‘Living shorelines’ becoming more common in CT for erosion control

Good News Notes:

Visitors to East Shore Park in New Haven aren’t easily able to stroll along the beach there. It’s not closed; it’s being physically cut off from the rest of the park by erosion.

Getting to the beach requires getting down a steep slope, and there’s a good chance of slipping on the loose sand and dirt. Storms and high wave energy have eaten away at this thinning beach, and the few patches of vegetation are in the process of being flooded. Sloping rock walls called revetments built to stop this erosion have not done enough to stop it from happening.

These preventative measures have ended up isolating the beach from the park even more, said New Haven City engineer Giovanni Zinn.

The city is attempting a new solution to both protect and integrate the beach back into East Shore Park: a living shoreline. 

Living shorelines are erosion control projects that focus on safeguarding coastal habitats. The one being built at East Shore Park will consist of native plantings that stabilize the beach and mimic natural erosion control processes, as well as stone walls called sills placed just off shore that break the wave energy but don’t block off the shore entirely. 

“We really wanted to take a different attack, a more natural attack, and use a living shoreline as an opportunity to not only protect the park but also create a beautiful natural space to enhance the park,” Zinn said. New Haven is currently waiting for all of the required state and federal permits for the project, and Zinn estimates it will take six months to a year for full approval to start construction. In the meantime, more of the coastline is likely to be washed away by the encroaching waves. 

Living shorelines are becoming more common in Connecticut as beach erosion from storms and waves — and sea level rise — threatens coastlines. UConn’s Connecticut Institute for Resilience and Climate Adaptation (CIRCA) predicts sea level will rise by 1 foot 8 inches by 2050. That amount of sea level rise does not bode well for Connecticut beaches when combined with an increased number of severe storms hitting the state every year, as higher sea levels can worsen erosion and lead to more frequent flooding. It also means a high tide or storm surge will cause extensive damage. 

Connecticut communities like New Haven stand to lose a lot from increased flooding. The non-profit research and technology group First Street Foundation predicts New Haven will face a 51% increase in financial loss from climate change, and that the average expected loss per property from flooding will rise from $4,063 in 2021 to $5,226 in 2051. 

A 2017 study by the University of New Haven also found the economic cost of 1 meter of sea level rise in the city would be $1.3 billion, and $2.2 billion if it increased by 2 meters. With erosion increasing in cities such as New Haven and Bridgeport, this will make flooding even more common as beaches lose integrity. 

And much of the shoreline in New Haven, especially in the Long Wharf area, used to be part of the harbor itself. It is built on fill.

Kevin O’Brien, a supervising environmental analyst from DEEP, said Connecticut will soon have to deal with the threats of sea level rise and coastal erosion. 

“The impacts are there. We see it. It is happening. So the more that we can be thinking about how to be proactive about that and responsibly manage it and adjust to it, the better off we’re going to be. At some point, you’re going to wake up and [life is] going to be radically different for people,” O’Brien said.

Traditional erosion control methods won’t cut it

As towns and cities on the shoreline face this threat, finding an effective method of coastal protection becomes a priority. Right now, traditional erosion and flood control structures such as seawalls and revetments are common along Connecticut’s shoreline and are found in towns such as East Haven and Branford. However, these structures can physically block coastal habitats from the water, according to Dr. Juliana Barrett, an associate extension educator for Connecticut Sea Grant. 

“One of the big issues with a seawall is that you put up the seawall and you’re blocking the land-water interface,” Barrett said. 

Susan Jacobson, another supervising environmental analyst with DEEP, has a simple explanation for separating living shorelines from traditional erosion and flood control structures. 

“If a turtle isn’t able to get from the water to the resource behind it, it’s a flood and erosion control structure,” Jacobson said. With a living shoreline, the turtle would not be blocked off from the water, according to Jacobson. 

O’Brien, the DEEP environmental analyst, said traditional erosion and flood control methods can both harm beaches and coastal habitats. 

“[Erosion control structures] generally result in negative impacts to coastal resources. You know, if you put a groin in to stop erosion, you may get some [sand accumulation] growing on one side and then you’re starving the beach. On the other side, if you install riprap or seawalls, a lot of the animals and organisms that use that near shore area for breeding or feeding or roosting or whatever go away,” O’Brien said.

Seawalls can even cause beaches to retreat and become more eroded, O’Brien explained. When wave energy hits the wall, this energy travels downward and “scours out” the sand. Because of this, he thinks these structures are not a good long-term solution.

Another drawback of traditional flood control measures like seawalls is the cost to replace them, said Alex Krofta, an ecological restoration project manager from the New Haven nonprofit environmental action group Save the Sound.

“[Seawalls] often have a design life, and they don’t last forever. And when you do end up having to replace those, that I think is where the costs really add up,” Krofta said. 

Barrett, the educator from Connecticut Sea Grant, is confident people will grow used to the idea of a living shoreline when it comes to protecting the state’s coast once they understand how a living shoreline works. 

Living shorelines are much more beneficial for coastal habitats, Barrett argued. They don’t block off coastal habitats from the shoreline, and they focus on protecting areas such as marshes and wetlands. As opposed to traditional structures, living shorelines let water through.

“People don’t realize the long-term environmental damage that can come from having a seawall. We’re all very comfortable with the idea of a wall. And we’ve gotten used to seeing them,” Barrett said. “Living shorelines are new and different, and it’s like, well, what is this? How is this going to protect me or my property? But people love going to the shore. The really important thing is that living shorelines are helping to protect the environment as well as issues that people have with coastal erosion and to some degree flooding.”

Green and hybrid living shorelines

There are two main groups of living shorelines, Barrett explained. There are “green techniques” that use moldable biodegradable logs shaped to fit the shoreline and also make use of plants to both prevent erosion and create habitat. There are also “hybrid techniques” that use both these green techniques and off-shore rock sills or breakwaters that dampen the wave energy and allow a marsh to build up over time.

The living shoreline in development at East Shore Park in New Haven is an example of this hybrid technique. According to city engineer Zinn, rock sills will be placed offshore at the intertidal mark to break the wave energy. Plants will be added to fill tidal marshes which will also absorb this energy. In addition, the shoreline will be graded back into a more gradual slope that is more resilient to erosion. Tidal wetlands inside the park will also be expanded, creating more habitat. 

Other notable living shorelines in Connecticut not only protect coastal habitats, but also infrastructure. The Hepburn Dune living shoreline project in Old Saybrook was created because the beach and dune system were breached during a bad storm, Barrett said. The breach caused homeowners in the area to become concerned that their homes would be threatened by flooding if another breach occurred, which led to the development of the Hepburn Dune living shoreline. The project includes a process called beach nourishment that consists of replenishing the beach with sand, as well as rock sills that break wave energy.

Will living shorelines work?

Because living shorelines are not as familiar as other methods of flood control such as seawalls, there is a sense of uncertainty as to how well they will work in the long run as sea level rises. 

O’Brien noted that living shoreline projects are new to the state, so there isn’t much evidence to point to when predicting the long-term effects. 

“I think the biggest drawback right now is there’s really not a big long-term operational history here in Connecticut,” O’Brien said. “Hopefully, if we were to have the same conversation in five to 10 years, the ones that we’ve put in place to function have performed successfully. We’ve improved on things, and now there’s a greater familiarity and a greater confidence in the public.”

“To a certain extent, it’s an investment by the state of Connecticut to figure out how these things work. So it’s a pilot installation in a sense,” Zinn said about the East Shore Park project. 

This investment may be worth it. Krofta of Save the Sound said he is confident living shorelines will be better suited for modification than traditional erosion control methods as time goes on. 

“It’s not just building [the living shoreline] and wiping your hands and walking away,” Krofta said, “but building it and then setting up a pretty robust monitoring program and adjusting as time goes on as needed — to make sure not only that they are working well but also that we’re learning from the examples that we’re able to implement.”   

Zinn also thinks the project at East Shore Park will be changed over time.

“It will require some work and maintenance, and we’ll find out what the lessons are,” he said. 

There is some evidence that living shorelines can work in Connecticut. A living shoreline project in Stratford Point was built in 2014 — and later expanded — consisting of artificial reef balls that both break up the wave energy hitting the beach and provide habitat for clams, mussels and fish within their cracks and crevices. The artificial reef offered protection for the degraded tidal wetland behind it, and according to O’Brien, the Stratford Point wetland became much healthier after the reef was installed…..”

View the whole story here: http://ctmirror.org/2021/07/28/living-shorelines-connecticut-beach-erosion/

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