Catastrophic coastal flooding is inevitable if we don’t act now
by Shelley Cameron-McCarron
Ask Dr. Jeff Ollerhead, a coastal geomorphologist at Mount Allison University, about potential coastal flooding risks facing the Isthmus of Chignecto—a narrow, 24-kilometre stretch of land, the sole land bridge joining New Brunswick and mainland Nova Scotia, and a key trade corridor for both road and rail. He doesn’t mince words.
“We’re living on borrowed time. In the Bay of Fundy, we’re absolutely running on borrowed time. If the right storm comes up the Bay, there are too many sections that won’t hold.
“That’s the situation we’re dealing with: lots and lots of dyke wouldn’t withstand the right kind of storm.”
The infrastructure, the dykes which hold back the Bay of Fundy waters, are in many places not high enough or wide enough or strong enough to withstand a major storm that occurs in a spring storm on a spring or moon tide, where the tides could be up to two metres higher than a neap tide, a time in the cycle when the tides are not as strong.
“People here will sometimes say there hasn’t been a storm bad enough in 100 years,” Ollerhead says. But he notes in the last decade there have been storms where the water didn’t go over the dyke—but it could have, if it happened on a spring tide.
“We don’t talk about if, but when. Eventually it will happen.”
And if a storm comes on a spring tide, serious flooding could follow.
“We need a strategic dyke management plan,” Ollerhead says. “It’s about protecting the infrastructure. The time is now to actually do something on this particular issue.”
“The sea-level rise, it’s to a point given the right storm, a 150-year storm type of event, it will produce a topping of the dyke and it will run over the dyke,” says Mike Johnson, EMO co-ordinator for Cumberland County, Nova Scotia.
“Once that happens, a number of significant issues come into play, depending on the storm.”
If the Tantramar marsh floods, one of the biggest issues will be the economic downfall resulting from the temporary shutdown of the Trans-Canada Highway and rail service, which run side by side for a significant portion, where it’s estimated $50 million in goods and services travel through every day.
Homes in border towns Amherst, NS and Sackville, NB and surrounding areas could also experience significant impact.
Johnson says on one hand it’s good nothing major has happened in the area for a long time, but by the same token it leads some to believe it won’t happen, so they don’t protect or prepare themselves properly.
“We’ve had those issues. They’re here at our doorstep. All it’s going to take is the right storm.”
In New Brunswick, where the province has been generating sea-level rise and flooding estimates for its coastal sections since 2012, figures show the projected sea-level rise in the Chignecto Isthmus zone will range from 0.88 metres to 1.53 metres in the worst-case scenario (melting from glaciers, ice caps and ice sheets), says a government spokesperson.
New Brunswick’s Department of Transportation and Infrastructure says government understands the importance of the Chignecto Isthmus, and the potential impact to this trade corridor from future climate change events is why the department is proactively working with counterparts in Nova Scotia and the federal government to complete a detailed engineering and feasibility study to determine how to best protect the Chignecto Isthmus trade corridor.
The federal and provincial governments have jointly promised $114 million in funding to strengthen and improve more than 60 kilometres of dikes in Nova Scotia to protect against coastal flooding, ostensibly exacerbated by climate change.
Natural process
Coastal erosion—the process in which land along the coastline is broken down and displaced due to naturally occurring processes, such as wave action, currents, tides, ice, or other impacts of storms—is not new, and indeed is a natural part of ocean geography.
“You wouldn’t have salt marshes and beaches if you didn’t have erosion. You actually jeopardize these features if we try to stop erosion. We risk losing these natural coastal environments,” Ollerhead says.
It becomes an issue when people choose to locate in areas where they are, or the natural environment is, at risk.
“Can you live on the shoreline? Can you live on a river? Sure you can. If you don’t appreciate how the natural system functions or changes, you can be putting yourself in harm’s way.”
Climate change causes the frequency and intensity of such natural events to amplify, increasing the degree of coastal erosion, which can have dramatic effects on infrastructure, often resulting in having to repair or relocate roads and buildings, says the Department of Environment and Local Government spokesperson. Increasing sea-levels can lead to increased erosion of the coastline, especially where the presence of sea ice is also being reduced by increasing water temperatures in our oceans.
Mike Johnson says sea-level rise and climate change are both issues along the Northumberland Strait and the Bay of Fundy. “Climate change is driving sea-level rise and sea-level rise is an issue for both coasts.”
It’s a complicated issue, particularly as not every place faces the same problems, Ollerhead says.
The issues of the Northumberland Strait versus the Bay of Fundy versus the Atlantic Ocean are in some cases the same, but in others, very different. What happens in Antigonish won’t be the same thing that happens in Halifax or Corner Brook. The land is doing different things, depending on where you are, so what works in one area may not in another.
“One way to simplify it is climate change is variable, sea-level rise is variable, erosion is natural, communities need to understand their own context.”
Ollerhead says the climate is the harder question to answer as you need longer records. Certainly there is lots of evidence that the climate is changing, he says. Sea level-rise, though, is unequivocal, he and will keep rising at an accelerated rate.
“People who say they don’t believe in climate change, that’s fine. If you say you don’t believe in sea-level rise, it makes no sense. The evidence is all around you. The evidence is immovable.”
PREPARING FOR CLIMATE CHANGE
In March 2019, then-environment minister Margaret Miller introduced legislation for a Nova Scotia Coastal Protection Act to help protect the province’s natural ecosystems and to set clear rules that ensures new construction is built in places safer from sea-level rise and coastal flooding. The bill had been through second reading and was headed to law amendment as of press time.
“People ask are we trying to protect people from the coast, or the coast from people? The answer is both. People want to live near the water and sometimes they make unsafe decisions. This act will go a long way to avoiding those types of problems in the future,” says John Somers of Nova Scotia Environment. Nova Scotia is a very coastal province with about 70 per cent of the population living within 20 km of the coast.
The act is all in the context of inevitable sea-level rise in the coming decades, he says.
Consensus is sea level in much of the province will be up one metre at the end of this century. The Intergovernmental Panel on Climate Change (IPCC) Report, a thorough assessment by 830 scientists from more than 80 countries, predicts that by 2100, global sea level will rise by about a metre.
“We want to make it so it is not only safe to build today, but it is safe in the longer term.”
Somers says the act is very future-focused, and an important part of climate change adaption. It’s a framework that will give the government the authority to delineate a coastal protection zone and the details will be in the regulation, he says.
Having passed with royal assent, it will take 12 to 18 months to develop those regulations, and Somers says the government will consult broadly.
He says it’s important to note the act doesn’t mean people can’t build near the shoreline. It’s intended so people don’t build where resulting structures will be at risk of storm surge damage, coastal flooding or coastal erosion, or where it could damage natural ecosystems like dunes or salt marshes. As well, there’ll be exemptions for certain industrial type applications such as fisheries, marine renewal energy, and agricultural marshland.
“It’s already a complicated environment,” he says, “The act is designed to avoid conflicts with other regulations.”
The Coastal Protection Act is an important step, says Nancy Anningson, coastal adaption senior co-ordinator with the Ecology Action Centre in Halifax, NS.
“Sea-level rise is taking what is already an issue in some places and really exacerbating it. It’s like adding an exclamation point at the end of the sentence.”
Sea-level rise and climate change are scary, complex stuff, she says, but the good news is if we know what we’re dealing with, there are things that can be done.
“There are a lot of things we can do to prepare and protect, like the Coastal Protection Act in Nova Scotia. We’re protecting ourselves better for the future.”
The EAC is working on a project focused around collecting sea-level rise research and evidence and presenting the information on a website to educate and plan for future impacts.
Erosion, she says, is an issue around Nova Scotia’s coast in different ways in different areas. Sandy soil erodes quickly, so these areas face bigger problems than rocky or clay soil. The type of coastal landform, wind and wave exposure, slope and sand are all factors in erosion.
Nova Scotia, she says, does have the advantage of having different conditions around the province, including wetlands, dunes, and rocky areas.
Flooding in North Rustico, PEI affected a number of nearby businesses.
Credit: UPEI Climate Research Lab
Not so in Prince Edward Island. Erin Taylor, with Communities, Land & Environment, says shoreline erosion is a particular issue because of PEI’s mostly-sandstone geology. As sandstone breaks down easily, it doesn’t take much force to change that.
“Because erosion has always been an issue on PEI, the province has had guidelines and rules in a piece of legislation called the Planning Act, which says new development has to be at least 60 feet back from the shore or 60 times the erosion rate,” she says.
While legislation dealing with erosion has been in place for years, Taylor says the province is now starting to deal with flood risk and is in the process of developing province-wide coastal flood risk maps.
To understand climate change, she says you need a long series of data because the coastline is so dynamic with both normal annual change and long-term change to consider. The department has been involved in a number of initiatives to collect this information.
Taylor says for the past five years they’ve partnered with the University of Prince Edward Island (UPEI) to measure the coastline annually at a number of established erosion monitor sites. Some parts of the province have seen bigger changes than others, in part due to wave dynamic and local geology.
Another partnership with UPEI uses drones to monitor coastal change in the shape of the dunes and beaches; while the department also compares aerial photography of the province taken every 10 years, to help determine coastal change.
Over the past number of years, they’ve been experimenting too with ways to protect coastal infrastructure. Following a major storm in the 2000s, they worked with a consultant to protect heavily damaged tourism assets. Not wanting to add armour stone, which isn’t native to PEI, they built a dune and planted marram grass.
In 2018, an inner tidal reef made of Island sandstone was installed by the Souris causeway and shoreline, an area often subjected to erosion and flooding. Ms. Taylor says they placed two piles of rock, strategically arranged adjacent to the beach as a way to dull the wave action but also to trap sand. They’ve been monitoring the site for the past year, and she says things appear to be positive. The long rectangle of rocks is also expected to provide aquatic species habitat.
In New Brunswick, a government spokesperson says since 2002, GNB has had the Coastal Areas Protection Plan for New Brunswick (CAPPNB), which provides guidance and recommendations about developing in coastal areas and along coastal features.
Some municipalities have used the document as a foundation for their own bylaws relating to coastal development. CAPPNB, as well as the 2002 New Brunswick Wetland Conservation Policy, say that existing coastal marshes are the remnants of a formerly, more widespread and abundant wetland type which has often experienced severe damage. Consequently, coastal marshes are categorized as Provincially Significant Wetlands and are awarded the highest degree of restriction in terms of permissible activities.
New Brunswick’s climate change projections indicate the province will experience increased temperatures, rainfall, and an increase in the frequency and intensity of storms. These projected conditions have the potential to negatively impact infrastructure, communities, and various sectors.
(Editor’s note: We are 100 per cent coastal, which means the ocean
will continue to steadily eat away at our shorelines as it has for
millennia—but is the process accelerating? We have previously
looked closely at Prince Edward Island’s vulnerability—but the
risk is widespread.
This time we take a look at the Isthmus of Chignecto, where
speculation that Nova Scotia might actually become an island is
no longer completely considered a joke.)
Intro Credit: Communications Nova Scotia
Intro caption: Queensland Beach near Hubbards, NS has seen local
roadways severely damaged, and in some cases, closed.