Shoring up coasts against erosion
Living shorelines are the latest front in battle to control sediment loss, preserve habitat
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Some ideas get tested by fire, but a new idea about how to protect Bay shorelines with more natural buffering systems has been tested by water and hurricane-force winds and is helping to stem erosion and preserve nearby habitats.
“Living shorelines” is an increasingly popular approach to erosion control that uses strategically placed plants, stone and sand to deflect wave action, conserve soil and simultaneously provide critical shoreline habitat. Living shorelines often stand up to wave energy better than solid bulkheads or revetments, which add to the problem by amplifying waves on neighboring shores.
Jeff Opel, district manager of the Anne Arundel County Soil Conservation District in Maryland, saw dramatic evidence of this during Hurricane Isabel in 2003.
“We flew most of the county shoreline by helicopter shortly before the hurricane hit, and we flew it again about 90 days later. There was really significant damage along walls and bulkheads, and along riprap,” Opel said. “But when we looked at where we’d done nonstructural work, and at wetlands along the main front of the Bay, we saw very little damage to the shoreline itself. We were very surprised. It told us we were on to something.”
Living shorelines are most often used for areas with low– to medium-wave energy, and in many cases cost less than bulkheads and revetments. Unlike their more highly engineered counterparts, living shorelines prevent erosion without interrupting natural coastal processes or disrupting shoreline habitat.
A recent Bay Program report emphasized the importance of adopting such techniques to help meet habitat objectives, such as its goal of returning 185,000 acres of underwater grass beds. “To help restore the Chesapeake Bay, we must treat our shorelines differently,” the report said. “We need to protect or restore our shorelines’ natural riparian buffers and do a better job of managing shoreline development so that it does not exacerbate tidal erosion. We need to consider implementing environmentally sensitive or living shorelines to protect shorelines experiencing erosion of 2 feet or less per year.”
Environmental Concern, a nonprofit organization based in St. Michaels, MD, designs and installs living shorelines. Dr. Edgar Garbisch led Environmental Concern as one of the earliest proponents of the technique, which in the 1980s was known among resource professionals as “nonstructural shoreline control.” President Suzanne Slear said that damage from Hurricane Isabel helped to push the technique onto the public radar screen, along with a more marketable way to describe it.
“The term ‘living shorelines’ started to get wide publicity after Hurricane Isabel. Many residential shorelines suffered serious erosion, including those with structural erosion controls like bulkheads and rip rap. Shorelines protected with native vegetation—non-structural erosion control—suffered little or no damage,” Slear said.
Organizations and public agencies seized the opportunity to promote and explain living shorelines to curious home-owners.
“Now, people are becoming more informed about living shorelines, and the use of native plants in the landscape, which encourages native habitat and improves water quality,” Slear said.
The dual benefits of erosion control and habitat improvements are among the reasons that a regional partnership was formed to create more living shorelines, and another partnership was formed to help fund them.
David Burke, project manager for the Living Shorelines Stewardship Initiative, coordinates the efforts of a dozen partner organizations that want to make living shorelines the top management choice for waterfront property owners in Maryland and Virginia.
Launched in 2003, the initiative involves private grant makers, government agencies, nonprofit organizations, researchers and marine contractors working to document the effectiveness of living shorelines and promote the techniques to people who can implement them.
“Erosion is threatening thousands of acres of fringe marsh, which is a critical base for the food chain for higher-up predators and fish. When a loss that big is predicted Baywide, you need to do something about it,” Burke said.
Burke said the Bay ultimately needs a more holistic plan for living shorelines, rather than working through them on a site-by-site basis.
“One of the challenges to making this happen Baywide is familiarity and knowledge. That’s where outreach comes in. But we also need a supply of contractors familiar with this approach, and willing to do it,” Burke said.
Sometimes, seeing is believing. A 1,000-foot living shoreline restoration on the grounds of Environmental Concern has not only served as an outdoor classroom, but influenced additional projects on neighboring shorelines.
“We’re in a quiet location, but over the years the constant tidal influence and increased boating activity eroded the shoreline. Tree stumps, phragmites and other invasive plants lined the shore,” Slear said. “We involved neighborhood folks, volunteers from St. Michaels and high school students to help with the planting. It was a community event, offering the volunteers an opportunity to learn the steps in constructing a natural living shoreline firsthand.”
A stone sill was created offshore, parallel to the land and approximately 1 foot above low tide, to protect the outer edge of the restored wetland. The area behind it was backfilled with sand and graded to form a gentle slope from the waterline to the top of the existing bank.
Last November, volunteers planted cordgrass in the intertidal zone of the marsh. In higher areas, they planted saltmeadow hay, and on the upper bank they planted warm season grass with a strong root structure that can tolerate saltwater spray.
Several neighbors in the area are now planning living shorelines of their own, and another is proposed at an adjacent park.
“When they saw the finished product, they were amazed at how quickly the plants had matured. By summer, the shoreline looked like it had been there forever,” Slear said.
Environmental Concern is helping the interested landowners apply for funding support from the Natural Resource Conservation Service Wildlife Habitat Incentive Program.
Other grant makers, both public and private, have combined resources to encourage living shorelines in the Bay region, especially those with high demonstration value. Supported by the Chesapeake Bay Trust, the National Fish and Wildlife Foundation, the National Oceanic and Atmospheric Administration, and the Keith Campbell Foundation for the Environment, the new Living Shorelines Grant Program recently awarded $310,000 for eight projects in Maryland and Virginia.
Living shorelines techniques vary in response to site-specific characteristics, but they all emphasize erosion control methods that avoid hardening the shoreline and promote natural habitat. Still, there is some debate about how to define a living shoreline.
“Some would say there shouldn’t be any hard structure at all. But the ultimate goal is to create a fringe marsh, and sometimes well-placed stone is needed to get the grasses established. There’s a lot of middle ground,” Burke said.
“Living shorelines can have a structural component, but it’s just one component. It’s no longer the first line of defense—it’s there to protect the vegetation,” Opel said. “Isabel made it over serrated breakwaters, but it tripped over them on the way and dissipated the wave energy before it reached the shoreline.”
That’s key when miles of Maryland and Virginia shorelines are hardened each year, making them increasingly vulnerable to storm damage and removing valuable habitat for fish, crabs and waterfowl.
As Burke explained, “It’s a race with time to reach people, before we button up the Bay shoreline. Once that happens, it’s difficult to undo.”
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