Mississippi River Levee Failures: June 2008 Flood

Abstract

During the spring and summer of 2008, record rainfall in the Midwest United States led to severe flooding as water overtopped the levees bordering the Mississippi River and its tributaries. The erosion associated with the overtopping resulted in levee breaches in many places. After the flooding, a field reconnaissance team was sent to collect time-sensitive data and provide a comprehensive overview of the performance of the levees during the flooding. Two locations where levee overtopping occurred are particularly interesting because of their differing site conditions and performance. This paper presents the levee overtopping case histories of the Winfield-Pin Oak site which was overtopped and severe erosion led to failure, and the Brevator site which was also overtopped but did not fail. Included are a hydrological investigation, documented site conditions, geotechnical soil properties, a soil erodibility analysis, and the documented levee vegetative cover. Levee performance is influenced by the flood conditions, the site conditions, and the soil properties. Both sites in this study experienced large levels and durations of overtopping water, but it is proposed that the Brevator site survived because of its vegetative cover and more erosion resistant soils. Erosion is a very complicated phenomenon that cannot be described by any one parameter, but in all cases, dense and consistent native vegetative cover can greatly improve the overall levee performance.