United States Flood Loss Report - Water Year 2011

Abstract

th 2011) totaled $8.41 billion. This was 108% of the thirty year average (1981 -2010) of $7.82 billion (adjusted to 2011 inflation). There were 108 flood-related deaths (118% of the 30 year average of 94). Of these fatalities, 61 were vehicle related incidents, and 71 were attributed to flash flood events. 2011 was a year of record-breaking, prolonged floods along some of the nation's largest rivers, the Missouri, Ohio and Mississippi. Heavy precipitation from the previous fall and summer across the Northern Plains left soils saturated and streams running high before the winter freeze. Once frozen soils locked moisture in place, a snowpack nearly double the average began to accumulate, setting up the north central U.S. for unavoidable spring snowmelt flooding. By mid-April, several heavy rain producing systems stalled over the Ohio River and central Mississippi River Valleys. Record rainfall fell across a broad expanse from Tulsa, Oklahoma to Cincinnati, Ohio from April 15 to May 6 amplifying the snowmelt-induced flood wave heading southward from the Upper Mississippi River Basin. Flash floods associated with these storms caused 24 deaths across Oklahoma, Missouri, Arkansas, Louisiana and Tennessee in April and May. The Ohio River and the Lower Mississippi River experienced record flooding levels (last seen in 1937 and 1927, respectively) that lasted for well over a month. These well anticipated floods caused a total of $3.4 billion in direct damages, nearly half of the annual total. Two tropical systems impacted densely populated portions of the Mid-Atlantic and Northeastern U.S., Hurricane Irene and the remnants of Tropical Storm Lee. These events, happening just over a week apart in late August and early September, combined to produce 37 freshwater flood fatalities and at least $3.9 billion in direct freshwater flood damages from Virginia to Vermont.