Although a berm in Bowness will have an impact on the environment, property values and communities downstream, Calgary’s Flood Resilience Plan suggests that a berm is the right decision to make. In tandem, flood barriers and projects upstream are suspected to “help reduce groundwater flooding and sewer backups even further by keeping water from flowing overland from the river into storm and sewer systems and basements.” Sandy Davis, a river engineer with the City of Calgary says, “the benefits of preventing some of that overland flow include less damage to yards and streets and in peoples houses, less financial loses and also less sewer backup.”
Calgary’s Flood Mitigation Measures Assessment indicates that for every dollar spent on flood related projects after the flood, the city will save around $10 in avoided flood damage.
According to the Flood Resilience Plan, “the proposed Bowness barrier protects more than 350 private properties as well as municipal infrastructure.”
Inevitably, one of the drawbacks to having a berm is that it will impact the surrounding environment — something that Mayor Ted Clugston, and the City of Medicine Hat found out when they built their berm.
Just like Calgary, Medicine Hat was affected by serious flooding in 2013. Roughly a quarter of the population had to evacuate out of flood zones. Shortly after, the city decided a berm was a necessary part of their flood mitigation strategy. Since then, Medicine Hat has completed the majority of their berm projects, but it was not easy.
"There were some difficult times. We cut down 1,000 trees, and I had to make that announcement because nobody wants to cut down trees,” says Clugston.
Bowness resident Jean Woeller stresses that many community members are concerned over the impact that a berm would have on the river ecosystems and wildlife that makes the neighbourhood so special.
Sandy Davis, a river engineer with the City of Calgary says “ecological and environmental impacts would be not only to the vegetation but also to the wildlife in the area.”
This is because having less vegetation will affect other species in the surrounding environment.
Dr. Mary Reid, a professor at the University of Calgary who specialises in ecology, says “the function of riparian [a riparian zone is the space between land and a river] vegetation I don’t think can be reconstituted in the berm situation.”
Another risk of developing berms is that it could negatively affect communities downstream. Communities like Montgomery, Point Mckay, Parkdale, Westmount, or even communities along the river downtown.
“Downstream, that water will be passing by a lot faster and will have less opportunity to leave the river and get into the surrounding sediments,” Reid says.
“The quantity and the speed of the water will be increased when you start controlling where water can go in that single channel.”
Reid explains that the trees along the river are reliant on periodic flooding to have enough water for growth and to move propagules (a vegitative structure that can become detached from a plant and give rise to a new plant) so that new trees can be introduced and established in the environment.
“Plants along rivers are providing structure, they alleviate the flow of the river, they input leaves which are food for a lot of invertebrates in the river and they often can work to minimise erosion and the movement of toxins of various kinds from the land into the water,” Reid says.
Inevitably, the direct impact to various plant species will impact animal life and the overall functioning of the ecosystem.
Davis explains that the city investigates all potential impacts to the environment in order to plan a barrier that minimises risk.
He explains that in order to reduce impact, their berm was designed to work around clusters of living trees.
Calgary also plans to avoid living trees where possible and to consult with homeowners to avoid cutting down any trees of special significance to them.
In fact, for this very reason, towns along the Mississippi are debating whether they should keep their flood mitigation measures.
In Rebecca Hersher’s article, she says that “scientists warn that the infrastructure meant to protect towns and farms against flood waters is making the problem worse.”
But in Calgary, the focus is on completing thorough research to ensure the berm will best serve the community.
“When we look at designing a flood barrier, we do a lot of computer monitoring to make sure that we understand how it will impact the future flow in the river once that barrier is built,” says Davis.
Calgary also started conducting geophysical surveys to learn about the geology and groundwater conditions in Bowness.
Davis explains that if the berm has any flood impact elsewhere, they will investigate and change the design to best mitigate those impacts.
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