ANTECEDENT WAVE CONDITIONS EXPLAIN BEACH ACCRETION ASSOCIATED WITH STORMS

A method to account for the role of antecedent wave conditions on cross-shore movement of sand on beaches is introduced. The method is an adaptation of research by Wright, Short, and Green (1985), but has been simplified. An approach, which leads to the concept of the Ω (fall velocity parameter) versus Ω plane, is adopted. The plane helps identify when the beach should be stable and when the beach is in a state of disequilibrium. Disequilibrium is expected to cause erosion when the present wave conditions are more energetic than the antecedent conditions, and accretion when the present conditions are milder than the antecedent conditions. This concept is referred to as the Antecedent Beach Condition (ABC) model. Both lead line and CRAB survey data collected during SandyDuck were used to test the model. Lead line data strongly supported the model, including the concept of beach recovery with relatively energetic wave conditions during the waning storm period. CRAB data is more ambiguous and further investigation is now underway.