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I am trying to compute branching angles of drainage networks for roughly the western half of the U.S. Because many of these streams are non-perennial (don't have water all year), some of the standard data products won't work (Openstreetmaps, National Hydrology Dataset, Global Surface Water rasters). It seems the best approach is to use a flow accumulation raster.

I am aware of the Hydrosheds 15- and 30-arc second global flow accumulation grids, but they are too coarse. The higher the resolution, the better, but it looks like 10m DEM from the National Elevation Dataset is the best I can do. I am wondering if I can skip the steps of procuring and processing the data as I only need the flow accumulation. Deriving flow accumulation grids from DEMs seems like such a common task that I thought there would be more continental-scale flow accumulation grids available, but I can only find the Hydrosheds. Does anyone know of larger-scale products?

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The NHD distributes all of the elevation processing products along with the stream lines and catchments (Example for PNW). Note that these products are the "hydro corrected" products that are used to build the catchments, so they should essentially match flow boundaries and flow lines that are present in the NHD+v2 catchments. It is at the native 30m resolution of NED.

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The NHD HiRes is available for much of the country, but not all of it. This is at a 10m resolution (1/3 arc second). (NHD HR info page)

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  • Thanks, I didn't see these when I was poking around their site. I saw the coverage of the 10m DEM and I'm not sure it covers my entire region of interest. At the very least, this is 1/3 the resolution of Hydrosheds! – Jon Jun 13 '18 at 15:47

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