On Wed, 17 Jan 2001 06:06:10 -0800 (PST), Mark Boris wrote:
I am not a modflow 'guru', but here are a few of my
findings resulting from attempting to use modflow
to model electric flow.Modflow96 compiles quite well under linux so I assume
that it also compiles well under other unices. The
egcs fortran compiler is what I used.
Great!
issue that you will run into though, is the size of
the data that you are planning to process. You must
change the size of the 'LENX' variable in the
modflow.f
source file to allow for a larger grid. But there is
a limit of how large you can practically make an input
dataset. I found that about 200x200x80 was about
the largest grid that would run in a reasonable amount
of time on a PIII800MHz with 512meg RAM. I would
suggest compiling modflow and making some dummy
datasets of approximately the same size as what you
would be using and see how long it would take to run.
Note that a model with many layers/inhomogenaities
takes longer to converge than a simple model.
That's why I was thinking of modeling the study area at various scales.
IMHO, use modflow96 since you can use free-formatted
input data files. If you have to convert GRASS files
to modflow files, you probably do not want to have to
worry about the fixed-fortran format required for
modflow88. Writing C apps or scripts to convert grass
files (or grass data exported to ascii) to modflow
should be pretty straightforward.
However, we must keep in mind that there is the problem of grid orientation and
variable grid size, which are necessary to accomodate geologic fabric
(heterogeneity and hydraulic anisotropy) and to improve convergence at
pumping wells or other groundwater sinks.
it myself yet. I am planning to investigate the
integration of grass with modflow/matlab/others over
the summer; I can let you know what I come up with
if you are still interested at that point.
I suspect that I will. Lets keep in touch.
Regards,
Rick
RG Hydro-Environmental Ltd.
WaterWatch ..... independent groundwater research
Richard Gagne, P.Geo., President
PO Box 25099
Halifax, NS Canada B3M 4H4
e-mail: rghydro@waterwatch.com
phone: (902) 457-7010
fax: (902) 457-3934