Climate change in Tantramar means four things:
1 Dyke Breaches and Flooding
2 Transportation Challenges
3 Economic Damage
4 Opportunities and Challenges for Agriculture
5 Health Issues
Dyke Breaches and Flooding
Tantramar is a unique area, home to the world’s largest tides, vast expanses of open marshland, and a network of dykes that span 33 km. It was Acadian settlers who arrived in the region in the 1670s and soon after began to dyke and drain the marshes, seeing the agricultural potential in their fertile soils. The Acadians built aboiteaus, a valve or flap, in the dykes to allow water to drain from the fields at low tide but prevent saltwater from entering at high tide. They were also used to drain the land after high tides and storms had forced the seas to overtop the dykes. Historically the dykes were built and managed to protect agricultural use of the marshes only.
Today the New Brunswick Department of Agriculture, Aquaculture and Fisheries continues to manage the dykes. It is important to realize that while part of the Town of Sackville is located on dyked lands and the town is partially protected by the dykes, the defence of Sackville against floods is not what the dykes are currently being managed for.
The current average height of the dykes around Sackville is 8.6 metres. The diagram belows shows the range of dyke elevations.
Below we can see how high each section of dyke was in 2012. The orange and red sections are lowest (and could easily be overtopped by storm surges), while the green shades are tallest. The longest stretch of lower dykes is also the CN rail line, running beside the Trans-Canada Highway approaching Aulac. There are also sections of lower dykes around the town of Sackville.
The dykes were built to protect agricultural lands, which can withstand periodic flooding. So the dykes can limit impacts from increases in sea level, but they are not high enough to protect the region from mildly severe storms, such as those that have a 10% chance of occurring in any one year (or a 1:10 year storm). The current scenarios estimate that a 1:10 year storm would see sea levels of 8.9 m (see maps below). Because the average height of the dykes is 8.6 m, a storm of this strength could overtop 89% of the dykes and flood roughly 20% of the town of Sackville (population 5,500). This extent of flooding translates into 156 buildings and 1,049 properties being affected. Major and secondary highways could be flooded as well as the town’s sewage lagoon, which shares its seaward wall with part of the dyke system. Agricultural lands will be flooded and some parts of Sackville with higher elevations may become islands, surrounded by flood water.
Many different climate change scenarios are being studied. A current 1:100 year storm that impacts Sackville could see a 9.8 m flood and extensive damage (see the map below). Both of the current 1:10 and 1:100 year storm events could happen anytime.
If or when sea levels reach 12 m due to storm surges and severe weather events, Nova Scotia could become an island (see map below). The existing highway routes are mapped below along with a hypothetical connector route along the highest terrain (white line).
If a 1:10 year storm occurred in the near future and dykes around Sackville are overtopped, there could be as much as 1.4 m of water at the corner of Lorne and Bridge Streets in downtown Sackville. Fast-forward to the end of the century, when there will be much higher sea levels and the same storm could overtop the dykes and fill the corner with 2.4 m of water (similar to levels seen during the Saxby Gale). If adaptation measures are not taken, future residents of Sackville will need scuba gear to get around down town!
Did you know?
When the dykes were originally built, their creation meant the loss of 85% (or 365 km2) of pre-colonial area salt marsh around the Bay of Fundy.
Removing certain portions of dyke (where they are not protecting infrastructure, buildings or active agriculture) and allowing the land to return to salt marsh is one climate change adaptation option that local groups such as Mount Allison University have been studying for many years.
Salt marshes have a natural ability to shift with rising sea levels, absorb and disperse intense wave energy, decrease erosion, and create a natural buffer area between sea and land.
They are also effective carbon sinks, taking in excess carbon dioxide.
Source: Marlin et al., 2007
Information about the dykes and flooding were taken from these studies:
Coastal Dykelands in the Tantramar Area:
Impacts of Climate Change on Dyke Erosion and Flood Risk
By David Lieske and James Bornemann, James (2011, 2012) http://atlanticadaptation.ca/node/283
Tantramar Dyke Risk Project:
The Use of Visualizations to Inspire Action
By Lori Ann Roness and David Lieske (2012)
An Evaluation of Flood Risk to Infrastructure
Across the Chignecto Isthmus
By Tim Webster, Malinee Kongwongtha and Nathan Crowell (Revised Dec 2012) http://atlanticadaptation.ca/
Sackville is certainly not the only community in the Tantramar Region at risk of climate change-induced flooding. Port Elgin, a village of just over 400 people, experienced two damaging flood events in 2010 as the photos here show. On January 2, 2010 the village experienced flooding from a nor’easter. The storm, measured as a 1:25 year event, moved cottages off their foundations and lead to a state of emergency being called. $900,000 worth of damages were estimated. Later that same year another nor’easter battered the small community and a storm surge caused coastal flooding.
The map below shows the extent of flooding for a sea level rise scenario in Port Elgin. A current 1:10 year storm event could affect 17 buildings and 109 parcels of land. Toward the end of the century, when higher sea levels are considered, the same storm event could flood 68 buildings and 198 parcels.
Memramcook, with a population just over 4600 residents, is also vulnerable to flooding due to sea level rise, storm surges, dyke breaches, and also because of damaged culverts. For example, the map below shows the potential extent of coastal flooding for current (in blue) and future (in purple for the year 2100) 100 year flood events. The red lines show the current location of dykes.
A number of culverts in Memramcook are damaged, blocked or partially blocked with rocks, debris, leaves, sediment, etc. as shown below.
The map below shows areas of potential flooding that could result from clogged culverts and closed aboiteaus. Areas with the darkest shades of orange represent the areas that could experience the deepest flooding. The lighter yellow shades are shallower areas of flooding.
Dorchester has experienced flooding in the past, such as with the Saxby Gale (below is an account of the aftermath of the gale). However, studies concerning storm surges, sea level rise and wet area mapping have yet to be completed for the village of 1,167 residents.
Accounts of the Saxby Gale, 1869 in Dorchester
At Dorchester the rise of the waters was eight feet, and they carried away all the fences, bridges, barns, hay, cattle, horses, sheep, and a large amount of dyking. The schooners Ida May and Independence, lashed to a wharf, were all carried a short distance above Smith & McKelvie’s quarry on the upland, where they still remain. A considerable amount of property was lost in the station. A new piano of Mr. Trites’ was nearly destroyed, and his family were much alarmed. An engine-cleaner at his work in the engine house was surprised by the waters, but climbed up on the rafters and remained there until next day.
Source: “The storm” From The Borderer. Sackville, N.B., October 14, 1869
The New Brunswick/Nova Scotia Transport Corridor is a part of the Atlantic Canada Gateway and Trade Corridor – a system of major ports, international airports, key border crossings, and road and rail connections between Atlantic Canada and North America’s major markets. A variety of commodities pass through the corridor such as gasoline and fuel, petroleum, wood pulp, machinery, automobiles, and various food products. The largest users of transportation in the area are manufacturing, forestry and logging, wholesale and retail trade.
For trade to be efficient it depends on accessible and reliable rail and road networks. In fact, the CN rail line moves 97% of all international traffic through the corridor, and right past Memramcook, Dorchester and Sackville. The Trans-Canada Highway is the second most important transportation route in the region.
Climate change is predicted to affect the New Brunswick/Nova Scotia Transport Corridor in five important economic ways:
1 Damage to roads, highways, etc.
2 Disruption in transportation operations
3 Travel time loss (due to traffic interruptions/delays caused by storms, floods, etc.)
4 Increase in costs of transportation accidents and derailments (property damage, hospital care, traffic delay, emergency response and out-of-pocket expenses by the victims)
5 Loss of labour income and profits in related sectors (the transportation network is a central part of the regional economy and climate change will affect all its users directly and indirectly including agriculture, forestry and the general public)
Climate change impacts (flooding, extreme weather events, general worsening of weather conditions) are estimated to cause a disruption in transportation operations to a total value of just over $1.07 million per year in 2013 dollars.
The overall annual economic loss from the cumulative effects of climate change impacts on the New Brunswick/Nova Scotia Transportation Corridor is estimated to be over $11.8 million per year (in 2013 dollars).
It may be necessary to invest in mitigation measures during the next 11 years to a value of anywhere between $11.9 million and $20.3 million to avoid those losses. These numbers depend on economic growth, oil prices, and a loss in transportation volume due to climate change impacts.
Did you know?
$43 billion worth of good involved in international trade move through Atlantic Canada annually.
Information on impacts to transportation came from the following studies:
Economic Consequences of the Climate Change Impacts on the NB/NS Transport Corridor
By Yuri Yevdokimov (March 2013) http://atlanticadaptation.ca/
Economic Evaluation of Climate Change Impacts
on New Brunswick-Nova Scotia Transport Corridor
By Yuri Yevdokimov (2012) http://atlanticadaptation.ca/node/284
The Economic Cost of Future Flood Damages
The potential economic damage associated with increased flood risk has been calculated for the Sackville region. This information is important as it will affect how communities decide to adapt to climate change.
Past floods have certainly resulted in huge economic costs for the Town of Sackville and more recently the Village of Port Elgin. In the days following the April 1962 fresh water flood in Sackville damage estimates ranged from several thousand to one million dollars. Several weeks later the estimated cost of damage was refined to a total of $197,000. In today’s dollars that would equal over $1.4 million!
More recent damage in Port Elgin totalled $900,000 from a single storm surge event in January 2010.
To calculate the economic cost of damages from future flood events the following has been considered for the Town of Sackville:
• 5 different climate scenarios
• Depth of flood waters and duration of flood
• Assets at risk (eg. residential, commercial and public properties, contents of properties, agricultural crops, and vehicles, as well as less tangible aspects such as human illness, clean-up costs, business disruption, temporary displacement, emotional stress, etc.)
• Market value of vehicles, types of vehicles owned
• Types of crops grown on agricultural land and their market values
• Probability of storms and floods happening in each month and which crops would be impacted in each month
• Potential adaptive strategies (a stakeholder group discussed what people might do to adapt and how to prepare and offset the costs of damages ahead of time)
Economic costs were calculated for the following agreed upon adaptation strategies:
1 Doing nothing
2 Raising the height of the dykes
3 Moving infrastructure outside high risk areas
4 Mixed Strategy (both raising dykes and relocating)
Each of these adaptation scenarios were examined and were compared to determine the rough cost of damages that might be avoided by using each strategy.
The Cost of Doing Nothing
If the Town of Sackville does nothing new to adapt to climate change the expected annual cost could be nearly $1.5 million. As climate change intensifies, these costs are expected to increase to nearly $1.7 million by 2025, just over $2.1 million by 2055, and over $3.1 million per year by 2085. Over the next 100 years, if the climate futures occur as forecasted, the total present value of the expected annual damages is $59.3 million.
Raising the Dykes
Discussion with local dyke experts suggested that a dyke top-up strategy could be reasonably implemented over a five-year period, subject to available funding. Proposed cost for dyke top-up is a little over $1.2 million including a new dyke behind the CN rail line.
It is important to note that the structure of the dykes prevents them from being topped up continuously. Because of the way Acadian settlers built the dykes over 200 years ago they can only support being raised to a certain height, and then no more.
The option of raising the dykes is not as simple as topping them up over and over again.
A relocation strategy involves moving infrastructure out of high risk areas. The strategy would require some policy research and development to determine the most effective and efficient way to relocate high risk assets. A number of policy mechanisms could be explored ranging from direct purchase of land by government to using tax or other incentive mechanisms to encourage individuals to relocate from high risk areas to low risk areas. Depending on the type of mechanism used, the costs could vary significantly. The researchers assume that land purchase would be used (at fair market value) which would cost roughly $19.7 million. However, this would be implemented over an assumed 20 year implementation period between 2025 and 2045. Therefore, the present value of these costs, assuming land purchase is implemented evenly over the 20 year period, would be $10.3 million.
Costs associated with the mixed scenario would be the sum of both relocation and dyke top-up scenarios.
In summary, for the Tantramar Region, and Sackville in particular, despite the costs involved in adaptation options, the price of not doing anything, especially when we now know what climate change has in store for us, is so much higher, as depicted in the graph above.
The Tantramar area has been involved in agriculture since the 1670s when Acadian settlers first arrived in the area and began dyking the marshes to use the fertile soil. Since these early days agricultural activities have been impacted by floods and storms, most notably the 1869 Saxby Gale (see excerpt below). In addition, there have been other floods over the years such as one in 1917 which filled the marshes with water as shown in the photos on the next page.
Excerpt from “The storm”
Featured in The Borderer, Sackville, N.B.,
October 14, 1869
It has been estimated that not over 2,000 tons of hay have been destroyed. This loss, great as it is, to our hard working farming people, will not be so severely felt now as the loss of the English grass next season, for there can be no doubt that wherever the salt water has touched English grass lands, their productiveness has been destroyed for one season at least. As the fencing has been entirely swept away, renewing it will be a heavy item. Thus the loss in hay to many is most ruinous, and the high price of labor will make the re-erection of dykes the most expensive and burdensome. The marsh proprietors have decided, we understand, not to erect any dykes this fall. In this they are quite wise, for the great majority of marshes will, we are satisfied, feel vastly the benefit of a winter’s run of tides, and heavy crops in the future will tell of the rejuvenating effects of this flood. Indeed, our farmers, as a rule, are most unreasonably afraid of a dash of salt water and mud, considering it is to them alone that we owe the fertility of our marshes.
“Clearly adaptation and mitigation will need to be made around the globe, and Sackville is no exception.”
Mel Jellett, Department of Geography and Environmental Studies, Mount Allison University
Much of the agricultural land in the Sackville area is in low-lying dyked land in the direct path of storm surges and sea level rise. Apart from potential flooding, there is a long list of impacts and stresses that climate change is predicted to bring to agriculture around the world:
• Limited availability of water
• Loss of biodiversity
• Air pollution
• Reduced resilience
• Soil erosion
• Increased salt content in irrigated areas
• Over-extraction of ground water
• Growing susceptibility to disease
In Sackville there are 80 farm operators comprising a total area of 8,436 ha and worth a total of $26,127,037 (based on total farm capital). See the agricultural land use map on the next page for the location and types of farms.
There are pros and cons for agricultural production in the Tantramar Region when it comes to climate change.
Climate Change Related Opportunities for Tantramar Farms
• Opportunity to grow a wider range of crops
• A longer growing season
• Grow higher yielding crops
Climate Change Challenges for Tantramar Farms
Faster growing weeds
Introduction of new invasive weeds and pests
Heat stress will affect milk production in cows
Sea level rise and storm surges could flood fields with salt water for days
Increased use of fertilizer, herbicides and pesticides because of increased temperatures and periods of drought
More frequent droughts during the growing season make irrigation essential for most high-value crops
An increasing number of storms producing heavy rainfall may delay spring planting and damage crops and soils
Investment in new farm equipment and storage facilities as shifts are made to grow new crops
Adaptation strategies to combat climate change can be costly
What is the risk of floods on farmlands around Sackville?
A 7 m flood would roughly affect 35% of the agricultural land in and around the town of Sackville. This number jumps dramatically with a 9 m flood event, where dykes would be overtopped and close to 93% of farm land would be flooded.
Source: Jellett, 2012
Information in this section is based on the following study:
Agricultural Adaptation Strategy for the Tantramar Region
By Mel Jellett (2011) http://atlanticadaptation.ca/node/282
Residents of Tantramar may experience health impacts due to climate change. In particular, the Town of Sackville’s sewage treatment ponds share a wall with the dyke. If a storm surge overtops or breaches the dykes and floods the sewage ponds, raw sewage could spill onto the streets of Sackville creating a severe health emergency. Sewage could also back up into houses in the town. Flooding could also disperse chemicals and fuel stored on commercial and residential properties anywhere in Tantramar.
Furthermore, studies are being conducted to understand the impacts of climate change on the distribution of Lyme disease-carrying ticks. The distribution of these ticks has changed in certain parts of Canada, including New Brunswick. Warmer temperatures could bring more ticks, as well as other pests and diseases to our region.
Dr. Vett Lloyd, Associate Professor in Biology at Mount Allison University, is currently studying the distribution of ticks and rate of Lyme Disease in southeast New Brunswick. Residents are urged to collect ticks they find on themselves or their dogs and submit them to Dr. Lloyd. For more information please contact firstname.lastname@example.org or 364-2509.