Researchers have recently identified a hazard lurking in coastal regions that wreaks havoc on crucial infrastructure before it is detected.
What's happening?
Earth scientists at the University of Hawai'i at Mānoa published a review in January in the journal Annual Review of Marine Science that detailed a "hidden threat" to municipal infrastructure: coastal groundwater.
The dangers it poses have been fueled by rising sea levels, which push it closer to the surface, increasing its salinity and corrosiveness.
Why is shallowing groundwater concerning?
Those characteristics of shallowing groundwater threaten the structural integrity of completely or partially buried infrastructure — including drains, sewers, potable water lines, roadways, and building foundations — years before flooding ever does.
"While it has been recognized that shallowing groundwater will eventually result in chronic flooding as it surfaces, what's less known is that it can start causing problems decades beforehand as groundwater interacts with buried infrastructure," Shellie Habel, lead author and coastal geologist at UH Mānoa, told Phys.org.
"... The damage caused by sea level rise-influenced coastal groundwater is often concealed and not immediately perceptible."
The researchers collected preliminary analysis using a global elevation dataset and found that 1.42 billion people across potentially 1,546 functional urban areas worldwide are susceptible to this problem.
Rising sea levels could be especially problematic along the eastern seaboard, where states such as the Carolinas, Florida, and Louisiana may look geographically different by the end of the century. Internationally, countries including Singapore and Indonesia are facing similar challenges.
What's being done about the shallowing groundwater?
The team from UH Mānoa began this research to raise awareness and disseminate suggestions, such as installing groundwater monitoring networks and generating simulations that consider multiple flood sources, from world experts to analyze the risks and damages associated with shallowing groundwater and to improve adaptation and management strategies.
Meanwhile, some companies have created floating houses to help combat the issue.
"Being aware of these hidden impacts of sea level rise is of significant importance for the State of Hawai'i due to the concentration of communities situated along low-lying coastal zones where groundwater is generally very shallow," Habel said.
"The IPCC 6th Assessment Report tells us that sea level rise is an unstoppable and irreversible reality for centuries to millennia," said Chip Fletcher, study co-author and director of the school's Climate Resilience Collaborative. "Now is the time to prepare for the challenges posed by this problem by redesigning our communities for greater resilience and social equity."
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