Morphological variations of a mixed sediment beachface (Teignmouth, UK)

The purpose of this study is to analyse the variations of the beach morphology surveyed in Teignmouth, United Kingdom, while the swash processes were shaping the beach, in parallel with the hydrodynamic conditions and watertable fluctuations. These data and field observations lead to a conceptual model which shows a three-phase sequence of evolution. The first phase is characterised by a quick erosion, which is linked with the sediment characteristics of the beachface. The second phase consists of a period of accretion caused by the influx of the sediment mobilised by the plunging breakers at the toe of the beachface, and finally, the seepage of the ground water induces the last phase of erosion mainly due to the enhanced backwash erosion. This model enlightens the importance of the grain characteristics for the beachface evolution and complements the model of Duncan, in the case of high-permeability sediment.