Study: Almost 14% of Our Coastline is Now Covered in Concrete

As of 2015, almost 14% of U.S. shoreline is covered in concrete.

Researchers working with data from the National Oceanic and Atmospheric Administration found that up to 22,842 kilometers of the country’s coast is “armored” with concrete barriers and seawalls, and that includes ocean, bay, and tidal river shorelines. Concrete installations can easily last up to 50 years, and the scientists say that unless trends change, they expect the amount of new concrete on our coasts to at least double this century.

One of the lead researchers behind the new study was Rachel K. Gittman of Nahant, Maryland. She and her fellow scientists concluded:

“The demand for coastal defense strategies against storms and sea-level rise (SLR) has increased with population growth and development along coastlines. Shoreline hardening, a common defense strategy that includes the use of seawalls and bulkheads, is resulting in a ‘coastal squeeze’ on estuarine habitats.”

That confirms findings from other scientists and environmentalists in the Chesapeake Bay region. In the National Wildlife Foundation’s report on “Sea-Level Rise and Coastal Habitats of the Chesapeake Bay,” scientists found that such seawalls and dikes posed a serious threat to local marine life habitats. If sea levels rise in the 21st century, as most scientists agree that they will, then concrete barriers and seawalls can prevent coastal habitats from naturally migrating inland with rising tides.

The NWF wrote, “We may be able to preserve habitats in some areas by restoring natural replenishment of sediments, for example, by removing seawalls…or reconsidering the use of river dams.”

Communities looking for an alternative to artificial, armored sea walls can encourage the replenishment of natural “living barriers,” which include vegetation planting or offshore breakwaters. But that might be a hard sell for developers in the South Atlantic and Gulf States, where the bulk of new concrete seawalls are installed. Although living barriers might benefit marine habitats, the effectiveness of living barriers in protecting human habitats has not been extensively studied.

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