line direction in geometric networks?

02-28-2011 01:45 PM
New Contributor
I am currently investigating ways to model flow in our drainage network using ESRI tools. I have successfully set up a geometric network using our drainage pits and pipes, set sources and sinks as well as flow direction and modelled this using the ???Utility Network Analyst??? tool.

My specific question is: Does line direction within the network need to be set to correspond to flow direction, or is it sufficient to just set up your network with sources and sinks to indicate flow?

My reason for asking is that I have found a number of scripts through the ESRI user forum which can flip lines to match flow direction and I was curious to know if there was a specific reason why people may perform this task?

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New Contributor
Hi Alan,
Thanks for your reply.

I have played with it some more and found that just setting sinks then setting flow direction should by and large suffice for us.

That script may prove useful later on though.


Hi Robert,

For some people, the Set Flow Direction button on the Utility Network Analyst toolbar doesn't suffice, as their geometric network contains loops and/or they have conflicting sources/sinks.  In this case, they need to set flow direction using another tool.  The simplest tool is to set flow by digitized direction, in which case, they need to have the digitized direction aligned with the flow direction they desire.

If, however, setting flow direction using the button on the Utility Network Analyst toolbar works fine for setting the flow for your own geometric network, then you don't need to worry about the digitized direction of the lines.

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