U.S.- Italy Research Workshop on the

Hydrometeorology, Impacts, and Management of Extreme Floods

Perugia (Italy), November 1995

Hydraulics and EFFECTIVENESS OF LEVEES

FOR FLOOD CONTROL

Ben Chie YEN

Professor of Civil Engineering

University of Illinois at Urbana-Champaign

Urbana, Illinois 61801, USA

Levees have been used as a structural flood protection for several thousand years. Their effect and effectiveness have been debated periodically, most recently during and after the 1993 Mississippi River flood. Based on hydraulic principles it can be shown that for a given flood levees raise the water stage in the leveed channel and upstream of it. On the other hand, they may slightly lower the water stage downstream. Methods for channel capacity determination and identification of low-capacity bottlenecks suitable for levee or channel improvement are also discussed. Effectiveness of levees is site-specific. Usually it is more effective to use levees in conjunction with other structural and nonstructural flood control measures.