Barometric Efficiency

Abstract

Abstract The barometric efficiency is used to describe how water levels in wells fluctuate in response to atmospheric pressure. Normally, water levels rise whenever the barometric pressure falls, and vice versa. This phenomenon is observed in both confined and in deep, unconfined aquifers. In confined aquifers, the change in water level is caused by a change in the force applied to the Earth's surface by the atmospheric pressure—higher atmospheric pressure causes a greater load, which is transferred to water at depth, causing the water pressure within the aquifer to rise. In unconfined aquifers, the response is because of the difference in air movement through the borehole vs. the unsaturated zone, resulting in a rapid change in water levels in an open borehole, followed by a slower change to the original level once the air pressure at the water table equals the air pressure in the borehole.