Image from a new report on sea level rise from the City of Campbell River.

Seawater could eventually cover downtown Campbell River due to climate change-fueled floods

City planning for long-term flood mitigation as rising seas threaten buildings and infrastructure

Higher sea levels driven by climate change could cause extensive flooding in coastal areas of Campbell River by 2100, and plans are underway to reduce the risks, according to a new report from the city.

Municipal officials organized two workshops last week to field questions from the public about the findings, and to get feedback about how to adapt to changes on the coastline.

Flood mitigation infrastructure will develop gradually, said Amber Zirnhelt, the city’s manager of long-range planning and sustainability.

“It will be long-term, slow process,” she said. “We’re not talking about tomorrow going and building a big seawall along Campbell River.”

The two-part report describes a number of practices used around the world to deal with sea-level rises, ranging from offshore reefs to seawalls to homes elevated on piles.

David Reid, an architect working with the city on sea-rise planning, described some of the pros and cons of those techniques during a presentation at Willow Point Hall on Nov. 29. Dikes, for example, tend to block the scenery.

“If your house is low and the dike is high, then you can’t see the view anymore, which is highly undesirable,” Reid said.

And more importantly, dike failures can lead to widespread deaths, something that’s occurred in the Netherlands, he said. For that reason, policymakers frequently ask people to sleep at a level higher than the crest of the dike.

“If the dike fails, we don’t want you to die,” Reid said.

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It’s the kind of consideration that more coastal communities will be wrestling with as they plan for the future.

Sea rise is practically inevitable, said Grant Lamont, a coastal engineer with Northwest Hydraulic Consultants, which was hired by the city to study ocean dynamics.

“There’s less and less uncertainty today within the scientific papers and scientific community that sea-level rise is going to happen,” he said. “The uncertainty is about when.”

The flood projections are based on a one-metre rise in sea levels by 2100 in combination with elements including a major storm event, king tide, storm surge and wave action, Zirnhelt said.

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The report indicates that if nothing were done to prepare for that kind of scenario, water would flood a large section of downtown, stretching across the lower parts of Hwy. 19A, Dogwood St., Shoppers Row and other streets.

Water would also hit various public works, including communications and electrical utilities that run underground. The downtown fire hall would also be affected.

In Willow Point and south – an area “very exposed to high storm winds and waves from the open reaches of the Strait of Georgia” – water would hit various utilities and the lower floors of some buildings and low yards. The boat ramp would be at risk, along with the grounds and boathouse of Sybil Andrews Cottage.

Surging seas would squeeze out habitat and walking areas along the foreshore, and rock armouring would be at a greater risk of “failure or overtopping due to increased wave height,” according to the report.

Elsewhere in the city, public beach areas at Sequoia Park and nearby low-lying buildings and parking areas would also be affected by rising seas, and sanitary gravity sewers would be at risk.

Erosion may also affect the stability of steep slopes along the stretch of coastline between Evergreen Rd. and the Maritime Heritage Centre.

READ MORE: UN chief issues dramatic climate appeal to world leaders

In North Campbell River, key risks include water hitting the lower floors of several buildings in the Agricultural Land Reserve along with damage to pocket beaches and sensitive shoreline areas.

The bluffs area would also be at risk of erosion and slides, which could in turn threaten the sites of existing homes, along with utility and stair routes.

The report notes that greenhouse gas emissions due largely to human activity are the primary driver of sea-level rise, as higher temperatures cause thermal expansion of ocean waters and accelerated melting of ice sheets and glaciers.

In Campbell River, the effect of rising oceans is checked somewhat by a slight upheave of the area’s land mass, but “sea-level rise is happening faster than the land is rebounding,” the report states.

The one-metre figure comes from provincial guidelines based on projections from the UN’s Intergovernmental Panel on Climate Change (IPCC), which brings together experts from around the world to assess published literature about climate change and to provide information to governments.

Several governments are already planning for a 1.6 metre rise, and B.C.’s one-metre figure may be revised upwards as new information becomes available, Zirnhelt said.

“We have to plan with that factor of uncertainty in mind,” she said.

@davidgordonkoch
david.koch@campbellrivermirror.com

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