The Red River Floodway is an artificial flood control waterway in Western Canada. It is a 47 km (29 mi) long channel which, during flood periods, takes part of the Red River's flow around the city of Winnipeg, Manitoba to the east and discharges it back into the Red River below the dam at Lockport. It can carry floodwater at a rate of up to 140,000 cubic feet per second (4,000 m3/s), expanded in the 2000s from its original channel capacity of 90,000 cubic feet per second (2,500 m3/s). The Floodway was pejoratively nicknamed Duff's Ditch by opponents of its construction, after Premier Duff Roblin, whose Progressive Conservative government initiated the project, partly in response to the disastrous 1950 Red River flood. It was completed in time and under budget. Subsequent events have vindicated the plan, leading to the nickname becoming an affectionate one. Since its completion in 1968, the Floodway is estimated to have prevented over $40 billion in cumulative flood damage. It was designated a National Historic Site of Canada in 2000, as the floodway is an outstanding engineering achievement both in terms of function and impact. From south to north, the Floodway passes through the extreme southeastern part of Winnipeg and the rural municipalities of Ritchot, Springfield, East St. Paul, and St. Clements.
History Following the submission of the Royal Commission report Manitobans were strongly divided as to whether the province could afford the capital costs of a mammoth engineering project that would benefit primarily Winnipeg. The project was championed by Dufferin (Duff) Roblin, the Leader of the Opposition and head of the Manitoba Progressive Conservative Party, but it was vehemently denounced by opponents as a monumental, and potentially ruinous, waste of money. Indeed, the projected Red River Floodway was derisively referred to as “Duff”s Folly” and “Duff’s Ditch”, and decried as “approximating the building of the pyramids of Egypt in terms of usefulness.” The construction of the floodway and Assiniboine River works, would entail a capital cost of over $72 million, amortized over fifty years at 4% interest, at a time when the province had a population of only 900,000 and an annual net provincial revenue of about $74 million. Following the formation of a new provincial government in June 1958, Duff Roblin, the newly elected Premier of Manitoba, continued to promote the floodway, and managed to secure a commitment from the federal government of Prime Minister John Diefenbaker to pay up to 60% of the construction costs. Construction of the Floodway started on November 27, 1962, and finished in March 1968. The construction was a major undertaking with 76.5 million cubic metres (2.70 billion cubic feet) of earth excavated—more than what was moved for the Suez Canal. At the time, the project was the second largest earth-moving project in the world – next only to the construction of the Panama Canal. The total cost at the time was $63 million, equivalent to approximately $505 million today.
Design
The Floodway protection system includes more than just the channel to the east of the city, but also the dikes along the river through Winnipeg and the West Dike extending to the southwest from the floodway inlet. Primarily as a result of the Floodway, the city suffered little flood damage. After the 1997 flood, a 2004 re-assessment of the floodway and its channel capacity indicated that 2,500 m3/s (90,000 cu ft/s) could be passed through the floodway during a major flood, but this is considered above the design capacity as it would submerge bridges, and the decision was made to further expand the floodway. Although the term "floodway gates" is used for the control structure, this is a misnomer as the gates are actually on the Red River as it enters the city and not on the floodway channel. When Red River flows exceed what can safely be handled by the river channel within the city, the gates begin to close by rising up out of the river bed, to the degree needed, restricting water flow into the city to manageable amounts. The resulting upstream back-up of the Red River then flows into the adjacent floodway entrance, diverting the excess flow that could not be safely handled by the river channel within the city. Under flood conditions, even when the floodway is in operation, the Red River within the city will still carry greater than normal amounts of water and some local flood mitigation measures still may be required within the city. The rise in river levels upstream of the gates when in operation needs to be contained by a diking system. The West Dike which extends to near the village of Brunkild is the limiting factor on the volume of water that can be diverted around the city, as a result of the extremely low grades in the area. This dike was urgently extended by 42 km from its previous western terminus near Domain MB in 1997 to prevent flood water from doing an end run around the original dike. In 2003, the province announced plans to expand the Floodway, increasing its flow capacity from 1,700 to 4,000 m3/s (60,000 to 141,000 cu ft/s). It was decided to widen the Floodway as opposed to deepening it because of the soil and ground conditions in the area. Many underground aquifers in the area are used for drinking water for rural residents and the aquifers could potentially be contaminated if the floodway were deeper. There is also potential for pressures to increase in the aquifers, causing a "blowout" to occur, where water would flow from the aquifers in the ground to the surface and reduce the capacity of the Floodway. Officials decided widening the floodway would be the best option despite the lower hydraulic capacity that would result.
Flow rates Below are the peak flow rates recorded on the Red River Floodway since it was completed in 1968.
… excerpt ends here. Continue reading the full article.
