Morphodynamics of swash bars in mesotidal exposed beaches of SW Spain

Morphological monitoring of swash bars at different temporal scales was carried out in the southatlantic Spanish coast between Chipiona and Rota. As a result, the main morphometric and morphodynamic characteristics of more than 60 bars were determined. The differences between this type of bars and the classic ridge and runnel were also pointed out. Bars associated with dissipative beaches appeared to be flat, with no siginificant avalanche face. Bars associated to low reflective beaches presented a better development while bars associated to rocky shore-platform beaches showed similar morphologies to those of low reflective beaches. Inner sedimentary structures of bars in dissipative beaches showed laminae parallel to the beach face. When the bars were located at the upper beachface, the avalanche faces showed clear foreset laminae. In this environment, morphodynamics is controlled by different processes depending on wave characteristics, bar form and water level fluctuations during tidal cycles. The temporal distribution of bars is marked by a higher frequency in spring, and lower one in autumn.