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Coastal wetlands are a powerful weapon against flooding

A new study from Swansea University reveals that coastal wetlands provide even more flood protection than previously realized. Beyond filtering water and creating habitats for fish, coastal wetlands protect coastal communities from flooding. 

The experts used computer simulations to demonstrate that wetlands located in estuaries, such as salt marshes, can reduce flooding levels by up to two meters. The projections also show that these types of wetlands provide protection far inland up estuary channels.

According to the researchers, the simulated benefits they observed could save up to $38 million in avoided flood damage costs per estuary during a large storm.

The research is particularly relevant today as urban development poses increasing threats to coastal wetlands. At the same time, 22 of the world’s largest 32 cities – including London and New York – are built on low-lying land around estuaries. 

Flooding is a growing threat to low-lying cities as climate change ramps up the intensity and frequency of storms.

“Our study shows that coastal wetlands play a crucial role in reducing storm-driven flooding in estuaries. They are nature’s flood defenses and we need them now more than ever,” said Dr. Tom Fairchild.

Previous studies have focused on wetlands along open coastlines, where the plants absorb wave energy and help keep waves from pushing inland. 

The experts found that coastal wetlands play a much bigger role in storm flood prevention. In addition to absorbing wave energy, these wetlands reduce storm surges as they move up estuary channels.

“Our work shows that when big storms hit, nature works extra hard for us, preventing or reducing coastal flooding for free,” said study co-author Dr. John Griffin. “The upshot is, by protecting and restoring coastal wetlands, we help protect ourselves from the growing threat of flooding. It’s a no-brainer.”

The study is published in the journal Environmental Research Letters.

By Chrissy Sexton, Staff Writer

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