r.watershed mods

[James Darrell McCauley]

I've been asked to modify r.watershed and thought it would be a good
idea to ask the public about this before I reinvent anything.

For each cell in an accumulation map, my client wants to know how much
came from each landuse in the watershed.  Say we have 3 landuses: A,
B, C. Then in r.mapcalc parlance,
    accumulation_map=A+B+C
Has anyone done something like this? It would require adding
an additional command line option (landuse=) and would create more
(potentially a large number of) output files (depending upon
how many landuses are present).

I'm completely unfamiliar with r.watershed (am running cflow now).
Can anyone make any recommendations as far as starting points?

BTW, r.basins.fill mentions a tutorial for r.watershed:
>     See Appendix A of the GRASS Tutorial: r.watershed for
>     further details on the combined use of r.basins.fill and
>     r.watershed.
Does this exist? Where?

--Darrell

James Darrell McCauley, USDA National Needs Fellow
Agric Engineering, Purdue University, West Lafayette, IN 47907-1146, USA
mccauley at ecn.purdue.edu    +++   http://soils.ecn.purdue.edu/~mccauley/

P.S. Anyone have an email address for Dale White, Dept. of Geography, 
The Pennsylvania State University. He worked on r.basins.fill along
with Larry Band and may know the whereabouts of the tutorial.