r.watershed memory requirements!

[Markus Neteler]

On Mon, Sep 25, 2000 at 07:39:38AM -0700, David Finlayson wrote:
> I have a 23M DEM that I ran r.watershed on to try and
> calculate the flow accumulation (area weighted):
>  
>  r.watershed -m el=elv ac=flowacc
>  
> The process crashed after consuming all of the 1.7G of
> free space on my partition (in the .tmp directory of
> the mapset)!!  Everything worked just fine on a small
> elevation grid I had downloaded for a tutorial.  I had
> masked out the NULL areas (I think).  Any clues as to
> what is going on?  Is there an equivalent command to
> arc/info's flowaccumulation that is more space
> efficient?  How about the A^t search algorithm?  I'm
> not much of a number cruncher and haven't heard about this.
Hi David,

to calculate flow accumulation, try:
r.flow and
r.flowmd (multiple flow)
http://www.geog.uni-hannover.de/grass/gdp/html_grass5/html/r.flow.html
http://www.geog.uni-hannover.de/grass/gdp/html_grass5/html/r.flowmd.html

It is coming along with GRASS 5.

Hope this help

 Markus Neteler