Collaborative Research: The role of temporally varying specific storage on confined aquifer dynamics

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Access to clean drinking water continues to be a growing concern as climate change, population growth and industrialization increase the prevalence of water scarcity. In response to dwindling surface water supply, many regions turn to water from porous rocks or sediments known as aquifers that hold most of the world’s liquid freshwater. Confined aquifers, which are typically deep and pressurized, hold the majority of freshwater in the world’s aquifers. Predicting whether water storage in a confined aquifer will increase, decrease, or remain constant given variations in human activity such as pumping, and climate change is critical for preserving aquifers for future use, but has been challenging to estimate. Changes in confined aquifer storage are typically estimated by a parameter known as storativity, which is obtained by multiplying changes in water levels measured in wells. In this project, the researchers will determine how storativity changes over space and time, and how accurate estimation of storativity can help scientists and engineers to accurately estimate aquifer storage, and improve our ability to effectively manage groundwater use. In confined aquifers, storativity can vary significantly over time, leading to inaccurate predictions in traditional groundwater models if the storativity is assumed constant. The compaction of clay layers, which can be observed from satellites, causes changes in storativity. If clays are present, assuming that storativity is constant can lead to overly optimistic estimates of aquifer recharge which, if implemented in management practices, could result in rapid aquifer depletion. In this research, the investigators will develop groundwater models for the Parowan Valley in Utah, a region with well-constrained groundwater use, and that shares similarities with other high-use aquifers of the world. They will develop two types of models, (1) traditional models that assume constant storativity, and (2) more robust models that allow storativity to vary with time and compare the model performance against well measurements and satellite data. Through this research, scientists will quantify the effect that time-varying storativity has on aquifer storage, and contribute to improving estimates of recharge and aquifer parameters such as hydraulic conductivity. During the project, they will collaborate and work with community stakeholders, and train graduate and undergraduate students in both research and science communication.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.