Field observations of nearshore bar formation

 

The formation of an inner nearshore bar was observed during a high-energy event at the sandy beach of Vejers, Denmark. The bar accreted in situ during surf zone conditions and the growth of the bar was associated with the development of a trough landward of the bar. Measurements of hydrodynamics and sediment fluxes were obtained from electromagnetic current meters and optical backscatter sensors. These process measurements showed that a divergence in sediment transport occurred at the location of the developing trough, and observed gradients in cross-shore net sediment flux were consistent with the morphological development. The main cause for the flux gradients were cross-shore gradients in offshore-directed mean current (undertow) speed which depended upon local relative wave height and local bed slope.