Groundwater rise as result of climate change poses a significant threat to coastal cities, according to University of Rhode Island assistant professor of geosciences Christopher Russoniello. Russoniello and colleagues recently published a commentary piece highlighting hazards that are often overlooked in urban infrastructure.

Invisible Groundwater Threats to Coastal Urban Infrastructure, featured in the scientific journal Nature Cities, highlights three hazards in infrastructure that often go undiscussed: water table rise; groundwater salinization; and compound human-made and climate-related groundwater changes. The existence of these hazards underscores the critical need for better monitoring and solutions to ensure safe and sustainable urban environments, according to the paper’s authors.

Affected infrastructure include roads, sewers, and septic systems; buried methane and electric lines; and building foundations. Other types of urban infrastructure are vulnerable to corrosion from saltwater intrusion, including buried pipes and tanks.

“I think we have come to an understanding that groundwater plays a bigger role in surface flooding and other hazards facing urban communities than initially thought,” Russoniello said. “A lot of the previous work into groundwater near the coast is focused on more rural conditions, such as how groundwater rise will impact septic systems or how it will impact natural settings someplace like the southern coast of Rhode Island.”

Saltwater intrusion — the creep of seawater into private wells, freshwater aquifers, and septic systems — is a growing problem in Rhode Island. As sea levels rise, more frequent and intense rains fall and storm surge reaches farther inland, more wells and septic systems are being put at risk of contamination and inundation.

The problem of saltwater intrusion appears to be the most severe in Washington County, most notably Charlestown, South Kingstown, and Westerly.

Climate-related groundwater changes can impact a city’s capacity to protect its infrastructure, according to Russoniello. Groundwater rise and salinization under coastal cities can damage buried infrastructure, impair wastewater systems, reduce surface drainage, and render groundwater unsuitable for drinking.

Solutions could include incorporating corrosion-resistant pipes or concrete reinforcement in areas at risk; enhancing subsurface drainage or dewatering systems; and designing pumping well placement and extraction schedules that limit these challenges. There are opportunities to monitor groundwater levels and salinity dynamics by using geophysical surveys and multilevel wells instrumented with electrical conductivity and water pressure sensors.

“With the data we have showing how these changes can affect our aging urban infrastructure as climate is changing and sea levels continue to rise, I hope that this will be a call to action and a call to make positive change,” Russoniello said.

Russoniello is part of a team of researchers led by URI professor Emi Uchida studying flooding in the town of Warren. The multi-state collaboration also includes researchers in South Carolina and Delaware. Compared to sites in the other two states, Warren, which is more urban and doesn’t rely on groundwater or septic systems, is a perfect example of how potential climate-related groundwater hazards may go overlooked until they start to impact infrastructure.

Research findings could lead to updated guidelines and codes and use of materials that improve coastal urban infrastructure resilience to changing groundwater using nature-based or hard engineering based solutions.