Red River Floodway

The Red River Floodway (French: Canal de dérivation de la rivière Rouge) 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).[1][2]

Part of a series on the
Red River of the North
The Red River drainage basin, with the Red River highlighted
Major Floods
Geology
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Red River floodway at the southeast corner of the Winnipeg city limits near Lorette as seen from the air. The Trans Canada Highway and Canadian National Railway bridges over the floodway can be seen, along with the Perimeter Highway.

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. Since its completion in 1968, the Floodway has prevented over $40 billion (CAD) in cumulative flood damage.[3] 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.[4]

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

Construction of the Floodway started on November 27th, 1962 and finished in March 1968. The construction was a major undertaking with 76.5 million cubic metres (2.75 billion cubic feet) of earth excavated—more than what was moved for the Suez Canal.[5][6]

At the time, the project was the second largest earth-moving project in the world – next only to the construction of the Panama Canal.[7] The total cost at the time was $63 million (CAD), equivalent to approximately $505 million today.

Design
Control gates at the inlet to the Floodway
Bridge over the control gates

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 "Brunkild Z-dike" extending to the west from the south of the city. The Brunkild Dike was built in 1997 during the "Flood of the Century," when the volume of water exceeded the safe capacity of the Floodway and water lapped within inches of the city's dikes. 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 2,550 m3/s (90,000 cfs) 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.[8]

The Brunkild dike 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. In 2003, the province announced plans to expand the Floodway, increasing its flow capacity from 1,700 m3/s (60,000 cu ft/s) to 4,000 m3/s (140,000 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.

Year Peak Flow (cfs) Peak Flow (cms)
1997 66,400 1,880
2009 43,100 1,220
1979 42,000 1,190
1996 38,800 1,100
1974 36,700 1,040
2011 36,700 1,040

Expansion

Since the 1997 Red River flood resulted in water levels that took the existing floodway to the limits of its capacity, various levels of government commissioned engineering studies for a major increase in flood protection for the City of Winnipeg. Work began in late 2005 under a provincial collective bargaining agreement and has included modifications to rail and road crossings as well as transmission line spans, upgrades to inlet control structures and fire protection, increased elevation of existing dikes (including the Brunkild dike), and the widening of the entire floodway channel. The NDP government set aside a portion of the construction budget for aboriginal construction firms.[9] The Red River Floodway Expansion was completed in late 2010 at a final cost of more than $665,000,000 CAD. Since the completion of the expansion, the capacity of the floodway has increased to 4,000 cubic metres (140,000 cubic feet) per second, the estimated level of a 1-in-700 year flood event. (Using the flow rates of Niagara Falls as a standard of comparison, this is more than double its average of 1,833 cubic metres and about a third over its maximum.) The expanded floodway now protects over 140,000 homes, over 8,000 businesses, and will prevent more than $12 billion (CAD) in damage to the provincial economy in the event of a 1-in-700 year flood.

Criticism

The NDP government was criticized by Conservatives for forcing construction companies to unionize. Brian Pallister, then the Member of Parliament for the Portage—Lisgar constituency and future Manitoba premier, told parliament, "the Manitoba NDP government is planning to proceed with a plan to force every worker on the Red River floodway expansion to unionize, despite the fact that 95% of Manitoba's construction companies are not unionized."[10]

The diversion of flood water impacts rural communities negatively. For example, in 1997 Emerson, Morris, St Adolphe and the surrounding farm buildings and lands ended up with the bulk of the flood water in order to save Winnipeg from flood damage (Bone, 2018).[11] In 2011, the Manitoba government intentionally diverted water from the Assiniboine River to save Winnipeg which ended up flooding communities around Lake Manitoba - The communities of Pinaymootang, Lake St. Martin, Little Saskatchewan and Dauphin River were severely impacted, as well as the surrounding farmland and cottages.[12]

Considerations in the United States

In 2009, the North Dakota city of Fargo has been contemplating building their own floodway, or diversion channel, similar to the Red River Floodway.[13][14] This is in response to the disastrous floods of 1997 (nicknamed "The Flood of the Century"), and in early 2009.

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See also

Notes
  1. "Red River Floodway". Manitoba Government - Flood Information. Government of Manitoba. Retrieved 27 July 2017. The expansion of the current floodway system (including the West Dike and channel outlet) began after the 1997 flood, to protect the City of Winnipeg from a one-in-700-year flood. It increased the floodway's capacity - from 90,000 cfs (cubic feet per second) to 140,000 cfs.
  2. Cash, Martin (26 April 2014). "Red River Floodway expansion debate flows on". Winnipeg Free Press. Retrieved 26 April 2014. Open shop (non-union) construction companies bid on and effectively completed work that increased the capacity of the Floodway from 1,700 cubic metres of water per second to 4,000 cubic metres.
  3. "Red River Floodway". Manitoba Government - Flood Information. Government of Manitoba. Retrieved 27 July 2017. Since 1968, it has prevented more than $40 billion (in 2011 dollars) in flood damage in Winnipeg.
  4. Red River Floodway. Canadian Register of Historic Places. Retrieved 10 June 2012.
  5. Cash, Martin (4 July 2008), "Floodway dubbed engineering marvel", Winnipeg Free Press
  6. "Official Opening of the Red River Floodway" (PDF). Government of Manitoba: News Archive. Government of Manitoba. Retrieved 27 July 2017.
  7. “A Tribute to Roblin’s Vision Archived 2012-06-22 at the Wayback Machine”, Manitoba Floodway Authority, Province of Manitoba, last accessed on 2009-03-26.
  8. "Proposed Floodway Expansion Project Environmental Assessment" (PDF). Province of Manitoba. August 2004. Retrieved 26 April 2014.
  9. "Archived copy". Archived from the original on 2011-07-08. Retrieved 2010-06-24.CS1 maint: archived copy as title (link)
  10. https://openparliament.ca/politicians/220/?page=17
  11. Bone, 2018, R. M. (2018). The regional geography of Canada. Vancouver, B.C.: Langara College.
  12. https://aptnnews.ca/2018/01/12/manitoba-judge-approves-90m-flood-compensation-settlement/
  13. Mayeda, Andrew (29 March 2009). "Dakota cities may mimic Winnipeg floodway". canada.com. CanWest Publishing Inc. Archived from the original on 11 March 2010. The floodway is one of the main reasons Winnipeg suffered less damage in 1997 than such upstream communities in North Dakota as Grand Forks, said Donald Schwert, a geology professor at North Dakota State University."You’re going to be seeing a lot of people from Fargo going up and having a good look at the Winnipeg floodway after this," he said.
  14. Fargo may look to Grand Forks and Canada for Relief. Canwest News Service 29 Mar 2009; Retrieved 4 July 2014

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