There is no one model. And in many aquifers no one much knows where or how water moves. So long as it's there to be tapped it's ignored.

The aquifers that are better modeled are the ones that have problems affecting the people using them. Regionally here that's the Odessa - overtapped for irrigation. Several underlying the Hanford site - contaminated with radioactive and chemical waste threatening a city's wells. And in the 1000 springs aquifer in Idaho - where aquaculture, agriculture and river flow needs for salmon collide.

There is a pretty good idea of where a liter of water dumped onto the ground is going to go, how long it's going to take to get there in those places.

But each one has entirely unique hydrology and geology. Their models don't interchange.