UH study: Rising seas eating away at underground infrastructure in Hawaiʻi, globally

New research out of UH Mānoa finds rising seas are eating away at infrastructure in low-lying areas like sewer lines, roadways and building foundations around the globe including in Waikīkī.

This study by Earth scientists at the University of Hawaiʻi at Mānoa was compiled from research from experts worldwide.

According to the study, led by UH coastal geologist Shellie Habel, cities with buried infrastructure are most at risk for corrosion and system failures due to interaction with this shallower and saltier groundwater.

“Salty groundwater is likely interacting with these really corroded elements and it’s corroding this infrastructure in a way that folks aren’t keeping an eye on,” Habel said, who works at the UH Mānoa School of Ocean and Earth Science and Technology. “You can’t see it, you can’t see it happening, but we need to start paying attention.”

Researchers say the UH study underscores the urgency for increased attention and research into strategies to adapt and develop future construction plans.

“The fact that this water coming up isn’t clean in a lot of cases, you know, sometimes it’ll have septic waste in it, like sewage waste in it,” Habel said. “Sometimes it’ll have contaminants from old industrial practices from long ago.”

With the study, the research team aimed to create awareness about these issues and offer guidance from world experts on managing them. Habel and co-authors reviewed existing literature to examine the diverse effects on different types of infrastructure.

Additionally, by employing worldwide elevation data and geospatial data that indicate the extent of urban development, they identified 1,546 low-lying coastal cities and towns globally, where around 1.42 billion people live, that are likely experiencing these impacts.

“Being aware of these hidden impacts of sea-level rise is of significant importance for the State of Hawaiʻi due to the concentration of communities situated along low-lying coastal zones where groundwater is generally very shallow,” said Habel.

Chip Fletcher, study co-author, interim dean of SOEST, and director of the UH Mānoa Climate Resilience Collaborative (CRC), said the IPCC 6th Assessment Report shows that sea-level rise is an unstoppable and irreversible reality for centuries to millennia.

“Now is the time to prepare for the challenges posed by this problem by redesigning our communities for greater resilience and social equity,” he added.

CRC actively collaborates with partners across the nation and infrastructure managers in Hawaiʻi to gain a comprehensive assessment of how vital infrastructure, encompassing pipe networks, roadways and buildings, is impacted. Understanding the impacts and risks associated with sea level rise-influenced coastal groundwater enables more effective management and adaptation.