BEACH CUSP DESTRUCTION SEQUENCES OBSERVED UNDER EROSION AND ACCRETION CONDITIONS

摘要

Beach cusps are common features of steep reflective and intermediate beaches. While beach cusp formation has received much attention over the past decade, beach cusp destruction has generally been related to erosive conditions. Here we present two datasets of observations reporting beach cusp destruction for both accretive and erosive conditions. Data were collected at Grand Popo (Benin, West Africa). Daily topographic surveys allowed observation of the dynamics of beach cusp systems during two field experiments in 2013 and 2014 under rather similar wave and tide conditions. While destruction during the 2013 field experiment was associated with accretive conditions, destruction during the 2014 field experiment was associated with erosive conditions. The shape of the beach profile (convex-linear in 2013 versus convex-concave in 2014) together with the depth of the low tide terrace might be key factors (among others) explaining the differences observed in the dynamics of cusps rather than hydrodynamic forcing.