Shoreward transport of sand originally supplied from the offshore zone of the tidal flats, while forming a slender sand bar, and the landing of such sand were observed on the Kutsuo coast, where very wide tidal flats develop. Although this landward sand movement due to waves on the shallow tidal flats is part of the returning process of sand transported offshore by river currents during floods, its mechanism has not yet been studied. We investigated this phenomenon by considering the Kutsuo coast as an example. Then, we performed numerical simulation using the BG model to predict such shoreward sand movement. The observed phenomena were successfully explained by the results of the numerical simulation.

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  Beach changes of the Kamakura coast including Zaimokuza and Yui-ga-hama Beaches were investigated using past aerial photographs and bathymetric survey data. On this coast, sand back pass using windblown sand at a rate of 600 m³/yr has been carried out as well as beach nourishment. However, the effect of these activities have not yet clarified. Therefore, beach changes were predicted using the BG model proposed by Serizawa et al. to evaluate the effect of the sand back pass and beach nourishment.

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  Echo-sounding data obtained at 200 kHz for bathymetry survey was examined to measure the spatial variation of sediment size at the Hasaki Coast of Japan facing the Pacific Ocean. The comparison between the intensities of the sound waves reflected from the bottom and the median sediment diameters on the bottom surface at 12 points shows that the reflection intensity became large and exceeded a threshold value when the median sediment diameter was larger than 1 mm, and hence this method can be used to detect very coarse sand and gravel. The regions where the reflection intensity exceeded the threshold value and thereby the existence of very coarse sand or gravel was suggested were located at troughs, which result is consistent with a previous study's result.

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  Bathymetric changes in a widespread area between the Tenryu River mouth and Imagire inlet of Lake Hamana on the Enshu-nada coast were investigated using the bathymetric survey data. In this area, two large troughs stationary develop with the shoreline recession behind them. The shoreline was stable in the beach nourishment area using gravel but offshore seabed was gradually eroded because of lack of sand supply. Initial profile of a uniform slope became a concave profile and such eroded area has been expanding westward.

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  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.

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  Beach changes of Shichiri-ga-hama Beach facing Sagami Bay was investigated using past aerial photographs and bathymetric survey data. The shoreline next to Point Inamura-ga-saki was severely receded with a shoreline recession up to 35 m since 1963. The breakwater of Shonan Port was extended by 1963, resulting in formation of wave shelter zone in the lee of the breakwater, and westward longshore sand transport was induced by the formation of wave shelter zone. Measured beach changes were reproduced using BG model proposed by Serizawa et al.

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  On the Ichinomiya coast located in the south part of Kujukuri Beach, ten artificial headlands have been constructed since 1983. By 2010, part of these headlands has been completed but the rest of them are still under construction. The shape of these headlands is classified into T-shaped and jetty-type, and characteristic beach changes occurred around these headlands depending on their shape. The shoreline changes around these artificial headlands were investigated on the basis of the aerial photographs, and typical shoreline changes were summarized.

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  Shore protection countermeasures against dune and beach erosion near a large-scale structure are investigated through field and laboratory measurements. Field survey of the position and the height of dunes on the Miyazaki Coast revealed rapid development of steep scarp face in a region over several kilometers with a significant rate of retreat reaching 4m/year. On the basis of a series of laboratory experiments, the placement of geotextile sand tubes with an anti-scour sheet was found to be effective to mitigate the dune erosion. The use of a submerged jetty combined with submerged detached breakwaters was found to be effective in decreasing the sand entrapment near the structure and thus mitigating nearby beach erosion.

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  Shoreline and land use changes on a pocket beach south of Hirakata fishing port in Ibaraki Prefecture were investigated. On this beach, excess land reclamation was carried out to widen the land for parking lot as well as the construction of groins. Such construction triggered beach erosion because of the change in wave field. Beach changes between 1986 and 2009 were investigated using aerial photographs. Site photographs in 2001 before the construction of coastal structures and in 2011 after the construction clearly show the beach changes. Finally natural sandy beach of this coast was totally lost.

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