Soft cliff recession under oblique waves: physical model tests

Laboratory experiments have been performed to investigate the recession of soft cliffs due to oblique wave actions. The experiments were conducted in a wave tank with irregular waves. A test cliff was constructed of wet sand and (in one test) a sand/clay mixture, which was found to be appropriate for simulating the principal failure mode of soft cliffs fronted by erodeable beaches. The recession process is characterized by the following sequence: toe erosion—cliff failure—erosion of debris—toe erosion. The recession of the cliff top was measured from still photographs taken by an overhead camera. The longshore and cross-shore extents of individual failures and the time interval between two successive failures are obtained.