R. Maliva, K. Coulibaly, W. Guo, T.M. Missimer
Ground Water, 49, no. 2, 1-3, (2011)
Groundwater withdrawals are limited in many areasbecause of concerns over impacts to shallow unconfinedaquifers and hydrologically connected surface water sys-tems. Concurrent declines in the potentiometric surfacesof unconfined aquifers and underlying confined aquifers are frequently assumed to be due to leakage of water from the former to latter, especially where the confined aquifer
is much more heavily exploited and the hydraulic gradient is downward. It has long been known that changes in pressure at the land surface or in shallow aquifers can be transmitted downward to underlying confined aquifers.Meinzer noted that “artesian wells are likely to have large fluctuations that are due to pressure effects not related to replenishment from the surface.” A textbook example of the phenomenon is fluctuation inthe pressure in confined aquifers caused by the weightof passing railroad trains .Other surficial processes that can impact confined aquiferheads include barometric pressure, tides, and water loading .