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This paper presents the modeling of mud accumulation in Tokyo Bay. The model consists of hydrodynamic, wave hindcasting, bed shear stress and multi-class sediment sub-models in order to simulate the sediment associated processes both in the water body and bed layer. The present model accounts for sediment transport, settling, deposition, resuspension, accumulation and burial sedimentation processes, and it is capable to reproduce the accumulation of muddy sediments. Following the concept of multi-class particle model, the bed characteristics, i.e. the spatial distributions of particle size and the water content ratio in bed materials, were computed and qualitatively verified with field investigation data. The computed spatial variation in mud accumulation rate, particle size distribution and water content ratio were consistent with field data. Some discrepancies were identified and discussed.

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Accumulation of soft mud (muck) at the head of Tokyo Bay is one of the major causes of deterioration of water quality and ecosystems. We conducted field observation of sediment quality and numericalsimulation of grain size distribution to reveal the mechanism of its accumulation, which will provide a suggestion forthe future restoration of its estuarine environment. We revealed the detailed variation in sediment quality and one of the causes is attributed to the lower decomposition rate of organic matter due to the long-term exposure to hypoxic waters along with the higher rate of accumulation of very fine particles reflecting hydrodynamic properties.DeNiro, M. J. and S. Epstein (1978): Influence of diet on the distribution of carbon isotopes in animals, Geochim.

Abstract. This study evaluated the potential of coastal trees to reduce flooding areas caused by waves with abnormal heights, such as storm surges, using a numerical model applied to idealized beaches. The study considered 5 factors that affect sensitivity of coastal areas to flooding: slope of the beach, bottom friction coefficient, length of tree lines, width of tree lines, and shape of tree areas. The results indicate that slope of the beaches can reduce flooding areas, as steep slopes can transform wave energy into potential energy. With regard to the friction coefficient, beaches with higher bottom friction factors will have fewer flooding areas. Relative to beaches with no trees at all, increasing the length and width of tree lines can reduce flooding areas by as much as 30%. However, the shapes of tree areas have no significant effect on flooding areas.