RECOVERY OF SANDY BEACH AND SPAWNING SITE FOR SEA TURTLE - EXAMPLE OF NAGAYAMA BEACH ON IRABU ISLAND

Abstract

 Irabu Bridge under construction has a causeway at the connecting point to Irabu Island, which formed a wave-shelter zone on the nearby reef and longshore sand transport was induced by the wave-sheltering effect of the causeway. Beach was severely eroded on the south coast of the bridge. Measures using three groins and beach nourishment were taken in 2012. After the completion of the measures, sandy beach was recovered and the spawning of sea turtle was started again. These situations were investigated by field observations along with the comparison of the aerial photographs and the numerical simulation results with the measured.