Evaluation of total sediments movement on the Abukuma River and the Sendai Bay Coast

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1. Reexamining the results of field survey on the Abukuma River mouth morphology conducted by ourselves since 1984, sediment movement and sediment balance were studied from various time scale of view. It was shown that the estury have a function as a pocket for sediment and the time scale of sediment movement are controled by the ratio of this volume and the sediment flux by the external forces.2. A water runoff and sediment discharge of thle Abukuma River was modeled from the upper reach to the river mouth and the sediment supply from the river to the Sendai Bay Coast was reasonably evaluated.3. Morphology changes, sendiment characteristics and waves along the Sendai Bay Coast and the Fukushima Coast were examined and the sediment balance of the Sendai Bay Coast was evaluated quantatively.4. Combining the above results, the total sediment movement was evaluated both along the Abukuma River and the Sendai Bay Coast. It was pointed out that the Sendai Bay Coast was changed its state from dynamic equilibrium to the unequilibrium state because of lack of sediment supply and the obstraction of sand drift along the coast.5. The engineering measures were considered for the unequilibrium state of sediment along the Sendai Bay Coast.