging datafiles from the NHD while still keeping functionality as a geometric network. I'm using ArcGIS 10.1, so the USGS merge tool isn't an option.

Using the medium resolution staged NHD files, I've tried 1) merging the NHDFlowline files and then building a geometric network - results in a network with "Indeterminate Flow" and 1 type 12 error; and 2) putting two NHDFlowline files into a new Feature dataset inside of a file geodatabase, then constructing the geometric network - results in a network with "Indeterminate flow" also.

Not sure if I am mis-specifying the geometric network attributes, missing a step or something else.

share|improve this question
up vote 3 down vote accepted

Yep, turns out I wasn't honoring the wisdom of the beginner's mind and I jumped right to an assumption that my problem was way more complex than simply not having run the Set Flow Direction tool. Entries in the attribute table of the NHDFlowline file suggest that "WITH_DIGITIZED_DIRECTION" is the right parameter to go with - and it seems to check out visually.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.