Abstract
The contour-line-change model considering change in grain size proposed by Kumada et al.(2005) was applied to the Chigasaki coast, where beach erosion has taken place due to the effect of decrease in longshore sand supply. Bottom sampling was carried out. Depth distribution in median diameter and longitudinal profiles were measured. The grain size was divided into three dominant grain size populations such as fine sand, medium sand and gravel. The effect of beach nourishment using materials with different grain sizes was predicted. Optimum beach nourishment was the nourishment using materials composed of mixed grain sizes in terms of protection, environment and use of the coast.
