Missouri River Flood of 1993: Role of Woody Corridor Width in Levee Protection

We investigated the relationships between levee damage and woody corridor along a 353-mile segment of the Missouri River in Missouri during the flood of 1993. Results indicated that woody corridors between riverbanks and primary levees played a significant role in the reduction or prevention of flood related damage to levees. Forty-one percent of levee failures in this segment occurred in areas with no woody corridor, while 74 percent and 83 percent of failures occurred where woody corridor widths were less than 300 feet and less than 500 feet, respectively. Median failure lengths with a woody corridor present were 50.3 percent shorter than median failure lengths with no woody corridor present. Levees without failures had significantly wider median woody corridor widths than levees that failed. Eligibility for the Corps of Engineers levee maintenance program was not a significant factor in the reduction of levee damage. Discontinuities in woody corridors played a role in 27.5 percent of the levee failures in the study segment. Smaller segments of the river valley were studied to determine if geomorphic differences influenced variations in the protective value of woody corridors.