Vegetation on Levees
Woody vegetation growing on a flood control levee is perceived by many people as compromising levee strength. The original levee structure was designed to not have trees and shrubs growing on it. Nevertheless, there are many miles of flood control levees in the Central Valley with trees growing on them, due to a long history of no seepage or structural problems apparent on or around them. However, this situation is viewed as a threat to public safety by the US Army Corps of Engineers (ACE), ultimately responsible for levee performance.
Examining the logic of the possible problems that trees growing on the levee may pose has resulted in these web pages. There is a body of research and observations that tree roots growing into a levee support public safety by strengthening the levee's shear strength, protecting it from surface erosion, and discouraging burrowing rodents from residing in the levee. These web pages examine some of the misconceptions about vegetation on levees, describe how tree roots grow through soil, and explain how root system architecture can improve the strength and functioning of levees.
Overview of the most common ways levees eventually fail.
A look at the frequent misconceptions of vegetation growing on levees.
An explanation of how vegetation on levees can improve the strength and integrity of levee structure.