Weighted flow accumulation?

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06-27-2012 06:08 AM
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FrancescaVerones
New Contributor
I have a problem with Flow Accumulation.

I have my DEM and my rivers and I followed the following steps:
1) Terrain Processing>DEM Manipulation>DEM Reconditioning.
2) Terrain Processing>DEM Manipulation>Fill Sinks
3) Terrain Processing>Flow Direction
4) Terrain Processing>Flow Accumulation

Now I have a layer which is a 0.5° raster with water uses from surface waters. In each pixel the amount withdrawn in that respective pixel is given. I now want to accumulate these withdrawals, because once I have withdrawn a certain amount in one cell, this amount is ging to miss in the downstream river as well. Therefore I would like to put this into ArcHydro as some kind of weigth. This is possible in the Spatial Analyst, but the values I get there seem strange to me.

Does anyone know how I can do that?
Thanks a lot!
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MarkBoucher
Occasional Contributor III
Sounds like a job for geometric networks. Arch Hydro will build a geometric network based on hydrologic layers it generates.

I did an ArcGIS desktop search for "accumulation" and found "Finding the upstream accumulation" and it sounds like it would do what you want. I'm not sure if it will create a new raster with the results, but it might at discrete points/junctions in the geometric network. If it will save the results, maybe you could make your catchments small enough to make it discrete enough for you.
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AnandJayakaran
New Contributor
Have you ever experienced the case where: in the Terrain Preprocessing menu, the 'Weighted Flow Accumulation' tool is simply not present? The list stops at Slope; it does seemingly not include Slope Greater than 30, Slope Greater than 30 and Facing North, nor Weighted Flow Accm. Any ideas on this? I've prepared a DEM allll the way through these prep tools and am ready to accumulate!

All the help I can find seems to claim that that's exactly where they should be. I do not have the Dot Net software installed, I don't believe. Could that make a difference?
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MarkBoucher
Occasional Contributor III
I'm using Arc Hydro for ArcGIS 10 (version 2.0, September 15 2011). I've never used "Weighted Flow Accumulation" and so haven't notice if it was there or if it was missing. My typical work flow doesn't take me that far down the Terrain Process menu.
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