Published in the peer-reviewed journal Water, Air, & Soil Pollution, the study examined long-term changes in chloride—an indicator of saltwater intrusion—in groundwater wells near Guam's coastline. The findings suggest that accelerating sea-level rise may be contributing to increased salt levels in some of the island's drinking-water wells.

The research was led by Dr. Barry Kim, Associate Professor of Water Engineering at the University of Guam Water and Environmental Research Institute of the Western Pacific (WERI), and Dr. Byoungyong Lee, Associate Professor of Computer Science, together with collaborators from partner institutions. The project used long-term groundwater monitoring data provided by the Guam Waterworks Authority and received support from NASA Established Program to Stimulate Competitive Research (EPSCoR)  and the U.S. Geological Survey.

Guam relies almost entirely on groundwater for its drinking water. Freshwater is stored in underground aquifers that rest above seawater, making them particularly vulnerable to rising ocean levels. As sea levels rise, saltwater can move farther inland, increasing chloride concentrations in groundwater wells.

Previous research by WERI has shown that approximately 70% of Guam's production wells have experienced increasing chloride levels since the 1970s, with some exceeding the secondary drinking water standard established under the Safe Drinking Water Act. While scientists have long documented this trend, identifying its causes has been challenging because groundwater is influenced by many factors, including pumping rates, land development, drought, storms, and climate change.

To better understand those complex interactions, the research team analyzed more than 40 years of groundwater monitoring data from two Guam Waterworks Authority production wells in the Finegayan area. Using AI, the researchers examined how chloride levels changed over time and identified patterns that would have been difficult to detect using conventional analytical methods.

The team then compared groundwater records from before and after the early 1990s, when sea-level rise in Guam began accelerating, according to long-term tide-gauge measurements. The analysis found that one of the two wells, located closer to the coast, exhibited a noticeable shift in chloride patterns after 1993, suggesting that rising sea levels may be playing an increasingly important role in saltwater intrusion.

"Our goal was to better understand the factors contributing to increasing chloride levels in Guam's groundwater," Kim said. "AI allowed us to analyze long-term data in a new way and identify patterns that may not be apparent using conventional methods."

While additional research is needed, the findings provide new evidence linking climate-driven sea-level rise to changes in Guam's groundwater quality. The researchers say the results can help inform future water management decisions, including where new wells are developed and how existing wells are managed as climate conditions continue to change.

The study also demonstrates how emerging technologies can strengthen environmental research and help address issues that directly affect island communities. As climate change continues to reshape Pacific island environments, the researchers hope their work will provide information that supports the long-term protection and sustainable management of Guam's freshwater resources.

For more information about the study, visit: https://url.uog.edu/nVDyuy.

University of Guam researchers use artificial intelligence to help uncover long-term changes in the island's drinking water supply