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Arc Hydro catchments question

Question asked by dschatt on Apr 7, 2015
Latest reply on Apr 8, 2015 by dschatt

hi all, I'm trying to delineate catchments from an elevation raster clipped to a county.  I'm using the Arc Hydro module to do so.  Specifically, I'm generating flow direction and flow accumulation rasters, then using the basic procedure of defining streams from the flow accumulation raster (Terrain Preprocessing --> Stream Definition), then a stream link raster from that  (Terrain Preprocessing --> Stream Segmentation), and then the catchments (Terrain Preprocessing --> Catchment Grid Delineation).  But the catchments that are generated don't cover all the area in the county (which was in the original flow accumulation raster).  For purposes of my analysis I really would like the entire area to be in one of the catchments.

 

So is this to be expected?  I would think all of the original flow accumulation cells would be assigned to a catchment.  Thanks for any help...

 

Dan

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