2024 Volume 80 Issue 17 Article ID: 24-17132
Marked beach changes occurred since 2012 at Nagama-hama Beach on Kurima Island located in the southwest part of Miyako Island as well as the beach changes at a sand spit extending at the Yonaha Bay mouth. A natural sandy beach composed of coral sand was eroded away at Nagama-hama Beach, and the sand spit, originally extended northward, elongated in the direction of NNE. The beach changes were analyzed using satellite images along with the field observation. On the basis of the observation records at Meteorological Observatory at Miyako Island, the course of typhoons since 2012 and resulting strong wind velocity and direction were investigated, selecting large typhoons affected Miyako Island. It was found that when large typhoon propagated northward in the sea east of Miyako Island, strong wind blew from the WSW or SW direction along the southwest coast of Miyako Island, resulting in strong wind waves from these directions. It was concluded that beach changes were triggered by these strong waves during typhoons.
