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Flood memories

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I’m not sure how many people know about the past floods of the Lower Fraser Valley, in 1972, 1948, and in 1894. Nor do I expect many people would recognize this map, below: what the Lower Mainland looked like before the era of land reclamation. Notice the large Sumas Lake sitting smack in the middle of Abbotsford – this is all flood-prone land. Likewise, Pitt Meadows used to be referred to as Pitt Polder.

Sumas Lake map 100

The 1948 flood required the evacuation of 16,000 people and damaged or destroyed 2000 homes. The freshet of the Fraser, caused by rapid snowmelt, peaked on June 10th, causing extensive flooding from Chilliwack to Mission. The river reached an elevation of 7.6 m at the Mission gauge. The waters breached a dozen dykes, putting a third of the flood plain, or 22,000 hectares, under water, including parts of Rosedale, Agassiz, and Chilliwack. Railways and roads were impassable, completely isolating Vancouver. The damage at the time was estimated at $20 million (over $210 million in today’s currency).

fraserflood7858386_orig

The 1972 flood crested at 7.1 meters on June 16, again as a result of a huge snowfall the preceding winter. Thankfully dykes held through most of the Lower Fraser Valley, and only parts of Surrey were under water. (Upstream, things were worse, when a dyke failure in Kamloops caused substantial flooding.)

The largest flood occurred in May 1894, with much of the Lower Fraser floodplain under water, from Harrison to Richmond. The waters crested at Mission at 7.85 meters. (What is remarkable is how high the river was despite the fact that there no dyking system to speak of back then, and the river could spread over the whole flood plain. A flood of this magnitude, hemmed in by dykes, would be much higher – and a breach far worse. According to the Fraser Basin Council, a similar flood has a one in three chance of occuring within the next 50 years.)

People balk at the costs of proposed improvements to our dyking system. I wish there was better awareness of the risks, and past history.

Hamburg has suffered its own series of devastating floods. The flood of 1962 is etched in Hamburg’s collective memory: on February 16, a storm surge of 5.7 meters breached dykes in sixty locations, taking the city by surprise and submerging low-lying parts of the city, killing 347 people. This was far from the first destructive flood in Hamburg; historical records starting in 1248 report five catastrophic floods. But the 1962 caused a full reassessment of flood control measures – higher dykes and better advance warning. As a result, the flood of 1976, which was even higher, passed without loss of life.

A flood marker downtown Hamburg.

A flood marker downtown Hamburg.

Two markers along the beach along the Elbe (there is no 1976 marker downtown - maybe thanks to the 1969 markers)

Two markers along the beach along the Elbe (there is no 1976 marker downtown – maybe thanks to the 1962 markers)

Throughout the city are reminders of the floods. High water marks can be seen all along the river, including downtown. Our friends there are certainly aware of the markers – and that flooding is always a possibility. I’m not aware of such flood markers in the Lower Mainland (there’s a nice one in Kamloops). It’s too bad; they would have a great educational value.

______________

On March 24 the Provincial government announced a new $16.6 million initiative to reinforce dikes along Richmond and replace some of the old pump houses.  That’s wonderful.  The press release claims that a repeat of the 1894 flood would cause $7.1 billion in damages.  Indeed.  Much as I applaud the initiative, I wish it was accompanied by a few permanent markers like those in Hamburg.  People comparing flood markers with the height of their roofs may be less inclined to complain about government spending and taxes.

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Written by enviropaul

February 1, 2016 at 5:24 pm

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