I have a challenge which I am trying to solve. I have a linear stream network and a polygonal zone dataset - and I am trying to summarise the length of the network that is upstream of a particular zone - expressed as polygons.
If you look at the attached jpg, I would like to work out how much of the stream network is within zone a, and has no further zone b/c upstream.
It's a bit beyond a simple intersect as the stream sections can go from zone A to C and from C to A - so the key is identifying the last change, and working upstream from that - or starting from the top and working back down.
I had considered writing some script to walk down each stream section accumulating stats until leaving Zone A - but data quality issues prevented that - issues I think I can resolve with network analyst. But there is no point asking for a license to sort out the dq issues if I can't do the main task!
So - my question - is it possible within in Network Analyst?
Can you think of any way to do it manually, without network analyst?
broadly speaking - what sort of workflow could help flag these sections of network?