Like all rivers, the size of the peak flow of the Red River varies considerably from one year to the next. Some years the peak flow is below the average while in other it is in excess of it. Occasionally, the peak flow is far in excess of the average and there is an extreme flood, as occurred in 1997. The 20 largest floods of the Red River since 1800 are listed in the linked table. The magnitudes of the 1826, 1852 and 1861 floods are estimated based on a reconstruction of the maximum levels of flooding conducted in the 1870s by order of Sir Sanford Fleming, Engineer-in-Chief, Canadian Pacific Railway (CPR), who recognized the flood hazard in the area.
Between 1948 and 1999, there has been a greater incidence of extreme Red River flows than in the period from 1892 to 1947. This is readily apparent in the two linked graphs below, one (A) which depicts the peak flows and a five year running mean of peak flows, and the other (B) portraying the cumulative departures from the mean peak flow. Data in the graphs is for the "Red River at Redwood Bridge", station number 05OJ001). In graph A, note that the discharge level of 2000 m3s-1 was exceeded 11 times in the 1948-1999 period, but only twice between 1892 and 1947. The cumulative departures from the mean graph (B) indicates that peak flows have been tended to be above average after about 1945, far more than in the 1897-1945 period. These trends are not unique to the Red River, but also occur on other Prairie rivers systems. They reflect variations in climate between the first and second halves of the twentieth century.
Known flood disasters in Manitoba during the twentieth century are listed in the linked table. Flood "disaster" is an ambiguous term, but in the context of flooding it reflects the inability of a community(s) to cope with the impacts of a flood event. Since this is a list of disasters, it is important to recognize that this is not a comprehensive listing of flood events per se in Manitoba, because all floods do not result in "disasters".
The table lists 18 twentieth century flood disasters for Manitoba. Ten of these relate directly to the Red River, including the well-known floods of 1950 and 1997. Although the flood that caused the 1950 disaster is the second largest flood of the twentieth century, the floods of 1979 and 1996 were only slightly smaller in magnitude. However, these floods had a much lesser impact due to well-organized emergency flood measures and the construction of flood protection infrastructure (e.g., Red River Floodway, Shellmouth dam, Portage diversion and permanent diking).
The Emergency Preparedness Canada definition of a disaster is "an interruption in time and space of normal processes causing death, injury or homelessness, economic or property lose, and/or significant environmental damage. The interruption is beyond the coping capacity of the community and/or is beyond the assumed risks of human activity. Assumed risk is inherent in most human activity such as transportation and handling of dangerous goods. The interruption precludes war." Emergency Preparedness Canada is the federal agency that safeguards lives and reduces damage to property by fostering better preparedness for emergencies in Canada.
This table was extracted directly from and can be referenced to Brooks et al. (in press). Although modified, the data originated from an Emergency Preparedness Canada database and is used with permission.
Brooks, G.R., Evans, S.G. and Clague, J.J.
In press: Flooding chapter; in Natural Geological Hazards in Canada: a Synthesis; (Brooks, G.R., editor), Geological Survey of Canada Bulletin 548.