[GRASS-user] v.water.outlet

[Moritz Lennert]

On 05/01/12 12:16, Paolo Cavallini wrote:
> Il 04/01/2012 20:55, Micha Silver ha scritto:
>
>> I guess you mean r.water.outlet?
>
> Yes, sorry.
>
>> 1- The input must be the drainage *direction* map from r.watershed.
>
> ok
>
>> 2- And it's crucial that the easting and northing parameters for the
>> outlet point lay
>> exactly on a stream. Zoom in very close to the streams raster at the
>> outlet point and
>> check for the exact coordinates.
>
> Checked, it seems ok.
> The output maps is all 0s, with only one cell (close to the point I
> chose, but not on it) with value 1.

AFAIU r.water.outlet is extremely sensitive to local variations of 
terrain. Check the drainage direction map close to your point to see 
whether the resulting watershed is coherent with these directions.

I don't know if r.fill.dir on the DEM before calulating the drainage 
directions might help ?

Moritz