Longshore transport estimation on ofir beach in Northwest Portugal: Sand-tracer experiment

This work aims to shed some light on longshore sediment transport (LST) in the highly energetic northwest coast of Portugal. Data achieved through a sand-tracer experiment arecompared with data obtained fromthe original and thenewre-evaluated longshore sediment transport formulas (USACE Waterways Experiment Station's Coastal Engineering and Research Center, Kamphuis, and Bayrambulk formulas) to assess their performance. The field experiment with dyed sand was held atOfir Beach during one tidal cycle under mediumwave-energy conditions. Local hydrodynamic conditions and beach topography were recorded. The tracer was driven southward in response to the local swell and wind- and wave-induced currents (H_sb = 0.75 m, T_p = 11.5 s, θ_b = 8-12°). The LST was estimated by using a linear sediment trans-port flux approach. The obtained value (2.3 × 10^-3 m³. s^-1) approached the estimation provided by the original Bayram formula (2.5 × 10^-3 m³. s^-1). The other formulas overestimated the transport, but the estimations resulting from the new re-evaluated formulas also yield approximate results. Therefore, the results of this work indicated that the Bayram formula may give satisfactory results for predicting the longshore sediment transport on Ofir Beach.