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I am using TauDEM in ArcMap 10.3.1 to try and calculate flow accumulation and generate stream networks for HUC10 watersheds. I am using 3m DEMs acquired from the National Map.

The HUC10 I am working with consists primarily of a segment of a large river, and there are several large tributaries flowing into this river segment, but each tributary is part of a separate HUC10. You can see this in the following image, the HUC10 I am working with is highlighted in blue and the tributaries are coming in from the top of the picture:

enter image description here

I am trying to calculate flow accumulation only for the highligted HUC10, so I have clipped it from the rest of the DEM for my analysis. My specific problem occurs when calculating the flow accumulation (based on D8 flow direction) - the flow accumulation will start at the furthest upstream portion of the main river (left hand side of the above picture), and the raster cells will increase in value until they reach one of these incoming tributaries. At this point they intersect the edge of my clipped DEM as if it were an outlet point instead of continuing down the main river.

I have tried buffering the DEM various distances outward from the watershed boundary to try and avoid this problem where the flow accumulation intersects the edge and this works sometimes but other times it just allows the flow accumulation to flow further up the incoming tributaries. See photo below, the flow accumulation grid (based off of a DEM with a 500m buffer around the watershed boundary) is displayed at 50% transparency on top of an aerial photo for reference:

enter image description here

Does anybody have any ideas on how I can make the flow accumulation continue down the main river instead of up the incoming tributaries?

I'm sorry if my explanation of the problem was not adequate, I have never used the GIS stack exchange before. Please let me know if you need any further information or clarification.

  • You have to force flow into main channel, search this site for stream burn – FelixIP Sep 11 '15 at 7:46
  • This would require me to use an existing stream network to burn values into my DEM, correct? I'm not sure if this would work because I am trying to generate a stream network from this DEM, not recreate an existing network. Is there a way to alter the DEM only in this specific area to prevent the flow from traveling up the tributary? – David Sep 11 '15 at 14:24
  • Draw 1 Srteam=main channel – FelixIP Sep 11 '15 at 20:26
  • Building walls around your clipped DEM may be another option, but I would opt for burning in the main stream channel as FelixIP has suggested. – jbosq Sep 15 '15 at 20:49

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