Special Report: How Engineers Are Preparing for Sea-Level Rise
From Seattle to Cape Cod, see what's being done at 18 different locations
Piloting his crab boat during a storm off Tangier Island, Va., Mayor James Eskridge sweeps his hand over the water and says, “I remember when all of this area was land.”
Below the water are the homes, stores and graves of the Tangier Island communities that have been swallowed by the sea. Since 1850, the island has lost more than 66% of its land mass. Today, the 1.2-sq-mile island continues to erode by as much as 25 ft per year.
“There are other communities around here that have disappeared,” he says. “We’ve seen what can happen to us if we don’t get the help we need.”
Eskridge says his island is eroding but thinks sea-level rise has little to do with it. Scientists, however, say erosion, saltwater intrusion, storm surges and king tides—an exceptionally high but predictable tide that does not result from a storm event but from an alignment of the moon, the earth and the sun—experienced in Tangier and elsewhere are being made worse by the rising sea level, and the problems will accelerate in the near future. The National Oceanic and Atmospheric Administration says nuisance flooding has increased in the U.S. between 300% to 900% from 50 years ago.
In this special report, Engineering News-Record’s team of editors and reporters look at how Tangier and other coastal communities around the country are tackling problems, including erosion, subsidence and sea-level rise. Our reporting has found that many cities are still trying to get a handle on the complex, interrelated problems. But others, such as Miami Beach, have started aggressive, multimillion-dollar programs to raise roads and improve drainage.
We also found that engineers are rethinking their practice, coming up with innovative, adaptive designs that will prevent overbuilding in the short term until future forecasts—which now say the sea level could rise between 1 ft to 8.2 ft by 2100—become more precise.
- Cape Cod's 'Big Little' Projects Will Combat Sea Level Rise
- The Anti-Seawall Seawall Fights Climate Change in Charlestown
- Community's Input Helps NYC's 'Big U' Project Take Shape
- Atlantic City Fights Storm Surge With 1,740 ft of New Seawall
- Erosion Trumps Sea-Level Rise on a Small Settlement in the Chesapeake Bay
- Hampton Roads Region Looks for a Way To Live With the Water
- After Battle With Erosion on Hatteras Island, Critical Road Rerouted Over Causeway
- Seeking New Solutions to Charleston's Age-Old Flooding Problem
- Short-Term Fixes Fight Erosive Forces Along N.C. Coastline
- Public Outcry Prompts Miami Beach's Action on Sea-Level Rise
- Discovery of Engineering Failure Leads Miami Beach to Flooding Fix
- Sediment Diversions Drive Strategy to Keep Louisiana Above Water
- Native American Band Abandons Eroding Home
- Vital Highway Gradually Rises Above Potential Storm Surge
- Delayed Action Raises Houston-Galveston Area's Storm Surge Risks
- Airports Assess The Risks to Runways of Rising Seas
- Digging down To Avoid Sea-Level Rise in Sacramento-San Joaquin River Delta
- Seattle Rebuilds Seawalls With an Eye Toward the Future
“You are seeing water in places you have never seen it before,” says G. Wayne Clough, a civil engineer, president emeritus of the Georgia Institute of Technology and former secretary of the Smithsonian Institution who often speaks on climate change. “This is the time for people to sit down and think rationally about what we are going to do.”
Spurred in large part by the disasters of Superstorm Sandy and Hurricanes Katrina and Matthew and the tidal flooding that affects some communities as often as twice a month, many cities and communities are trying to get their arms around the problem of sea-level rise and come up with solutions to accompanying problems like saltwater intrusion and stormwater runoff.
“We’re not quite there, but we’re getting there,” says Edgar Westerhof, national director of flood risk and resiliency for Arcadis North America. He notes that collaboration “always seems to follow a disaster.”
Following Superstorm Sandy, New York City’s “Rebuild by Design” contest spurred new resiliency measures. Hampton Roads and South Florida have regional groups that are looking at mitigation options to persistent flooding problems.
“Understanding the problem is really the most important piece,” says Josh Sawislak, global director of resiliency for AECOM.
Places like Annapolis that experience frequent tidal flooding “have gotten religion” and are formulating new approaches, says Lewis “Ed” Link, a professor of civil and environmental engineering at the University of Maryland who focuses on water-resource management and natural-disaster mitigation.
“Unless you wrap your arms around the risk situation, you can’t understand where your risk is coming from,” says Link. By understanding the problem, “you can become more resilient for things you can’t quantify, and you are more able to deal with surprise.”
Understanding the risk of sea-level rise requires communities and businesses to imagine what a global sea-level rise of 8 ft might look like for them.
Since 1901, global sea levels have risen about 7.4 in.—at an average rate that doubled in the 1990s—largely as the ocean has warmed and expanded and glaciers and ice sheets have melted. But the relative rate of sea-level rise has varied wildly by region. The East Coast and Gulf Coast are experiencing rates of sea-level rise up to four times the global average because of subsidence and ocean currents, while parts of the West Coast actually have seen relative sea-level rise decrease due to shifts in the tectonic plates.
Given the differing regional topographies and levels of relative sea rise, each community’s risks and solutions will be different. A seawall, for instance, would do no good in Miami Beach, where the water comes up through its limestone bedrock.
“How do you translate knowledge into action—it’s an ever-more relevant field. There is a need for interaction of people doing the basic research and people trying to translate that into big, concrete solutions,” says Bob Kopp, a climate policy scholar at Rutgers University and one of the world’s leading experts on the topic. Rutgers, he says, has started a new climate-resiliency program for engineers and scientists to help engineers and others make science-informed decisions.
Once a community knows its risk, it can plan to adapt. The adaptations usually fall into one of three buckets: defend, accommodate or retreat.
While some localities strongly support a defense based on seawalls and barriers, there are financial and engineering limitations to doing so along the entire coast of the U.S., says Erika Spanger-Siegfried, a senior analyst at the Union of Concerned Scientists (UCS). “How many localities can a state afford to defend? How many states can the federal government step in and defend?” she asks.
In places like New Orleans and Philadelphia, planners are working to accommodate extra stormwater and flooding with green infrastructure that can absorb and store large volumes of water.
Retreating from the coast is the last option, but Orrin Pilkey, a Duke University professor emeritus of earth and ocean sciences, says this withdrawal is inevitable in places such as North and South Carolina.
“We can do it in a planned fashion, which won’t be easy,” Pilkey says of the retreat option. “Or we can do it in a catastrophic way, which will be harder and more expensive.”
But retreat is not an option for many communities, such as Miami Beach. “They call me Gen. Patton—this is my line,” says Bruce Mowry, city engineer for Miami Beach. “When somebody says, ‘How much are you willing to fall back?’ I say, ‘Not one inch.’ We are defending this city at the shoreline. Miami Beach is only one mile wide. If we drop back a mile, we don’t have a city.”
Some areas, though, haven’t even begun to get a handle on the problem, let alone the solutions. North Carolina, Florida and other states have discouraged talk of sea-level rise and climate change. On the other hand, Darcy Immerman, senior vice president of resilient critical infrastructure at AECOM, says, “There’s been a slow kind of perception change. It’s still changing. Not everybody has woken up to the realization.” She adds, “Some people are focused on ‘This is the way we’ve always done it.’ I don’t know that we’ve hit the tipping point, but it’s coming.”
As communities move from identifying to addressing the problems associated with sea-level rise, they increasingly are looking at holistic solutions that comprise natural systems, hard infrastructure and policy.
At AECOM, this “menu of resiliency” includes civil engineering, landscape architecture and landscape design, as well as neighborhood-by-neighborhood outreach. AECOM’s Sawislak asks, “How do we build with nature, understanding that we can’t always say, ‘This is always going to flood, so we are just going to abandon it?’ ”
After Superstorm Sandy, the U.S. Army Corps of Engineers spent two years looking at just such a systems approach to protect the North Atlantic coast. The study, released in January 2015, extols the benefits of natural systems, including living shorelines, beach restorations, wetlands and reefs.
“Given current and projected sea-level and climate-change trends, some of our built environment will become unsustainable for the human systems presently located there. Coastal communities face tough choices as they adapt local land-use patterns while striving to preserve community values and economic vitality,” according to the study.
The study helped set the stage for the Corps to use a systems approach in protecting the coast, but the Corps does not yet have a policy for using natural systems, nor a good way to quantify the benefits.
This systems approach is a move away from a traditional engineering solution that, in the past, would have called for a wall or a gate to keep the water out.
“Today, we don’t have enough money to think we are going to spend $15 billion on every city,” says GIT’s Clough. And as efforts like New York’s Rebuild by Design discovered, people don’t want a big seawall blocking their view of the water.
Another strike against seawalls and barriers is the uncertainty of sea-level rise.
Because the dynamics of ice-sheet melt are still largely unknown, there’s not a high confidence in how much sea-level rise will increase beyond 2050. “There are possibly processes involved that we have the barest sense of today,” Kopp says.
So, rather than overbuild now, engineers are designing and building near- and midterm solutions. “How much do I have to do? I don’t want to build the Great Wall of China if we’re never going to need it,” Link says.
Adaptive design is an emerging engineering practice that addresses the uncertainty of climate change and sea-level rise. This design technique allows infrastructure to be built now, with the understanding that the underlying design assumptions might change. “In the past, we might have said to design to 60 years,” says Bryan Harvey, vice president and global operations director at CH2M. “Now we say design to 10 years, then a more sustainable solution” might present itself. Such a design incorporates more flexibility, response and fluidity.
Adaptive design allows engineers to sequentially work from what is known. “This approach is more affordable, and we learn as we’re doing,” Link says. “It’s turning a long-term problem into a series of short-term problems. We’re good at short-term problems.”
An American Society of Civil Engineers committee is currently crafting standards for adaptive design. “We need to change our design practices through design guides, ideally changing the standards” to account for sea-level rise and other climate-change uncertainties, says Bilal M. Ayyub, professor and director at the University of Maryland’s Center for Technology. He is chair of the committee working on a manual of practice for climate-resilient infrastructure (the manual is expected to be complete next year). The committee’s work has focused on sea-level rise, energy use, flooding, wind storms, and storm intensity, among other issues related to climate change.
For example, an “adaptive” philosophy would encourage a seawall’s life span to be engineered to the best estimates, but with a stronger foundation, Ayyub says. If it turns out those estimates are incorrect, the structure could be elevated without having to demolish and rebuild it. Already, that philosophy is being implemented in Seattle and New York City seawalls.
Ayyub says the new standards are being driven by clients who want design to account for the uncertainty. That expectation shifts the burden to engineers, who need guidance on how to implement adaptive design.
Adaptive design could also mean designing a structure to accommodate the water. “Hopefully, we are building things that can be adaptable,” says Clough. “It might be that we say that it’s OK to let this area flood—we have ways to deal with this. It’s not going to be a simple one-size-fits-all.”
GE, for example, is building its new Boston waterfront headquarters 20 ft above sea level. But in case that’s not high enough, the company is putting all mechanical and safety systems on the roof. “Our corporations aren’t just building things for one administration. They are building for the future,” says Clough.
Technological advances are helping engineers design for an uncertain future. Using a 3D camera and augmented reality, Arcadis was able to show one client what sea-level rise would look like for its waterfront building. In New York City, the firm used a supercomputer to analyze federal data and created 800 different storm and sea-level rise scenarios. “These tools can be really amazing,” says Westerhof.
Other tools, including drones and sensors, allow for the real-time monitoring of the impact of erosion and sea-level rise on structures. “With a better understanding of science, we can be much more reactive and preemptive,” says Harvey of CH2M. “You can capture these defenses before they fail, or use science and technology to prolong the life of that asset.”
Sawislak of AECOM says technology is being used more and more for infrastructure solutions to coastal problems, through geotextiles and biomimicry, for example. “It’s exploding,” he says of technology in the field. “You are adding huge amounts of technology to old-school conversation.”
No matter what solutions are presented, money is a huge limiting factor. “There’s lots of studying being done, but [communities] don’t have money to do anything,” says Link. In some cases, cities are waiting for the next bad storm to induce action on the part of the federal government, Immerman of AECOM points out.
But in today’s political climate, it appears that “Congress has backed off the level of generosity” seen after Hurricane Katrina, Link says.
Cities waiting for federal government to help will be left behind, says Greg Steele, chief of the water-resource division for the Army Corps of Engineers’ Norfolk District. “Communities that will have the greatest success are those that are working separate from federal [oversight], with zoning and building ordinances,” and seeking other funding sources, he says. The Corps can take on only a limited number of projects a year—and competition is fierce, Steele notes.
Future federal funding for coastal problems, which in the past has come from HUD and FEMA, is uncertain under the current administration. President Trump’s proposed budget would eliminate some climate-resilience programs that are helping coastal communities.
“The proposed budget was definitely going in the wrong direction,” UCS analyst Spanger-Siegfried believes.
Engineering can provide some funding solutions. In the Netherlands, for example, multipurpose levees incorporate water parks and parking garages. “It is high-end, but those features pay for these levees,” says Westerhof. “It’s a very strong business case.”
One of the few things that experts say is certain about sea-level rise is that it can be slowed if the amount of carbon dioxide in the atmosphere is reduced. “It’s a race. Give yourself as much time as you can,” Clough says. “The faster you put carbon” in the air, the more quickly the sea level will rise, he adds.
Kopp agrees, saying that slowing the rate of global warming “can significantly lower the probability of the most extreme outcomes.”
Another certainty is that engineers can play a crucial role by providing an understanding of the science the risks of—and the potential solutions to—sea-level rise. “We know that there are going to be really creative approaches that will come out of the engineering community,” Spanger-Siegfried says. “We are really looking forward to seeing those and hoping they are science-based with an eye toward equity … and none too soon.” ♦ With Scott Judy, Bruce Buckley and Jim Parsons