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Taitō-ku, Japan

Noshi Y.,Nihon University | Uda T.,Public Works Research Center
Proceedings of the Coastal Engineering Conference | Year: 2014

When beach changes occur owing to the imbalance of longshore sand transport, not only bathymétrie changes but also grain size changes occur, having an impact on the coastal environment. With the increase in the anthropogenic impact, such changes have been observed on many coasts. Here, the bathymetric changes and changes in grain size of seabed materials were investigated on the basis of a numerical simulation using the BG model (a three-dimensional model for predicting beach changes based on Bagnold's concept), with northern Kujukuri Beach in Japan as the study area. Source


Serizawa M.,Coastal Engineering Laboratory Co. | Uda T.,Public Works Research Center | Miyahara S.,Coastal Engineering Laboratory Co.
Proceedings of the Coastal Engineering Conference | Year: 2014

On a flat shallow seabed, sand spits and cuspate forelands with rhythmic shapes may develop and a barrier island can elongate alongshore, which significantly differs from the beach changes on coasts facing a deep ocean. In this study, the interaction between two circular sandy islands on a flat shallow seabed owing to waves was investigated by numerical simulation, focusing on the wave-sheltering effect of the islands themselves. The topographic changes caused by the interaction between two sandy islands were predicted using the BG model (a three-dimensional model for predicting beach changes based on Bagnold's concept). Source


Serizawa M.,Coastal Engineering Laboratory Co. | Uda T.,Public Works Research Center | Miyahara S.,Coastal Engineering Laboratory Co.
Procedia Engineering | Year: 2015

In a slender water body with a large aspect ratio, the angle of wind waves relative to the direction normal to the shoreline may exceed 45°, resulting in the emergence of cuspate forelands and the subdivision of a lake, because the fetch distance along the principal axis becomes large. The BG model (a three-dimensional model for predicting beach changes based on Bagnold's concept) was used to predict the segmentation of a rectangular lake by wind waves under the conditions with/without the construction of offshore breakwaters that reduce the fetch distance, together with the numerical simulation of the deformation of a circular lake when a straight seawall cutting off a part of the lake was constructed. © 2015 Published by Elsevier Ltd. Source


Uda T.,Public Works Research Center | Onaka S.,Chiyoda Corporation | Serizawa M.,Coastal Engineering Laboratory Co.
Procedia Engineering | Year: 2015

Beach changes near Pengambengan fishing port in the western part of Bali Island, Indonesia, were investigated by the analysis of satellite images and field observations. In this area, northwestward longshore sand transport prevails because of the oblique wave incidence from the Indian Ocean, and this longshore sand transport has been blocked by a fishing port breakwater, resulting in severe downcoast erosion. As a measure, a seawall has been constructed, instead of maintaining the continuity of the natural longshore sand transport. The adoption of this method caused further downcoast erosion. The sand bypassing method should be adopted to mitigate such erosion. © 2015 Published by Elsevier Ltd. Source


Kobayashi A.,Nihon University | Uda T.,Public Works Research Center | Noshi Y.,Nihon University
Procedia Engineering | Year: 2015

The impact of the removal of a river mouth bar as a measure against river mouth closure to the surrounding coasts was investigated, taking the Hota coast as an example. Also, on this coast, landfilling was extensively carried out to build a coastal road along the coastline, resulting in the narrowing of the natural sandy beach. These anthropogenic factors affected the overall shoreline on a pocket beach, devastating the natural coastal environment. We investigated the effects of these impacts using aerial photographs and field observations. © 2015 The Authors. Published by Elsevier Ltd. Source

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