At Kemigawa beach in Chiba Prefecture, the central part of the artificial beach has been eroded due to the wave sheltering effect of the curved groins built at both ends of the beach. As a countermeasure, gently sloping revetment was built in front of the existing seawall exposed in the eroded area. This accelerated loss of sandy beach due to the burying under the concrete slope, and the toe of the gently sloping revetment became slippery because of the attachment of marine organisms, disturbing usage of the coast. These situations were analyzed by field observation and numerical model.
