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The 1997 flood event in the Red River basin: Causes, assessment and damages

2015; Taylor & Francis; Volume: 41; Issue: 1-2 Linguagem: Inglês

10.1080/07011784.2015.1004198

1918-1817

W. F. Rannie,

Fire effects on ecosystems

In May 1997, the Red River Valley of Manitoba, North Dakota and Minnesota experienced a record flood which came to be known as the “Flood of the Century”. Prospects for only moderate flooding were completely transformed by a major snowstorm in the first week of April. Record snow and rain over the entire basin upstream of Winnipeg produced record discharges all along the river. At Winnipeg, the peak discharge was about 50% greater than the previous highest measured flow and was probably the second largest event in two centuries of documented flood history. At its peak, about 1840 km2 in Manitoba were inundated in a water body 100 km long with a maximum width of about 40 km. In Manitoba, 27,400 people were evacuated and damages and costs exceeded CAD $500 million (and were possibly closer to $1 billion). Nevertheless existing flood control structures, flood proofing and damage reduction programs, and emergency measures prevented losses which would have been truly catastrophic in Winnipeg. Furthermore, the peak stage might have been even greater except for manageable flows on the Assiniboine River and favourable weather during the flood itself. In the United States where flood control/flood proofing measures were less well developed, damages were many times greater and almost three times as many people were evacuated. The legacies of the flood in Manitoba include a CAD $665-million program to increase flood control and flood proofing for Winnipeg to the 700-year flood level. In the Red River valley outside Winnipeg, ring dikes were constructed around eight previously unprotected communities, individual properties were diked or elevated on pads, and flood proofing standards throughout the valley were raised to 0.6 m above the 1997 peak stage.