Robert Dean, Mathijs van Ledden


Overtopping of earthen levees can result in lee side erosion, levee failure and severe flooding consequences. Erosion takes time and early design guidance did not account for overtopping duration. The potential overtopping durations associated with hurricanes depends on the time histories of the surges and waves and are usually shorter than for riverine or coastal flooding by other storm types. With significant advancements in hurricane-induced storm surge modeling, it is appropriate to improve the levee erosion response characteristics. This paper presents the results of a blind-folded comparison of a method developed by Dean, et al (2010) to two levee locations in the New Orleans area. The levees failed in one area where the waves were larger than the second area where the levees performed well. The method applied accounts for surge and wave time histories, levee geometry and grass cover quality. Results are consistent with failure at the location of higher wave heights; however, the method also predicts failure at the location where levee function was retained. At the latter location, for good quality grass cover and a wave period of 4 s, a required levee crest elevation of 5.9 m is determined compared to an actual elevation of 5.8 m. For poor grass quality and a wave period of 8 s, the method indicates a required crest elevation of 7.4 m. The method can be applied to optimize levee design, for example, through investigating the trade offs between crest elevation and levee side slopes.


levee overtopping; levee erosion; hurricanes; duration


Akkerman, D. Barnadini, J. Van der Meer, A. Van Houen (2007) "Field Tests on Sea Defences Subject to Wave Overtopping", Proceedings, ASCE Coastal Structures Conference, Venice, Italy. PMCid:1899190

Dean, R. G. (1978) "Effects of Vegetation on Shoreline Erosional Processes," Proceedings, National Symposium on Wetlands, November, pp. 415-426.

Dean, R. G., J. D. Rosati, T. L. Walton and B. E. Edge (2010) "Erosional Equivalencies of Levees: Steady and Intermittent Wave Overtopping", Ocean Engineering, Vol. 37, pp. 104-113.

Hewlett, H. W. M., L. A. Boorman and M. E. Bramley (1987) "Design of Reinforced Grass Waterways", CIRIA Report 116, Construction and Industry Research and Information Association, London.

Hoffmans, G. G. J. Akkerman, H. J. Verheij, A. Van Hoven and J. W. Van der Meer (2008) The Erodibility of Grassed Inner Dike Slopes Against Wave Overtopping", Proceedings of the 31st International Conference of Coastal Engineering, Hamburg, Germany, pp. 2,944 – 2,956.

Kobayashi, N., A. W. Raichle and T. Asano (1993) "Wave Attenuation by Vegetation", J. Waterway, Port and Coastal Engineering, Vol.199, No. 1, pp. 30 – 48.

Lima, S. F., C. F. Neves, and N. M. L. Rosauro (2006) "Damping of Gravity Waves by Fields of Flexible Vegetation", Proceedings of the 30th International Conference of Coastal Engineering, San Diego, CA, pp. 491 – 503. PMid:16732283

Schüttrumpf, H. (2003) "Wave Overtopping Flow on Seadikes – Experimental and Theoretical Investigations", PIANC Bulletin 149.

U. S. Army Corps of Engineers (2008a) "Coastal Engineering Manual", Available at:

U. S. Army Corps of Engineers (2008b) "Performance Evaluation of the New Orleans and Southeast Louisiana Hurricane Protection System: Final Report of the Interagency Performance Evaluation Task Force", Available at:

Van der Meer, J. W. (2002) "Technical Report: Wave Run-up and Wave Overtopping at Dikes", Technical Advisory Committee on Flood Defence, (herein referred to as the "TAW Manual"), Delft.

Van der Meer, J. W., D. Bernardini, W. Snijders, and E. Regeling (2006) "The Wave Overtopping Simulator", Proceedings of the 30th International Conference of Coastal Engineering, San Diego, CA, pp. 4654 – 4664.

Van der Meer, J. W. (2008) "Erosion Strength of Inner Slopes of Dikes Against Overtopping: Preliminary Conclusions After Two Years of Testing With the Wave Overtopping Simulator, ComCoast, Rijkswaterstaat-Dienst Weg- en Waterbouwkunde, Rijkswaterstaat-Waterdienst, Projectbureau Zeeweringen.

Whitehead, E., M. Schiele and W. Bull (1976) "A Guide to the Use of Grass in Hydraulic Engineering Practice", CIRIA Report 71, Construction and Industry Research and Information Association, London.

Young, M. J. (2005) "Wave Overtopping and Grass Cover Layer Failure on the Inner Slope of Dikes", MSc Thesis WSE-CEPD-05.03, UNESCO-IHE.

Storesund, R., R. G. Bea and Y. Huang (2010) "Simulated Wave-Induced Erosion of the Mississippi River-Gulf Outlet Levees During Hurricane Katrina", Journal WPCOE, ASCE, pp. 177-189.

Van der Meer, J. W. (2002) "Technical Report: Wave Runup and Wave Overtopping at Dikes", Technical Advisory Committee on Wave Overtopping at Dikes. Technical Committee on Flood Defence. (Herein referred to as the "TAW Manual").

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