The coastal zone management has to be generally in harmony with protections, environments and utilizations of coast areas. Changes of cross-shore profiles in sandy beaches will have considerable influence over the coastal zone management in particular. The relation among the shoreline, the long-shore bar and the stable point of cross-shore profiles is discussed by field data in Japan coast and the site plan of offshore breakwater, artificial reef, etc. is proposed in this paper. Cross-shore profiles of sandy beaches are changed by factors of incident wave, water depth, near-shore current, beach material, etc. The data of waves, tides, beach materials, bottom sounding charts surveyed in fields for the past few years was used to investigate cross-shore profiles of sandy beaches along coasts of the Sea of Pacific, the Sea of Okhotsk and the Sea of Japan in Hokkaido of Japan. Results are as follows; 1. A stable point where the sediment transport was not moved remarkably on the bottom slope existed on cross-shore profiles obtained by overlapping sounding charts of every season and year. 2. The sediment transport was mainly moving between the shoreline and the stable point. 3. The sand bar arising between the shoreline and the stable point was influenced by the wave reflection from sandy beaches. 4. On-offshore movements of the sand bar were classified by advancing or retreating of the shoreline. 5. The water depth of the sand bar crest was in proportion to the water depth of trough on-shore side of the sand bar. 6. The sand bar was closely related to the position of the shoreline and the stable point. 7. The sand bar was moved for the shore by constructing the offshore breakwater for accretion. 8. It is good to construct the artificial reef on the position of sand bar, and set up harbor or fishing port entrances off the coast of the stable point.
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