The history of flooding in the Great Plains displays a marked diversity of types. Most common are short-lived flash floods on small watersheds following intense cloudburst storms. Less common, but usually more destructive, are longerlived main-stem river floods. These result from heavy rains dispersed over a wide area, fast ice and snowmelt, or a combination of both. On Northern Great Plains streams, ice dams during the spring runoff also lead to flooding. No stream escapes flooding. It is part of a river's natural processes. The primary response of humans to these floods has been through engineering: dams, levees, drainage channels, and land-use modification. Yet the underlying reason humans in the Great Plains have repeatedly suffered from floods is their tendency to occupy floodplains.
Three of the most dramatic and devastating flash floods in the Plains were those of June 1921 on the upper Arkansas; May 1951 on the Little Nemaha at Syracuse, Nebraska; and June 1972 at Rapid City, South Dakota. In the first case, moisture-laden winds blowing westward created a swirling vortex against the Front Range above Pueblo, Colorado, on June 3, 1921. Torrential rains fell from orographic cooling, producing flash floods on the upper Arkansas during the next two days. Pueblo residents stood on the town's levees to watch the flood along the straightened and channeled river that ran through the business district. An unknown number of people lost their lives when flood crests topped the levees; seventyeight bodies were eventually recovered.
Another example of a cloudburst flood was the record-breaking (in terms of discharge per drainage area) flood on Nebraska's Little Nemaha River at Syracuse on May 8-9, 1951. It was caused by runoff arriving together from two intense thunderstorms over separate watersheds. The flood flow from this event was 225,000 cubic feet per second from a watershed of 218 square miles. Twenty-three people died, and among other damages, sloping fields on uplands lost topsoil in depths "up to the plow sole," while fields at places down on the floodplain were covered by five feet of that topsoil.
A historical benchmark of flood devastation in the Plains was the flood of June 9, 1972, at Rapid City, South Dakota. An intense stationary supercell thunderstorm in the Black Hills dropped up to 15.5 inches of rain–close to the average annual amount–in six hours in the hills to the west of Rapid City. Failure of a dam brought a flood crest on Rapid Creek through town near midnight. Its flood flow was ten times the previous flood record. Homes, businesses, and 5,000 automobiles were destroyed, more than 3,000 people were injured, and 237 died.
Wider areal precipitation produced two of the most devastating floods in the Central Plains. Following a month of above-average rainfall in the watershed, extremely heavy rains fell–up to twenty inches in places–on the south fork of the Republican River in eastern Colorado and western Kansas during the night of May 30–31, 1935. More than 100 people lost their lives, 20,000 head of livestock drowned, and massive destruction of railroad tracks, bridges, and levees occurred. The high loss of life in the upper valley resulted from the arrival of the flood in the middle of the night, with little or no warning. After daylight, many others died when they refused to heed warnings and tried to save livestock and personal belongings.
The 1951 flood of the Kansas and Missouri Rivers at Kansas City followed intense widespread rainfall in the Kansas River basin. The watercourse through Kansas City was notoriously constricted, with much of the industrial district protected behind twenty-foot levees. At the time much of the flood protection work authorized under the Pick-Sloan Plan remained incomplete. After floodwaters topped the levees, nearly $1 billion in damages was sustained. The Missouri at Kansas City also flooded in 1993 when heavy summer rains over much of the Midwest caused the most devastating flood in U.S. history to the Mississippi River basin. Part of this extraordinary event was the particularly severe flooding on the lower Missouri, which brought a river crest at Kansas City on July 27 at nearly three feet above the devastating 1951 flood level.
The Red River of the North holds a special place in the history of Great Plains flooding. As the major northward-flowing river in the United States, it is subject to a distinctive flood potential. Spring floods occur as snow at the headwaters to the south begins to melt. These waters pool behind ice dams to the north. Because the river flows in a relatively flat valley (the bed of ancient glacial Lake Agassiz), the waters rise gradually. A great flood in 1897 followed this pattern, and repeatedly damaging floods have occurred in the cities of Grand Forks, Fargo-Moorhead, and Winnipeg. Movie newsreels in 1950 followed the slowly rising waters, sandbagging efforts, and flooding that went on for weeks across Manitoba in the Red and Assiniboine River valleys. Provincial and dominion governments wrestled with responsibility and assistance in the face of the unprecedented disaster. Southern Manitoba had 530 square miles inundated. Television news in 1997 showed the dramatic burning of Grand Forks's flooded downtown when the Red River flooded on both sides of the border. This flood produced a "Red Sea" in Canada nearly as large as Lake Manitoba. Canadians responded with the enormous engineering project of the Greater Winnipeg Floodway, a twenty-six-mile diversion ditch. Its construction required moving an amount of dirt equal to that of the Panama Canal.
Will Guthrie University of Kansas
Bumsted, J. M. Floods of the Centuries: A History of Flood Disasters in the Red River Valley, 1776–1997. Winnipeg: Great Plains Publications, 1997.
Hoyt, William G., and Walter B. Langbein. Floods. Princeton: Princeton University Press, 1954.
Smith, Keith, and Roy Ward. Floods: Physical Processes and Human Impacts. Chichester, England: John Wiley & Sons, 1998.