Imagine you just purchased a waterfront property and you’re worried about the effect of erosion on your shoreline.
What do you do? Install bulkheads, perhaps? Maybe riprap or stone revetments?
It turns out there’s a better method – one that naturally protects shorelines from erosion while fostering habitat development for native species.
They’re called “living shorelines,” and numerous projects across the state have led to the creation of these natural protective barriers.
Lewes’ newest living shoreline was introduced Thursday by the Delaware Department of Natural Resources and Environmental Control, the U.S. Fish and Wildlife Service and the Delaware Living Shorelines Committee.
The project, located behind the little league fields at the Lewes Canalfront Park and Marina, resulted in a 180-foot extension adjacent to an already existing living shoreline constructed in 2014.
Here’s how a living shoreline works:
Using plants, sand or rock, living shorelines protect and stabilize coastal edges because they do not impede the growth of plants and animals like concrete or hard structures do, according to the National Oceanic and Atmospheric Administration. Living shorelines grow, meaning protection becomes stronger with time.
“Traditional methods of shoreline protection, such as bulkheads and riprap, can actually make erosion problems worse by redirecting wave energy. In addition, they disconnect the land from the water which prevents wildlife, such as turtles and ducks, from accessing the habitats they need to survive,” the Delaware Living Shorelines Committee explains on their website.
According to DNREC, living shorelines are referred to as a type of “soft” infrastructure because they can adapt to a changing environment while also being strong.
“Hard infrastructures, such as bulkheads or retaining walls, cannot change depending on the season, weather or other conditions,” says a DNREC website. “Instead of an abrupt drop-off from land to water, living shorelines create a gentler slope which connects plants and animals to the water. The softer materials are also able to absorb wave energy and reduce flooding during hurricanes and storms. Hard structures deflect strong wave energy, causing below water scouring, structural damage, and even shoreline erosion downstream.”
The new portion of the Lewes living shoreline uses natural materials: a small amount of coconut fiber coir logs and 1,300 recycled oyster shell bags. It was completed by a team of 13 volunteers in just one day in June.
Netted oyster shell bags, carefully arranged in wavy pyramid formations along the intertidal zone, are filled with recycled oyster shells from restaurants in Wilmington.
The bags reduce wave energy and allow wetland habitat restoration. The design includes breaks in the structure to allow tidal exchange, fish and fauna passage and runoff outflow.
Live oysters colonize on and near the shell bags, filtering the water and fertilizing plants while providing additional protection against tides and waves.
As high-tide turns to low, sediment becomes trapped behind the coir logs and oyster bags, where it accumulates over time. With enough sediment, the conditions become perfect for wetland grass to grow and ribbed mussels to populate.
According to the Partnership for the Delaware Estuary, within marshes of the mid-Atlantic region ribbed mussels collectively outweigh all other animals combined.
“Like many bivalve shellfish, they are referred to as ‘ecosystem engineers’ because they have the ability to build their own habitats and transform the landscape for other species.,” according to the Partnership. “They can form clusters as dense as hundreds per square meter. Ribbed mussels bind to the roots of vegetation, which helps to hold the marsh together. The mussels filter food from the water and fertilize marsh plants. As the plants grow, they trap sediment, helping the marsh grow vertically.”
The result is a visually appealing, environmentally friendly and sustainable solution to the problem of erosion.
As an added benefit, by slowing erosion, areas with living shorelines require less frequent dredging.
“Living shorelines are an innovative and environmentally friendly alternative that uses natural materials such as oyster shells,” said DNREC Secretary Shawn Garvin. “This project is a good example of the benefits living shorelines provide: pollutant filtering to improve water quality; habitat for animals, fish and birds; and protection from erosion and of infrastructure; as well as aesthetics for property owners.”
These living alternatives also help reverse the unfortunate trend of coastal marsh destruction.
“From fisheries and water quality to flood protection, the ecological health and resilience of the Delaware Estuary depends on our historically abundant coastal marshes, but sadly we are losing about an acre per day,” said Kathy Klein, executive director at the Partnership for the Delaware Estuary. “Thanks to its science-based design and monitoring, this project showcases how innovative, nature-based tactics can help stem these wetland losses.”
Lewes mayor Ted Becker said that the new living shoreline provides the city an opportunity to “further enhance our resilience as we look at sea-level rise and climate change.”
“Not only is this a great habitat for all the animals and wildlife, but also it’s actually a beautiful sight as you’re travelling the canal,” Becker said.
In addition to public projects such as the newly completed one in Lewes, the Delaware Living Shorelines Committee is lobbying private property owners to install or convert to natural alternatives.
The cost of installation and maintenance is, on average, less than conventional methods. Because nature takes care of most of the work, living shorelines can be initiated in a matter of a day or less.
Nature has already stepped in to help complete the Lewes project. Sediment levels have increased significantly in the month since installation and oyster colonies have begun forming nearby.
If you own a waterfront property and would like to learn more about how you could develop a living shoreline, got to the Delaware Living Shorelines Committee’s website.
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