It seems the easiest way to speed this up is to parallelize it, which can be done fairly easily with GNU parallel. https://grasswiki.osgeo.org/wiki/Parallelizing_Scripts#GNU_Parallel
On Sat, Feb 11, 2017 at 8:12 AM, Ken Mankoff <[email protected]> wrote: > Hi GRASS list, > > I have a watershed raster with 200 million cells. I calculate the basins > and the baseline accumulation (i.e. flow=1) and have done so with > r.watershed like this: > > r.watershed -a elevation=e drainage=d accumulation=a basins=b > threshold=50000 --q > > That takes ~2 minutes. > > I now need to calculate surface flow ~1000 times over this same watershed > (every day for 3 years). That would take 1.5 days which is not > unreasonable. But is there a faster way? Can I use the pre-computed basins > and accumulation rasters? Is it faster to loop over the basins (there are > ~1000 of them)? Or do I just run the entire command as above 1000 times but > with variables for flow= and accumulation=? > > Thanks, > > -k. >
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