Year: 2026
Type: preprint
Abstract: While most managed aquifer recharge (MAR) efforts focus on deep groundwater systems, this study introduces micro-scale managed aquifer recharge (µMAR). This approach investigates water storage potential in shallow hydrogeological units, where the water is more readily recoverable. Where viable, this approach can avoid the need to construct or expand farm-scale reservoirs which reduce the farming footprint and are subject to high evaporative losses. Towed Transient Electromagnetic (tTEM) surveys at the UC Merced Experimental Smart Farm revealed a coarse-grained pocket extending to a 15m depth, underlain by a thick low-resistivity layer separating this shallow zone from the deeper regional aquifer (45m depth). To test whether this shallow zone could serve as a viable water storage unit, we designed complementary recharge experiments using two basin configurations. This work focuses on one basin, located over existing coarse material with connectivity between the surface and the 15-meter target zone. A 15-meter monitoring well was installed within the coarse-grained pocket to continuously monitor groundwater levels. Prior to starting recharge experiments, pressure transducers at the monitoring well documented pre-existing groundwater (~4m of head), confirming the presence of a shallow aquifer or perched layer. Recharge experiments demonstrated rapid transducer response at the monitoring well: roughly 48 hours from initial infiltration. High-frequency (15-minute) water level data from a stilling well within the recharge basin and the monitoring well were used with site lithology to analyze the recharge using a HYDRUS 2D model, providing detailed insights into infiltration dynamics, lateral flow patterns, and a stronger basis for estimating recharge efficiency. Preliminary results demonstrate that the µMAR approach can produce a rapid aquifer response, with the shallow hydrogeological unit gaining significant storage during a few days of flooding. The µMAR approach could transform water management strategies in regions with similar shallow coarse-grained deposits, providing enhanced and more autonomous water security for land managers through distributed µMAR systems that reduce dependence on deeper regional aquifers.
Institution: University of California, Merced
Subfield: Environmental Engineering
Field: Environmental Science
Domain: Physical Sciences
Open Access status: gold
OpenAlex ID: W7124457260
Cites:
Cited by:
Related to: