Equilibrium Foreshore Slope and Cross-shore Sediment Transport Rate

Laksanalamai, J. and Kobayashi, N., 2025. Equilibrium foreshore slope and cross-shore sediment transport rate. Journal of Coastal Research, 41(5), 884–891. Charlotte (North Carolina), ISSN 0749-0208. The concept of an equilibrium beach profile is extended to estimate cross-shore sediment transport on a measured beach profile. The extended model predicts offshore and onshore sediment transport on the foreshore slope, which are steeper and milder, respectively, than the corresponding equilibrium foreshore slope. A laboratory experiment was conducted to evaluate the model. Equilibrium, steep, and mild foreshores were created on a beach consisting of fine sand and exposed to the same irregular waves. The steep foreshore eroded rapidly and reached equilibrium. Accretion and equilibration on the mild slope were gradual. The calibrated model predicts the measured sediment transport rates on the initial steep and mild foreshores with clear deviations from the equilibrium foreshore profile. The analytical model may eventually be generalized and become applicable to forecast short-term foreshore profile changes using long-term beach profile evolution data.