July/August 1998
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July/August 1998 |
by Bruce Rawson and Don Herndon
No one alive today can remember when the Red River flooded as it did in the spring of 1997. You have to go back to 1852 to find a comparable flood. In some areas of the basin nothing on record can compare. The people who lived through the 1997 flood will never forget the "flood of the century" when 103,000 people abandoned their homes as the river spread up to 40 kilometers (25 miles) wide. Downtown Grand Forks, North Dakota burned as the floodwaters flowed through the city. Smaller communities such as Ste. Agathe, Manitoba and Ada, Minnesota were inundated, as were unprotected neighborhoods of other towns and outlying homes. Property damage was immense; human costs even greater. And, it could easily have been worse.
The Red River Floodway, constructed after the devastating 1950 flood, diverted much of the floodwaters around Winnipeg, the largest city in the basin. If it had rained or the wind on the "Red Sea" had blown north, the floodway and dikes protecting the city would not have held. Large areas of Winnipeg could have suffered the same fate as Grand Forks.
The flood inspired the best of people and communities. They pulled together like never before to raise dikes and help each other. Tales of courage and personal sacrifice, even heroism, will be the stories passed on to future generations.
After Grand Forks flooded and the crest threatened Winnipeg, the Prime Minister and the President called for joint Canada-U.S. action. In June, Foreign Affairs Minister Lloyd Axworthy and Secretary of State Madeleine Albright asked the International Joint Commission to analyze the causes and effects of the Red River flood and to recommend ways to reduce the impact of future floods. The Commission established the International Red River Basin Task Force to investigate. The task force prepared an interim report on short-term measures to prepare immediately for the possibility of another flood. The Commission reported to governments on December 31, 1997, endorsing the task force's 40 recommendations. The Commission's investigation is among a number underway by state, provincial and federal agencies. It is the only one looking at the entire basin.
A simple but inescapable conclusion from the topography and the history of floods is that there are no "silver bullets" to protect the valley. The river is certain to flood again.
The Red River valley, the bed of ancient Lake Agassiz, is flat. The elevation from Wahpeton, North Dakota in the south to Winnipeg 400 kilometres (250 miles) further north drops just 75 meters (246 feet). The slope of the main stream averages about four centimetres per kilometre (0.2 feet per mile) near the border. The basin is about 100 kilometres (60 miles) across at its widest point. When conditions are right and the river floods, there is nothing to hold the waters back. The entire valley is the primary floodplain. The Red River becomes a "Red Sea."
The flow of the water is anything but straightforward. The direction of overland flows from tributaries becomes a dangerous, complicated puzzle. In the United States, overland floods hit Ada, Wahpeton/Breckenridge, and Grand Forks/East Grand Forks. In Ste. Agathe, the floodwaters flowed from the west, not from the river to the east of town. Predicting overland flooding is particularly frustrating because there are not sufficient gages and computer models to help forecast such events.
The 1997 flood was the largest flood in the 20th century. The next largest was in 1950 where the peak flow was 3,050 cubic metres per second (cms) at Winnipeg compared to about 4,580 cms in 1997. But even this was not the largest flood on record. The flood of 1826, which wiped out the Selkirk colony in Manitoba, was estimated to be about 6,370 cms. Even the 1852 flood was greater than this year's.
The Interim Report warned that those who survived the flood of the century might become complacent about the possibility of another damaging flood in the near future. This is no time for complacency. Floods on the scale of 1997 or larger could happen in any year. The odds may be small, but the risk must not be ignored. The report warned that flood preparedness must become part of the culture of the Red River valley.
The task force made recommendations on:
The report reviewed the capability to forecast floods and to plan for construction on the floodplain. The conclusion is that better information and new computer tools are critically important. And early warning is essential: less surprise means less damage.
The task force was directed to report to the Commission in the spring of 1999. It intends to conduct research and determine what needs to be done to prepare for and protect against future floods. On the basis of its investigations and comments presented at public meetings, the task force intends to explore water retention possibilities, floodplain management, transboundary flooding in the lower Pembina River, standards of flood protection and pollution and other environmental issues. The recommendations the task force and Commission draw from these studies will help governments in their preparations for future floods.
The task force also intends to develop computer models and the database to run them. These tools will be used to forecast the amount of water to expect and where it is going to go. This will be the legacy that will protect the people of the basin when the Red River floods again.
Bruce Rawson and Don Herndon are the Canadian and U.S. cochairs of the International Red River Basin Task Force. Copies of the report may be obtained at www.ijc.org/php/publications/html/taskforce.html on the World Wide Web or from a Commission office.
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Les gens qui ont vécu les inondations de 1997 n'oublieront jamais « l'inondation du siècle » au cours de laquelle 103 000 personnes ont dû quitter leur foyer lorsque la rivière Rouge a envahi les terres sur une distance allant jusqu'à 40 kilomètres (25 milles). À la suite d'une demande d'examen formulée par les gouvernements du Canada et des États-Unis, la Commission a créé le Groupe de travail international sur le bassin de la rivière Rouge, qui a rédigé un rapport provisoire sur les mesures à prendre à court terme afin de se préparer dans l'immédiat à l'éventualité d'une autre inondation. Ce Rapport provisoire nous met en garde contre la possibilité que ceux qui ont vécu l'inondation du siècle aient tendance à penser qu'il y a peu de risques qu'une inondation de cette envergure se produise dans un proche avenir. Or, il ne faut pas se faire d'illusion. Des inondations semblables à celle de 1997, ou encore plus graves, peuvent se produire n'importe quand. Les chances sont peut-être faibles, mais il ne faut pas négliger cette possibilité. Le Groupe de travail entend conduire d'autres recherches afin de déterminer ce qu'il faut faire pour se préparer à de nouvelles inondations et s'en protéger. On peut se procurer un exemplaire du rapport sur le réseau Internet à l'adresse www. ijc.org/boards/rrb/taskforcf.html ou en s'adressant à un bureau de la Commission.