Re: [GRASS-user] Question about r.watershed and flow accumulation grid

Micha Silver Fri, 13 Feb 2015 12:16:03 -0800

On 02/13/2015 08:48 PM, Thomas Adams wrote:

Stefan,

A fair question; since I know the stream topology from personal experience it is clear that there should be no break in the stream network and the flow accumulation grid should reflect that. I am seeing the flow accumulation values break at a point where they should continue to accumulate downstream.

Are these breaks possibly caused by null pixels in the DEM?

Tom

On Fri, Feb 13, 2015 at 11:43 AM, Stefan Lüdtke <[email protected]> wrote:

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Hi Tom,

just out of curiosity, what do you mean by "break in the flow
accumulation"?

Cheers,

Stefan

On 02/13/2015 07:12 PM, Thomas Adams wrote:
> Hello all!
>
> I'm making use of the flow accumulation grid in GRASS 6.4.5
> generated from r.watershed using the SFD (D8) flow algorithm. The
> DEM has a 250m spatial resolution. What I'm getting is a break in
> the flow accumulation in a few locations which is causing me
> serious problems with subsequent processing (with help from some
> here, I have put together some scripting to generate a pixel
> connectivity file for a distributed hydrologic model).
>
> Besides going to a higher resolution DEM, are there any thoughts as
> to how I can eliminate these flow accumulation breaks?
>
> Thank you, Tom
>
> --
>
>
>

> _______________________________________________ grass-user mailing
> list [email protected]
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- --
Stefan Lüdtke

Section 5.4- Hydrology
Tel.: +49 331 288 2821
Fax: +49 331 288 1570
Email: [email protected]

Helmholtz-Zentrum Potsdam
Deutsches GeoForschungsZentrum GFZ
(GFZ German Research Centre for Geoscience)
Stiftung des öff. Rechts Land Brandenburg
Telegrafenberg, 14473 Potsdam
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Re: [GRASS-user] Question about r.watershed and flow accumulation grid

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