BEACH CHANGES AT NORTH END OF YABUCHI ISLAND ASSOCIATED WITH CONSTRUCTION OF CAUSEWAY IN SOUTH PART OF KIN BAY

Abstract

 When a wave-sheltering structure is constructed in a wave field where waves are incident from two directions, the wave action from one direction disappears in the wave-shelter zone, and otherwise balanced sandy beach will deform significantly. Such beach changes can take place on coral reef coast such as that in Okinawa, and the impact of the construction reaches the nearby coast. One of the examples can be seen after the construction of Irab Bridge connecting Miyako and Irabu Islands. The same changes occurred in Kin Bay in Okinawa after the construction of a causeway. In this study, the effect of the construction of a causeway was investigated using aerial photographs and field observations.