A Laboratory Study of Levee Scour from Overtopping Storm Waves and Protection for Robust Desgins

Levee failure due to scouring has been a prominent occurrence among intense storm surges and waves, giving rise to the implementation of various scour protection measures over the years. Several experiments were performed on a model levee on either bare levee soil or with a scour protection measure covering the soil. The purpose of this study is to breakdown the dynamics of levee scour due to overtopping waves and suggest efficient methods in reducing the amount of scour. The levee soil was made up of a sand-clay mixture and placed in a laboratory wave tank that created a constant wave overtopping simulation that mimics the field. The scour length was found to reach equilibrium before scour depth. Parameterizations were developed for values of maximum scour depth and scour length while reaching equilibrium and at equilibrium. From these equations, the maximum scour depth and scour length in the field can be calculated with knowledge of the densimetric Froude Number value. The riprap cover layer proved to be more effective than the coreloc cover layer. The presence of an underlayer proved to take precedence, however, on the overall effectiveness of the both protection measure types. It is recommended that the placement and size distribution of the underlayer be adjusted in the field to take advantage of its efficiency and receive economical advantages.