Rising sea levels threaten coastal infrastructure integrity worldwide

Rising sea levels are causing coastal groundwater to ascend, making it saltier and more corrosive. This phenomenon is placing global underground infrastructure at risk, according to a new study from the University of Hawai'i at Manoa. The study reveals that critical systems such as sewer lines, roadways, and building foundations are increasingly vulnerable to corrosion and structural failures.

Shellie Habel, the study's lead author and a coastal geologist at the School of Ocean and Earth Science and Technology (SOEST), explained, "The rising of groundwater due to sea level increase is a well-known factor in potential chronic flooding. However, its early interaction with buried infrastructure, causing significant damage, tends to be ignored in many planning processes."

Researchers have pinpointed 1,546 coastal cities and towns globally, inhabited by approximately 1.42 billion people, where buried infrastructure is particularly at risk. This identification was possible through the use of global elevation and geospatial data mapping urbanization levels.

Chip Fletcher, study co-author and interim Dean of SOEST, highlighted the findings from the IPCC's 6th Assessment Report, which confirms the long-term inevitability of sea level rise. "This calls for immediate redesigning of communities to enhance resilience and equity," Fletcher noted.

Before surface flooding becomes apparent, rising sea levels are already affecting the subsurface by enhancing the corrosiveness of the environment surrounding buried infrastructures. This process can lead to compromised drainage and sewage systems, and weakened building foundations, significantly mobilizing urban contamination.

"The impacts of sea-level rise on coastal groundwater are largely out of sight and thus often out of mind when it comes to infrastructure management," added Habel, who also works with the Climate Resilience Collaborative (CRC) and Hawai'i Sea Grant at SOEST.

The study not only outlines the current problems but also aims to guide future infrastructure management and adaptation strategies, ensuring more effective resilience against the impacts of rising sea levels.

Research Report:Hidden Threat: The Influence of Sea-Level Rise on Coastal Groundwater and the Convergence of Impacts on Municipal Infrastructure