Rich Shepard wrote:
On Wed, 10 Feb 2010, Micha Silver wrote:
A quick tip regarding r.water.outlet (you may have noticed this already)
The module creates a new raster covering the whole analysis region with
two possible values: 1 for all cells draining into the outlet, and 0
everywhere else. If you do r.to.vect straightaway, you?l get a vector
containing two polygons... I always run r.null setnull=0 on the
r.water.outlet result first. This insures that r.to.vect leaves you with
just the drainage area.
Micha,
I'm under a deadline to finish the current project, and nothing
seems to
be working correctly for me.
I just ran r.water.outlet using the drainage (aspect) map created by
r.watershed. The output is a yellow rectangle that the legend tells me
represents '0'; that is, there're no cells in the calculated basin.
The r.water.outlet module takes two parameters: first is the drainage
*direction* raster, which I usually create first with r.watershed, like:
>r.watershed elev=dem drain=flow_dir accum=flow_acc basin=basin
stream=str thresh=xxxx
(At this stage you can go and make popcorn...)
Next I do r.thin on the streams raster, and convert the thinned raster
to a line vector:
>r.thin str out=str_thin
>r.to.vect -s str_thin out=streams feature=line
Now you need the pour point which, as others have made abundantly clear
( ;-) ), must be exactly on a stream line. So zoom in *very* close to
the flooded house, and identify the X-Y coords on the stream just below
the house.
Now try:
>r.water.outlet drain=flow_dir basin=house_catchment east=xxx north=yyy
And finally the above trick to get your final vector drainage basin with:
>r.null house_catchment setnull=0
and
>r.to.vect -s house_catchment out=house_catchment feature=area
Good luck...
g.region -p reports:
projection: 99 (Lambert Conformal Conic)
zone: 0
datum: nad83
ellipsoid: grs80
north: 1334420
south: 1279150
west: 769190
east: 819260
nsres: 10
ewres: 10
rows: 5527
cols: 5007
cells: 27673689
The command line was:
r.water.outlet drain=aber10m.drain basin=lockie e=795542.95
n=1308323.52 --o
I can send copies of aber10m.drain and lockie. It makes no sense to me
that such a simple run fails to define the partial drainage basin. Any
help
or ideas you offer will be much appreciated.
Rich
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--
Micha Silver
Arava Development Co. +972-52-3665918
http://surfaces.co.il
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