Field observation of coastline in Kagawa and Tokushima Prefectures was carried out to investigate natural characteristics of river mouth bar, gravel beach and sand spit. Topographic features of river mouth bar formed by successive action of longshore sand transport were studied at the Yoda and Minato rivers. Beach erosion triggered by wave reflection due to the construction of the breakwater of Komatsujima Port was found at the Katsu-ura river mouth.
