Researchers have thought about how storm surges and flooding from rising sea levels will harm the built environment along the coast, but what about the less obvious effects of climate change below the surface?
The hidden costs associated with building foundations due to sea level rise are examined in a new study by civil engineers at Colorado State University. They suggest a technique for inspection and repair to reduce the cost of deterioration brought on by saltwater corrosion.
It’s critical to plan ahead, according to the researchers from CSU’s NIST Center for Risk-Based Community Resilience Planning, especially with more than 16 million structures lining the Atlantic and Gulf coasts of the United States.
Hussam Mahmoud, a professor in the Department of Civil and Environmental Engineering and a co-author of the study, said: “This is a problem, and it’s going to cost a lot of money.”
One at-risk location
In Mobile County, Alabama, engineers looked at nearly 137,000 homes in low-lying areas and estimated how likely it was that the foundations would be damaged by saltwater corrosion.
As saltwater is more corrosive than freshwater, as the sea levels rises, so does the groundwater table. They estimated how long it would take for saltwater to get to the foundations of the buildings by using existing predictions for sea levels rise and water table levels based on wells in Mobile.
They estimated that by 2100, the annual repair costs for foundations in Mobile could reach $90 million under the direst sea levels rise scenarios.
The value we discovered for one of the saltwater intrusion scenarios is only applicable to 137,000 buildings in Mobile, which is significant, according to Mahmoud. The cost would be staggering if it were calculated for the entire East Coast or from the East to the West Coast.
Providing a solution
Based on the location of the building and the likelihood of saltwater corrosion, the engineers created a formula to assist building owners in deciding when to inspect and repair their structures. Building owners are said to save money by delaying foundation repairs until the proper time, but not until damage has already been done.
They also suggested using inexpensive sensors to guard against risks and keep track of the sea levels table close to a building’s foundation.
Mobile is an industrial port city with a sizable economically disadvantaged population, so the researchers decided to focus on it. They have started looking into how natural disasters affect Mobile’s most vulnerable neighborhoods so they can figure out the best way to help them in an emergency. This will help them figure out how to best use their resources.
Mahmoud said, “We have to have a good understanding of the impact of the hazard on the built environment in order for us to assess its social and economic impact.”
The team will then look at structural performance above and beyond the foundation and how that impacts locals. For example, how much wind and water surge can a building handle during a hurricane before it needs to be moved or sheltered?
Instead of waiting until something goes wrong, Mahmoud said, “This work will allow us to be proactive about finding solutions quickly to help those in need.”
The Center for Risk-Based Community Resilience Planning is a $20 million project led by CSU and involving more than a dozen other universities. Its goal is to help communities get back on their feet after natural disasters.
