Numerical modelling of wave overwash at low-crested sand barriers

In overwash beaches, response of a barrier profile as a whole to storm wave attacks can be distinguished into seaward and landward parts that are associated with two respective across-shore driving processes i.e. surge erosion, and overwash. Modeling of overwash relies heavily on the specification of wave overtopping from the seaside (see problem schematization in Fig.1). In return, overwash imposes a non-zero landward sediment transport rate and thus significantly modifies also the seaward profile, especially on the beach face area. This defers substantially from cases of high beach profiles where there is no or negligible transport in the landward direction. These two above cross-shore processes are therefore well interrelated and must be convoluted in one single model. In order to form the basis for the development of a numerical model of low-crested sand barriers response to wave attacks, two successive test series were carried out to increase physical insight into wave overwash. Low-crested condition corresponding to moderate to severe overtopping was selected for all the tests.