Short-term sand coarsening process in a backshore between headlands

Field observations of backshore topography and sand grain size were conducted from December 2003 to February 2005 at the Aotsuka Beach facing the Pacific Ocean in Japan, in order to investigate both wave and wind impacts on backshore processes at an eroded beach between artificial headlands. The beach was nourished in the measurement period but its effect on the backshore was limited. Instead, during a storm in January 2005, sand was coarsened remarkably in the seaward part of backshore just after large waves; and successively coarsened landward of the coarsening area in February. The sand coarsening processes could be explained from both wave and wind actions that coarse sand was transported to wave run-up area by large waves and then to the landward by strong landward winds, similarly to an accreted natural beach.