Abstract
Coral reefs well develop offshore of the west coast of Saipan Island. Managaha Island composed of coral sand is located on this reef flat. Large shoreline changes can be observed around the cuspate foreland located at the northwest side of the island. On August 27, 2017, field observation was carried out on this islet together with the investigation of wave climate around Saipan Island and shoreline variation of the island using satellite imageries. The shape of cuspate foreland on the island was classified into four types. The probability of the wave incidence from NE was high during February and April, and October and January, causing leftward longshore sand transport around the cuspate foreland, whereas the wave incidence from SW predominates during July and September, causing rightward longshore sand transport. It was concluded that the shoreline variation around cuspate foreland of this islet was due to these seasonal variations in wave direction.
