r.watershed memory requirements!

[David Finlayson]

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.

=====
--
David Finlayson
david_finlayson at yahoo.com
University of Washington 
Box 351310 
Seattle, WA   98195 - 1310

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