The race to rebuild living shorelines

Along the New England coast, recreated ‘nature-based systems’ such as salt marshes will boost resilience to the rising sea—when we figure out how to build them at scale.

The idea behind “living shorelines” engineering is straightforward: Natural defenses such as salt marshes and oyster reefs often can guard vulnerable stretches of coastline better than seawalls and other forms of gray infrastructure, and help to restore endangered coastal ecosystems at the same time.

Case in point: An eroding sandy bluff above Narragansett Bay in East Providence’s Rosa Larisa Park. Concrete walls weren’t stopping the bluff’s erosion, said Leah Feldman of the Rhode Island Coastal Resources Management Council at a December 9 meeting on nature-based adaptation in Boston. In contrast, two living shoreline measures, a salt marsh planted with Spartina cordgrass (above) and a bank stabilized with coir logs and beach grass, are performing well.

However, despite a sprinkling of early success stories like this one, “there’s hardly any practice of living shorelines in New England,” said Alison Bowden of the Nature Conservancy at the meeting, which was sponsored by the Environmental Business Council of New England and the Sustainable Solutions Lab at UMass Boston. “So why is that and what are we going to do about it?”

She pointed to two holdups specific to New England plus two barriers on the federal level.

One nagging problem is the common doubt that nature-based approaches can deal effectively with the rigors of our coastal environment—the short growing system, ice and high tide range. But believing that a salt marsh that has withstood every storm for thousands of years is less resilient than a wall “is kind of nuts,” Bowden remarked. “Does anybody think a seawall will have a 6,000-year design life?”

Another big hurdle is that each New England state ignores the national wetlands permitting process and sets its own rules. The resulting lack of design standards endlessly complicates regulatory reviews. (Bowden and many allies took on this challenge in a regional analysis that drew lessons from 15 projects.)

At the federal level, the Clean Water Act was written in the 1970s primarily to keep developers from fouling up bodies of water. That goal made a great deal of sense at the time, but the lawmakers didn’t imagine today’s needs to restore badly damaged ecosystems and to protect against the ever-more-obvious effects of climate change. “I’ve spent a good part of my 21 years at the Nature Conservancy working on figuring out how to get the regulatory environment to let us do things like dam removal and salt marsh restoration,” said Bowden.

Moreover, federal regulatory reviews focus on protecting what is there today rather than what may be there in a few decades. “We can’t really keep what we have over time,” Bowden emphasized. Instead, we need to think carefully about tradeoffs—like, when does it make sense to work toward an ecosystem that’s healthy but not the original ecosystem?

This question already looms for Belle Isle Marsh, Boston’s last salt marsh (above), which doesn’t have much room at all to migrate inland to accommodate rising sea levels.

Better planning for such environmental puzzles needs better data. And while coastal engineers can tap into many decades of information about seawalls and other gray infrastructure, relatively little is known about the performance over time of living shoreline engineering with our region’s salt marshes, oyster reefs, dunes, beaches or seagrass meadows.

Small pilot projects such as Rosa Larisa Park are starting to fill in the gaps, but truly scaling up will demand information we just don’t have. Gathering that knowledge is the mission of Boston’s Stone Living Lab, now conducting a wide range of experiments with various partners. Perhaps SLL’s most intriguing project is to try defending the eastern shore of Rainsford Island (above) with a combination of rocky reef and cobble berm.

The most spectacular living shorelines initiative on the U.S. Atlantic coast, New York’s $107 million Living Breakwaters project (below), also is producing a flood of data.

Scheduled to wrap up construction by 2024, this project on Staten Island, which was the epicenter of drownings in Superstorm Sandy, is designed not to keep the ocean entirely out but to reduce storm risk, enhance ecosystems and foster social resilience along the coast. The centerpiece is a half mile of near-shore breakwaters that not only will bring down storm waves but capture sediment and build the shoreline back, said Pippa Brashear of SCAPE, the lead designers.

The breakwaters aren’t oyster reefs but are carefully crafted to be similarly hospitable to marine life. “Like any good designer, you ask, What does my client need?” Brashear said. “In this case, we were asking how fish, crabs, lobsters and benthic invertebrates will use this.”

Across the country in San Francisco Bay, the Oro Loma Living Laboratory presents another innovative take on living shoreline studies. Built in 2018, this research platform examines “horizontal levees” that install a broad wedge of wetland between a levee and the bay (below, left to right).

“The idea behind the horizontal levee is that you can provide flood protection through a natural system, while also treating wastewater within that system,” said Heidi Nutters of the San Francisco Estuary Partnership. “The freshwater input can also increase the plant growth and improve success of restoration just by having water at the site. And the brackish marshes can build organic soils and help keep pace with sea level rise.”

The Oro Loma lab has demonstrated that microbial processes at work below ground in the wetland wedge can remove contaminants such as nitrogen from treated wastewater. Investigators now are testing the levee on highly saline water trucked in from a desalination plant.

Down on the Gulf Coast, Bowden and colleagues analyzed Google Earth images to make a striking finding about Hurricane Michael, which hit the Florida panhandle in 2018 as the first category 5 hurricane to make landfall in the U.S. in almost 30 years. “Pretty much no gray infrastructure survived,” she said, but only 2% of the salt marshes in the study area were damaged.

“That’s a pretty impressive performance on the part of nature,” Bowden remarked. “Natural processes know how to stand up to nature, and we need to learn from them… to help us as the climate changes.”

Storm season

What we’re learning about hurricanes. And how societies handle them.

I’ve lived through impressive tropical storms, twice on sailboats safe in harbor, but I can’t really imagine a hurricane with 150 mph winds like Ida. That’s the business of coastal scientists, engineers and other experts. Here’s what they’re telling me:

  • It might not always seem this way, but in the past few years the National Hurricane Center has notably upped its game for predicting storm tracks.
  • Structural engineers can now simulate hurricane risks for each individual building in a region, by combining advanced storm simulations with machine learning tricks to predict each building’s shape and strength. Coastal Louisiana, appropriately enough, is one testbed for this NSF-funded open collaboration.
  • The lamentable history of New Orleans before and after Hurricane Katrina is beautifully described in Andy Horowitz’s Katrina. Once again Hurricane Ida is highlighting society’s lack of interest in guarding the vulnerable, while maintaining systemic foulups like police focused on protecting property rather than people.
  • The rebuilt New Orleans levee system “is less ambitious than the one Louisianans lobbied for after Katrina, and the protection it offers grows weaker every day, as the wetlands that buffer the city from the Gulf of Mexico get wetter,” as Horowitz wrote in the New York Times. “But it kept the Gulf of Mexico out of the city, which was its job.”
  • That was a straightforward goal for the Army Corps of Engineer’s $15-billion New Orleans levee project. Achievable goals may be far less clear for megaprojects under consideration for other U.S. cities. Case in point, Miami just turned thumbs down on a Corps plan built on a massive seawall.
  • Miami is among the urban areas hoping to adopt “nature-based systems” (oyster reefs, salt marshes, sea grass meadows, mangroves… ) as part of their resiliency efforts. NBS is a big theme in the Texas coastal spine proposal, centered not just on enormous sea gates but on miles of sand dunes. As with traditional gray engineering, NBS measures have strengths and weaknesses; salt marshes retain no magic if they’re buried under a surge of seawater.
  • There remains the little problem of paying for coastal adaptation measures–ideally, before disasters hit. Boston, which is doing a commendable job of planning for climate change, is among the cities puzzling to find the vastly greater sums needed for actual construction.
  • Traditional benefit/cost analyses for such projects that consider only financial factors “might lead a government to protect only the parts of a city that contain high-value properties while dismissing parts of a community where less advantaged people live,” notes a National Academies report on localized climate action.
  • There’s much talk about “managed retreat” from endangered coastal sites but so far this radical step is taken only when there is no choice at all. “There are reasons people live where they live,” as one prominent engineer pointed out to me.
  • Hurricanes can rip away the accoutrements of civilization over surprisingly huge areas–for instance, Ida killed more people in the Big Apple than the Big Easy. But with the huge exception of rainfall, the worst structural damage is usually highly localized. Properly designed and constructed buildings often survive hurricanes surprisingly well, and the big problem for their occupants becomes waiting for restored power, water, roads and other lifelines.

See also What survives the storm

Rethinking resilience on Staten Island

Living Breakwaters will bring many coastal benefits, but direct flood protection is not among them.

When Superstorm Sandy hit Staten Island at the mouth of New York Harbor, the storm surge rose to 16 feet and 24 people died. Eight years later, the island is inching ahead on raising new seawalls and rebuilding dunes and buying out properties in the zones that can’t be protected.

And launching Living Breakwaters, a pioneering “nature-based” project off the town of Tottenville in the southwestern corner of Staten Island, which is finally out for construction bids.

Living Breakwaters will install a set of eight meticulously designed, partly submerged structures aimed to reduce shoreline erosion and storm waves, help to restock local finfish and shellfish populations, and offer opportunities for community learning about marine ecosystems and social resilience.

The $60 million project originated in the Rebuild by Design competition held by the U.S. Department of Housing and Urban Development after Sandy, said project leader Kate Orff, speaking at a University of Maryland Center for Environmental Science webinar on November 5.

“What’s truly innovative about this project is it aims to be combinatory,” said Orff, founding principal of SCAPE, a landscape architecture and urban design studio in New York. “It combines risk reduction of a physical breakwater with fostering an active shoreline culture, rebuilding the shoreline, and rebuilding the three-dimensional ecological substrate through active oyster restoration.”

What Living Breakwaters won’t do is keep out floodwater.

Instead, they will work in tandem with a dune restoration project, one of whose goals is flood reduction.

“Just stopping flooding is only one of maybe 10 different concepts that we have to think about when we think about purpose,” Orff said. “If one were to build a four-foot linear seawall in this area, with any intense rain event the entire town of Tottenville would get flooded out.”

The breakwaters are configured to bring down the crests of waves coming from the east and southeast, the most common direction in storms. The structures also will minimize shoreline erosion, which is primarily driven by day-to-day waves, and help marine ecosystems recover more quickly after storms.

The design goal is to handle storms with up to 30-inch sea-level rise. “One of the nice things about breakwaters is they don’t stop functioning with sea-level rise,” commented Joseph Marrone, associate vice president and area lead for urban and coastal resiliency at the international engineering firm Arcadis. “They’ll still provide wave reduction and erosion reduction… along with the ecological benefits.”

Built with a mix of hard stone and “bio-enhancing” concrete, the breakwaters will incorporate precast tide pools and other components tailored to provide niche habitats for many marine species. Additionally, “we worked with the Billion Oyster Project and educators on shore to advance the idea of oyster gardening and rebuilding the historic reefs that were once part of this ecosystem,” Orff said.

She sees bringing back such ecosystems as an obligation in resilience projects.

Moreover, it’s critical to test these natural and nature-based measures at scale. “A 20-by-20-foot bed of wetlands won’t have a lot of impact relative to risk reduction, but larger contiguous systems absolutely will,” she said.

“As we are looking more towards natural nature-based features, because we are looking now simultaneously at the climate crisis, sea-level rise, more rainfall, et cetera, we’re also looking at a crisis of biodiversity,” Orff emphasized. “We need to begin to think about all of these things at the same time.”

And to plan more proactively, “because otherwise we’ll get constantly caught in this disaster response framework,” she said.

Resilience roadmaps should stop focusing solely on protecting today’s built shorelines, Orff suggested. Instead, they can reflect how those dynamic coastal environments might benefit from layered solutions “that can keep people safer and can also keep our shorelines living and alive and suitable for marine life,” she said. Among the options, nature-based measures often may be much better suited for the wild complexity of future environments and events.

Orff also calls for a common blue-sky vision in which the almost endless groups of coastal stakeholders all march in the same direction. “When we’re just working at this tiny scale and fighting the small battles, it feels like we’ll never add up to enough to really meet the climate crisis and ecological crisis that we’re facing,” she said.

Great August 2021 snapshot in the New Yorker: Manufacturing Nature.

Images courtesy SCAPE and Arcadis.

Surge protectors

Will the Boston Harbor ocean barrier rise again?

Built on four centuries of filled land, Boston is wildly vulnerable to the next major hurricanes or winter northeasters. These risks only accelerate as storms get worse and sea levels rise. To their credit, the city and state understood this exposure years ago and have been steadily working away on climate resilience initiatives. One project was to consider a grand Boston Harbor barrier that would close off much or all of the harbor against big ocean storms. A study led by the University of Massachusetts found, however, that such a barrier would be thoroughly impractical.

But maybe not. William Golden, famous here for kicking off the legal struggles that triggered the harbor cleanup a few decades ago, today launched an open meeting of a Boston Harbor storm surge working group. The group’s premise is straightforward: the best defense against the sea is a layered defense that combines a re-thought harbor barrier (to fend off the storms) and relatively modest local measures such as berms (to handle sea level rise).

Among points by Golden and his allies:

  1. There are many alternative barrier routes and designs, some sketched out above by Duncan Mellor of Tighe & Bond. These might mostly follow shallow water, use dual gates for the shipping channels rather than the never-built-anywhere single gate structure examined by UMass researchers, and be considerably less massive. That might make them dramatically less expensive than the $7-12 billion pricetag UMass experts suggested.
  2. Depending on your assumptions about how long construction takes and what you pay for money (discount rates), costs again might drop significantly. And unlike smaller projects, federal funding just might be available.
  3. A barrier that guards the entire harbor, not just Boston, could provide benefits that no one has counted yet. Most dramatically, the savings in regional flood insurance payments might be many times the investment.
  4. The default alternative of building high local berms/seawalls everywhere brings up seriously worrying questions. For one, what about the places that can’t afford them? For another, how will all these patchwork walls connect? And do we really know how to efficiently build a watertight 20-foot seawall all along, say, the North End waterfront, with its crazy web of buried infrastructure and weak geological underpinnings?

Our safeguards against the sea will have domino effects far beyond Boston. “This is going to affect the economy of the whole region,” Golden said. “It’s an existential threat.”

Pre-filled Boston, courtesy Leventhal Map & Education Center, Boston Public Library

Watching the river flow

The Thames Barrier is still prepped for decades defending London against high water.

On Tuesday, the warmest winter day ever recorded in Britain, there was not a cloud in the sky over the Thames Barrier. A tug calmly pulled its barge through one of the channels in the Barrier, which shuts off the Thames when the incoming tide will rise over sixteen feet. This offbeat superdam doesn’t look like anything else: a necklace of giant steampunk silver mussel shells stretched a third of a mile across the river. London began seriously contemplating means of protection after a major dousing in the great North Sea storm of 1953. The Barrier went into operation three decades later. It has decades of usefulness ahead; although climate change was not considered in its design, sea levels along the southern English coast aren’t inching up from geologic causes as fast as originally expected. The Barrier has been shut about 200 times, 50 of them in the 2013/2014 season, when the culprit was not super surges from the ocean but super rain surges that incoming tides would have pumped up further. “It is designed to be bomb-proof and failure-proof,” the Londonist once noted. “When a 3,000-tonne dredger hit the Barrier in 1997, the ship sank. The Barrier lost a ladder.” One of these decades, the enormous wall may be supplemented by a much more enormous dike downstream. In the meantime, “the structure is fundamental to the lives of millions of Londoners,” the London Review of Books commented, “which may be the reason very few of them want to look at it.”

Canaries in a coal-mined world

Environmental writers tell great stories about life across our fast-changing globe.

We’re seeing a remarkable series of stories about climate change and other manmade or partly manmade threats—some even complete with hints of solutions. Here’s a fairly random baker’s dozen from this striking crop (hmm, only two of these pieces come from for-profit publications).