7/1/2003 - 6/30/2004
- Timothy Eaton
The Cambrian-Ordovician aquifer has long been an important source of municipal water supply in SE Wisconsin, and pumping has drawn down the potentiometric surface of the deep aquifer system by over 400 ft during the 20th century. Regional flow modeling and limited well data suggest that static water levels may be locally below the base of the Maquoketa Formation, that forms the regional aquitard. The objectives of this proposal are 1) to investigate how unsaturated conditions might develop in a scaled physical sand-tank model, 2) to attempt to verify the development of such hydrogeologic conditions in the field, and 3) to predict the long-term impact on water supply and quality by observing the evolution of head in the vicinity of model pumping wells. Use of a physical sand-tank model presents an opportunity to investigate a phenomenon that is not commonly addressed by conventional computer flow models. Head data collected as unsaturated conditions develop in an appropriately-instrumented physical model will be useful for future specialized computer simulation of geochemical processes (PHREEQE-C) or saturated/unsaturated conditions (HYDRUS, SUTRA).