topic Re: Arc Hydro catchments question in Water Resources Questions

Arc Hydro catchments question

DanielSchatt — Tue, 07 Apr 2015 14:01:22 GMT

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

Re: Arc Hydro catchments question

SepheFox — Wed, 08 Apr 2015 01:13:57 GMT

Did you fill your DEM raster before generating the flow accumulation/direction rasters, Dan?

Re: Arc Hydro catchments question

DanielSchatt — Wed, 08 Apr 2015 14:12:56 GMT

Thanks Sephe, yes I did fill it.

Re: Arc Hydro catchments question

SepheFox — Wed, 08 Apr 2015 14:15:37 GMT

I see you had another question about the Basin tool. Did you try that? Did it work better?

Re: Arc Hydro catchments question

DanielSchatt — Wed, 08 Apr 2015 14:23:40 GMT

Unfortunately no, it crashes after a couple of hours when I run the Basins tool. Not sure why, I put in a call to Tech Support about it. Here are the error messages...any ideas?

Re: Arc Hydro catchments question

SepheFox — Wed, 08 Apr 2015 14:34:07 GMT

Ugh, that sucks. It looks like your machine is running out of memory. Is it a very large geographic area? Sometimes it helps to split it up into smaller areas. Here are some other tips:

ArcGIS Desktop

Re: Arc Hydro catchments question

SepheFox — Wed, 08 Apr 2015 14:37:54 GMT

Here are some other tips I came across. Some of these are useful even if your not using ArcHydro.

ArcHydro Problem Solvers

Re: Arc Hydro catchments question

DanielSchatt — Wed, 08 Apr 2015 14:43:36 GMT

Thanks Sephe, that’s what I thought at first but I don’t think memory should be an issue. I have 32 GB RAM and it’s just an average-size county. It is fairly flat so all I can think is maybe it’s trying to assign lots of cells to lots of really really small basins. I’ll post if I find out anything from the tech support.