[GRASS-user] Problem with r.watershed in Spearfish

[Margherita Di Leo]

Hi Milton,

Thank you for answering.

Milton Cezar Ribeiro wrote:
> Margherita,
>  
> Check with g.region -p and see how many 100x100 pixels you have.
GRASS 6.5.svn (spearfish60):~ > g.region -p
projection: 1 (UTM)
zone:       13
datum:      nad27
ellipsoid:  clark66
north:      4928000
south:      4914000
west:       590000
east:       609000
nsres:      100
ewres:      100
rows:       140
cols:       190
cells:      26600

> May be it is very small for your threshold.
I don't think so, because the streams are well delineated. The problem 
is the value assigned to them (zero).

Cheers
>  
> best
>  
> milton
> 2010/1/25 Margherita Di Leo <diregola at gmail.com 
> <mailto:diregola at gmail.com>>
>
>     Hi list!
>
>     I often used r.watershed without problems, but today i had a very
>     strange one. Please can anyone verify that?
>     I used Spearfish mapset, map: elevation.10m:
>
>     g.region res=100
>     r.watershed elevation=elevation.10m at PERMANENT threshold=100
>     accumulation=acc_10 drainage=dir_10 stream=str_10 convergence=5
>     memory=300
>
>     The stream map has many streams with 0 value.
>     The problem is only with res=100.
>     Does r.watershed fail?
>
>     Thank you
>
Eng. Margherita Di Leo
Ph.D. Candidate
Methods and Technologies for Environmental Monitoring
Department of Environmental Engineering and Physics (DIFA)

University of Basilicata 
Campus Macchia Romana
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Italy

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