Changes in Gravity used to Quantify Groundwater-Storage Change in the Tucson AMA

The Tucson Active Management Area (AMA) is a semi-arid region in southern Arizona. Historically, groundwater pumping in the Tucson AMA exceeded recharge for many decades. Gravity-based methods developed by the USGS can be used to directly measure groundwater-storage changes, providing an estimate of total storage change that does not rely on uncertain estimates of inflows and outflows.