Abstract
Beach changes of the Yotsukura and Natsui coasts facing the Pacific Ocean were investigated using the past aerial photographs. The shoreline changes on a pocket beach with an approximately 10 km length since 1947 were read from these aerial photographs. Yotsukura fishing port was constructed at the north end of the pocket beach with the extension of the offshore breakwaters. After their construction, wide wave shelter zone was formed south of the breakwater, resulting in sand deposition near the fishing port and severe beach erosion south of the fishing port. As a measure, concrete armor units were placed along the shoreline, resulting in the disappearance of natural sandy beach.
