Quantification of Beach Profile Change
1988
Larson, Magnus
An engineering numerical model is presented for simulating beach profile change in the surf zone produced by wave-induced cross-shore sand transport. It simulates the dynamics of macroscale profile change, such as growth and movement of breakpoint bars and berms. The foundation for development of the numerical model was two large wave tank experiments consisting altogether of 42 cases with different incident wave conditions, median grain size, and initial beach shape. Extensive analysis was made to define and quantify parameters describing profile change and relate these parameters to wave and sand characteristics. The model was developed using transport rate relationships inferred from profile change measured in the large wave tanks. Distributions of the net transport rate were obtained by integrating the sand conservation equation across pairs of profiles separated in time. Semi-empirical transport rate relationships were developed for different regions of the profile. The beach profile change model was calibrated and verified with the prototype-scale laboratory data. It was also applied to simulate field beach profile change measured in five storm events and good agreement was found. Beach profile evolution in the vicinity of a seawall and the adjustment of a beach fill to incident waves were also studied with the model.
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