The Canadian Imagination

What it means to be Canadian; examining and reworking Canada as a nation.

Sunday, April 17, 2011

Living on floodplains

Once again the Red and Assiniboine Rivers are rising, and once again the cry goes out for government funding for a more permanent solution.

There is no question that a permanent solution is needed, desperately: and is not disaster relief funding one of the primary purposes of central government? Would not a permanent solution to prevent future disasters be much more cost-effective than continual payouts each and every year? for flood damage which is all too likely to become ever worse?

Yet that being said: I don't know that those living in the region would like my solution.

It begins with expropriation of all privately-owned 100-year flood land, without exception. This part can be made over into a seasonal-use park if desired: but containing nothing which can be harmed by flooding or which can be torn loose to harm others downstream. We have had four record-setting Red River floods in the past two decades. There is no reason to think that this trend will not continue.

At the edge of the expropriated flood plain, build permanent flood-control measures, large-scale dykes, reroutings and such, to protect the territory beyond. Sandbags just won't cut it anymore.

Thus far, the Red River Floodway and its associated flood control system has successfully protected most parts of Winnipeg through some bad flood years. With the new expansion, it should be adequate for a 1 in 700 year event: which, unhappily, we ought to expect a bit sooner and more frequently than that. Yet Duff's Ditch was never designed to protect outlying communities. Most new flood control measures outside the Floodway system will need to rely more heavily on dykes and flood control gates, due to the relatively high aquafer level locally.

All major highways, roads, and rails within that territory should be rerouted around the dyke-protected area wherever possible, even if that requires further expropriation. Highway 75 will prove challenging, but should be doable.

Where rerouting is completely impossible and that particular piece of road or rail is essential (eg. parts of the Trans-Canada, parts of the CPR line), it will have to be raised above record spring flood levels, with construction capable of withstanding flood forces strengthened by floating ice. That will probably require a raised roadway on pillars, using the ice pack engineering of the Constitution Bridge. A double deck or a deck wide enough to accommodate both rail and road would kill two birds with one stone.

Another complementary approach to flood control in this region is to set up a system to sift out everything from flood debris to pack ice at regular intervals. Such an approach may reduce the chance of ice dam buildup further downstream, which would aggravate existing flood conditions.

Engineering a system such as this one is the least of the related costs. Even building it is still much cheaper than paying for the damage afterward. Politically, however, would it fly?

A heavy part of the costs would have to be covered federally: and Manitoba does not carry much number clout in the House of Commons. "Unnecessary" tax-funded projects are never popular these days, but maybe it could be considered a stimulus project? The road-rail raised deck would have to be a joint government-private project, with a proportional amount of the costs being borne by each, using a formula which takes into account profit as well as use. (Freight rail traffic, unlike passenger rail traffic, is profitable even without government subsidies.) Of course any proposal where a private company is required to pay its fair share of the costs is going to be extremely unpopular with that company.

As long as we are considering local waterways, Lake Winnipeg is the next local region of immediate concern. For now, the heavy algae blooms caused by heavy agricultural runoff are feeding record numbers of fish: but history tells us that within a very few years, these numbers will crest, then fall off abruptly. If nothing to reduce agricultural runoff is done before then, Lake Winnipeg will become a dead lake.

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