[GRASS-dev] r.terraflow flow direction rules

Hello,

I need to route VIC hydrological model, and the routing program read
AGNPS style flow direction.
I tried to run r.watershed on my srtm watershed, and after a week, I
just stopped it,
because I needed the PC for other processing.
(it was doing it, but slower and slower as it passed 60% in 3 days,
65% in 4 days etc...)

Now I am getting onto r.terraflow for flow direction,
but what i need is AGNPS output,
what is the flow direction type in r.terraflow format please.

Thank you
Yann

--
Yann Chemin
International Rice Research Institute
Office: http://www.irri.org/gis
Perso: http://www.freewebs.com/ychemin

Yann Chemin wrote:

I need to route VIC hydrological model, and the routing program read
AGNPS style flow direction. I tried to run r.watershed on my srtm
watershed, and after a week, I just stopped it, because I needed the
PC for other processing. (it was doing it, but slower and slower as
it passed 60% in 3 days, 65% in 4 days etc...)

FWIW, it could speed up again and also it could finish well before 100%.
It is slow but it gets there. (for trial and error method to find the
right threshold value, you might try at a low res first then scale?)

Now I am getting onto r.terraflow for flow direction,
but what i need is AGNPS output, what is the flow direction type
in r.terraflow format please.

r.terraflow uses MDF, see the pic in the r.terraflow help page and -s
flag.

for MDF -> dominant SDF, see the scripts in
http://trac.osgeo.org/grass/browser/grass-addons/raster/r.terraflow.tools/

if you don't use Matlab they can probably be made to work in Octave
without much trouble.

see d.rast.arrow's main.c for AGNPS format hints.

beware that r.terraflow sink-watershed output maps are not catchments
like you get from r.watershed.

Hamish

      ____________________________________________________________________________________
Be a better friend, newshound, and
know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ