Flow Accumulation following roads and routing incorrectly

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01-14-2021 01:47 PM
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EmilyLoucks
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I am hoping to get some guidance with correcting some routing problems with flow accumulation grid. I am using ~1 m DTMs from the Washington Lidar portal to create a flow accumulation grid for some pretty small streams (drainage area <10 km^2) in NW Washington. I follow the typical steps of filling the DEM, generating the flow direction, then the flow accumulation. For some reason with this lidar, the flow accumulation is not routing correctly, following roads and not taking a reasonable direction based on observations of the lidar. In some areas it doesn't even look like there's a channel on the lidar but a stream was drawn. I attached some photos with examples of the problems I'm seeing.

I have done some digging on google and came across people 'burning' through culverts using ArcHydro tools, but are these only available in ArcMap? Is there a better workflow in ArcPro for fixing these routing problems? Is it a problem with using too high of a resolution for the lidar?

I am not really sure where I should start trying to fix these problems, so a few words of wisdom would be much appreciated! 

 

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