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Wetlands Can Protect Against Floods

Wetlands, also known as marshes or bogs, cover about six percent of the land in the contiguous American states, and are considered one of the most productive ecosystems in the world. According to the Environmental Protection Agency (EPA), wetlands are areas of land covered by water for long periods of time. Every year, wetlands convert tons of biomass into detritus, a special substance that aquatic insects, shellfish and fish consume. They also support one-third of the world’s endangered species population, contain valuable foods such as fish and oysters, and are integral to global water and nitrogen cycles.

Wetlands also have the unique ability to slow the momentum of floods, or stop them altogether. They do this by absorbing water and dispersing wave energy, thus acting as natural breakwaters. In 2011, Hurricane Irene hit North Carolina, a state with many estuarine marshes. The two-meter-high concrete bulkheads residents placed outside their homes were severely damaged by the storm, but the sediment levels of surrounding wetlands remained intact. In fact, a year later, the marsh’s vegetation had regrown entirely. Michael W. Beck, a research professor at the University of California, has discovered that wetlands in New York and New Jersey during Superstorm Sandy prevented $625 million of flood damage. Not only do wetlands serve better than cement barriers, but they are also cheaper to construct and preserve.

However, over 386 thousand square miles of American wetlands have been filled, dredged, or drained since 1780, when mass colonization in the area began. Today, most states have lost over half their wetland space, and some have only ten percent left. Not only this, but many of the remaining wetlands “are disintegrating as higher seas, stronger storms and runaway development trigger an epidemic of erosion and flood damage,” according to Scientific American. “Every day waves bite off another 89 hectares of the country.” Flooding and erosion are some of the more disastrous effects of climate change, which continues to impact coastal cities around the world. Washington, D.C., once a continuous wetland, has now been almost entirely redeveloped. In some cases, soil eroded from intensified storms and higher seas has had to be replaced through land reclamation. Damage to wetlands is a clear example of how climate change has already begun to impact humans, even those very near us.

One possible solution to this problem is wetland restoration. Research suggests that marshes can be ‘custom-built’ to fit and protect certain zones, but they must still follow natural growth patterns. For example, when an early marsh-restoration initiative planted aquatic weeds short distances away from each other to eliminate competition, the vegetation grew very slowly. Brian Silliman, an ecologist at Duke University, says that “when marsh plants are together, they share oxygen, so their growth rate is twice as high.” To imitate seeding patterns, grasses rooted together can have up to three times their regular growth rate. The addition of blue crabs and sea snails, natural components of the marsh ecosystem, increases the plants’ chance of survival even more. Another test proves that underwater barriers, called berms, support the habitat’s oyster population and protect against erosion. Studies even suggest that using a combination of levees and wetlands in more urban areas could be beneficial. These experiments show that there is hope left for wetlands and the essential role they play in flood protection.


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