Ian,
You might be able to use r.watershed (under raster/hydrologic modeling/watershed analysis) to do this. Input your raster of rainfall accumulation as flow accumulation per cell. Then look at the accumulation output. It should be in the same units as your rainfall inputs and should show you the amount of water that accumulates per cell from rainfall and upslope runoff combined. If you convert this to water depth per cell (it may already come out this way depending on your input), you can see how much flooding there is in each cell.
Michael
____________________
C. Michael Barton
Director, Center for Social Dynamics & Complexity
Professor of Anthropology, School of Human Evolution & Social Change
Arizona State University
voice: 480-965-6262 (SHESC), 480-727-9746 (CSDC)
fax: 480-965-7671 (SHESC), 480-727-0709 (CSDC)
www: http://www.public.asu.edu/~cmbarton, http://csdc.asu.edu
On Aug 5, 2011, at 9:00 AM, <grass-user-request@lists.osgeo.org> <grass-user-request@lists.osgeo.org> wrote:
Date: Thu, 04 Aug 2011 20:36:51 +1000
From: Ian Willis <Ian.Willis@checksum.net.au>
Subject: [GRASS-user] Ability to model flash flooding
To: GRASS user list <grass-user@lists.osgeo.org>
Message-ID: <1312454211.1978.42.camel@thorium>
Content-Type: text/plain; charset="UTF-8"Hi All
To learn how to use grass I've been trying to solve a real world
problem. The problem that I chose was the flash flooding which occurred
in south eastern Queensland. I'd like to see if grass could have
provided reasonably accurate predictions and see if it could be used as
a warning system.Ideally what I'd like to do is use the archived radar rainfall
information from http://www.bom.gov.au/products/IDR503.loop.shtml#skip
which can be found on http://gw.barratt.com.au/radar/IDR503/2011/01/10/I am intending extrapolate the rainfall rate using the Z value
conversions recommended for east coast lows as per
http://www.catchment.crc.org.au/pdfs/technical200207.pdfand then convert the rainfall rate rasters to the resolution of the
aster dem.I believe that the CASC2D module was used for this process as aluded to
in
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.20.318&rep=rep1&type=pdf however it doesn't appear to be available in the current version of grass.
I was contemplating seeing if I could make it work however before
muddling along any further I thought that I'd ask for a bit advice. To
say the least I'm learning a lot about using grass but my knowledge is
still quite basic.
My background is on unix/linux systems so I find the environment
reasonably comfortable.
Any thoughts would be appreciated.Cheers Ian