Published Article on Karst Aquifer Recharge Timescales in Guam

The manuscript entitled “Analyzing Recharge Dynamics and Storage in a Thick, Karstic Vadose Zone” by Patricia Spellman, Charles Breithaupt, Paul Bremner (ST13), Jason Gulley, John Jenson, and Mark Lander has been published in the Water Resources Research (AGU) Journal (http://doi.org/10.1029/2021WR031704). The article is about quantifying the rate, timescale, and magnitude of water storage within an aquifer in northern Guam.

Bremner contributed methodology, specifically signal analysis techniques and the use of transfer functions to this work. The results quantified the rapid recharge (measured in hours) to the aquifer after rainfall events and the slow recharge that follows over one or more months. The new method used will help hydrological modeling in karst systems.

Below is the Plain Language Summary: “Recharge is a critical component of water resource allocation as it governs the availability of water for public, agricultural, and industrial supply. Therefore, understanding how precipitation becomes recharge to the aquifer is an important step in water resource management. However, in young, minimally evolved (eogenetic) karst that maintain significant primary porosity, appreciable vadose storage may occur. In island settings where water resources are volatile, the timing of precipitation to recharge significantly impacts groundwater stores and water resource allocation. We develop transfer functions between precipitation and recharge and use analytical methods to quantify (a) timescales of vadose storage, (b) estimates of storage and (c) magnitudes of recharge in a thick, karst vadose zone on Guam. Our work aligns with previous observations and provides a new method to estimate storage and transport through the vadose zone to karst aquifers.”

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