- September 1, 2021: Vol. 8, Number 8

Immovable objects: Flood-prone cities considering seawalls to protect property, infrastructure

by Mike Consol

With sea levels on the rise and storm surges more frequent and violent, several U.S. cities are considering a medieval solution to the problem in their quest to protect real estate properties and infrastructure: seawalls.

Currently, Charleston, S.C.; the Houston/Galveston metro area; Miami; and New York City are mulling their options. Many other U.S. cities might follow, considering that a 2017 study by the Union of Concerned Scientists, which assessed chronic flooding risks in 52 large coastal cities, found that by 2030, the 30 cities most at risk can expect at least two-dozen tidal floods yearly on average. The study defined tidal flooding as seawater encroaching into at least 10 percent of a city. Cumulatively, the at-risk cities are home to about 6 million people, and the study projected that by 2045, most of them will experience more than 100 days of flooding annually.

This flooding won’t just become more frequent, it also will become deeper, extend farther inland and last longer as sea levels continue to rise, according to Gary Griggs, director of the Institute of Marine Sciences and a professor at the University of California, Santa Cruz. Greater encroachment will cause increasing harm to infrastructure, development and property.

The problem with pursuing a seawall solution are manifold, says Griggs, director of the Institute of Marine Sciences and a professor at the University of California, Santa Cruz. Large-scale seawall proposals raise important long-term questions that residents, urban leaders and elected officials at all levels of government need to consider carefully before they invest billions of dollars, he writes in an article published by The Conversation, an independent nonprofit news organization.

“This approach is almost certainly a short-term strategy that will protect only a few cities and will protect only selected portions of those cities effectively,” writes Griggs.

Among the key issues signaled by Griggs are:

  • Who and what will be protected by these large walls, and at what cost? For example, New York City has a 520-mile coastline, but seawall proposals there focus only on protecting lower Manhattan.
  • How many years of protection might these barriers provide?
  • Do people really want to live behind walls? In New York, Miami and elsewhere, residents have objected to flood walls that would block their vistas.
  • Who will pay for the seawalls? Proposing multibillion-dollar walls is one thing, but where will the funds come from to actually construct and maintain the massive structures? In Texas, where the proposed “Ike Dike” across Galveston Bay is projected to cost some $26 billion, the state legislature is considering creating a special flood-control district with the power to levy property taxes within its boundaries to raise the state’s share.

In the long run, writes Griggs, there is no way to hold back the Atlantic Ocean.

Read his full report at this link:


Mike Consol ( is editor of Real Assets Adviser. Follow him on Twitter @mikeconsol to read his latest postings.


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