3D groundwater flow models
Generally the McDonald-Harbaugh modflow with contaminant transport modules. It's a good research tool, but less applicable in the real world than people thought because we can never get enough subsurface data to accurately represent the system. There are just too many heterogeneities. (Good for water supply models as averaging is necessary in those applications).

Some scientists are also pricks though (but not geologists).
(MichaelS wasn't picked again, Wed 20 Jan 2010, 12:12, 1 reply, 16 years ago)

I've only used very basic small scale things for groundwater
and not very often. That's the trouble with modelling, it'd be much more accurate to just measure what is actually happening...
( Vipros. clever got me this far, then tricky got me in, Wed 20 Jan 2010, 12:14, Reply)

Exactly. We are getting away from modeling in many cases and going for real world measurememts/.
I'm involved in a group that is going to be publishing a document on mass flux measurements (ways to do it and how to use the data). If you are interested I'll email you a copy in March when the final copy should be out.
(MichaelS wasn't picked again, Wed 20 Jan 2010, 12:28, Reply)