Shortwave sand transport in the shallow surf zone

Empirical parameterizations of the shortwave sand transport that are used in practical engineering models lack the representation of certain processes to accurately predict morphodynamics in shallow water. Therefore, measurements of near‐bed velocity and suspended sand concentration, collected during two field campaigns (at the Sand Engine and Ameland, the Netherlands) and one field‐scale laboratory experiment (BARDEXII), were here analyzed to study the magnitude and direction of the shortwave sand flux in the shallow surf zone. Shortwave sand fluxes dominated the total sand flux during low‐energetic accretive conditions, while the mean cross‐shore current (undertow) dominated the total flux during high‐energetic erosive conditions. Under low‐energetic conditions, the onshore‐directed shortwave sand flux scales with the root‐mean‐square orbital velocity urms and velocity asymmetry Au but not with the velocity skewness. Under more energetic conditions the shortwave flux reduces with an i...