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Calculating Upstream Distance Between Point...   Lexie Haselton Nov 23, 2009
Re: Calculating Upstream Distance Between P...   Jeff Wickstrom Nov 25, 2009
Re: Calculating Upstream Distance Between P...   Lexie Haselton Nov 30, 2009
Re: Calculating Upstream Distance Between P...   Jeff Wickstrom Nov 30, 2009
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Subject Calculating Upstream Distance Between Point Datasets 
Author Lexie Haselton 
Date Nov 23, 2009 
Message Hi,

I have 80 monitoring sites snapped to a stream network for which I am trying to calculate the upstream distance to the closest feature in a separate dam shapefile (also snapped to that stream network).

I can calculate the closest distance along a network using Network Analyst, however I can't seem to specify flow direction. I can check my connectivity, and determined flow direction using Utility Network Analyst, but can't seem to calculate the upstream distance based on two shapefiles (you have to select individual points one at a time...).

Does anyone know about the functionality of either of these two tools and how I might make one of them work to take into account both flow direction, and distance between two point data sets? Am I missing something?

I'm out of ideas... 
   
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Subject Re: Calculating Upstream Distance Between Point Datasets 
Author Jeff Wickstrom 
Date Nov 25, 2009 
Message Hello Lexie,

Sounds like a Geometric Network model is what you are looking for. It has the concept of flow direction, etc. Here is some doc on it ... http://webhelp.esri.com/arcgisdesktop/9.3/index.cfm?topicname=what_is_a_geometric_network?

Note that you don't need a Network Analyst license to use it as it is part of core ArcGIS.

Jeff 
   
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Subject Re: Calculating Upstream Distance Between Point Datasets 
Author Lexie Haselton 
Date Nov 30, 2009 
Message Hi Jeff,

Thanks for your response. I was using a geometric network with Utility Network Analyst, and it does give me flow direction, but using Utility Network Analyst does not seem to provide an easy we to calculate upstream distance along a network for multiple points at on time. For example, I have 80 monitoring sites and want to calculate the upstream distance to the closest dam. With Utility Network Analyst you have to select individual monitoring sites and dam sites as opposed to one shapefile containing all monitoring sites, and one shapefile containing all dams.

How would I use a geometric network outside of Utility Network Analyst to calculate these distances?

Thanks!

Lexie 
   
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Subject Re: Calculating Upstream Distance Between Point Datasets 
Author Jeff Wickstrom 
Date Nov 30, 2009 
Message Hi Lexie,

That makes sense. So you want to use some of the functionality in the Network Analyst solvers (i.e. Closest Facility).

With a Geometric Network, you would probably need to write some VBA code to get similar results easily.

How about using a Network Analyst Network Dataset and a "one way" restriction on the stream lines? Network Analyst just won't help you automatically generate that "one way" or flow direction attribute field.

Jeff