FIELD SURVEY AND NUMERICAL SIMULATION OF BEACH DEFORMATION NEAR DETACHED BREAKWATER AT AOYAMA BEACH IN NIIGATA COAST DURING THE APPROACH OF TYPHOON LUPIT (2021)

Abstract

 The field survey and numerical simulations of morphological changes associated with the typhoon Lupit (2021) were carried out near the detached breakwaters at Aoyama beach, Niigata coast. The topography and bathymetry data were obtained by UAV photogrammetry, RTK-GNSS and GPS sonar when we carried out field survey. Numerical simulations of morphological changes were performed by XBeach. As a result of numerical simulations, erosion in the land area and deposition in sea area near shoreline were calculated, which is consistent with the field survey. In addition, Brier skill score (BSS) was employed to quantitatively evaluate the simulated morphological changes. BSS was higher in the case where the observation of water level was used than that in the case where the astronomical tide levels were employed. Finally, salient was formed behind the breakwaters in the numerical simulation under the influence of diffracted waves and nearshore currents associated with the typhoon.