大規模河川の河口から放出される土砂の海底への沈降と堆積過程の計算 -大河津分水路の河口を対象として-

抄録

 Estuaries of the large river discharge river waters and sediment to the sea. The discharged sediment is mainly the wash load, which is affected by density currents, tide, inertia forces of river discharge. Sediment which has repulsive force in pure water, lost electrical charge when it meets sea water and finally made flocculation caused by molecular attractive force. To understand distribution of the sediment in sea bottom, above mentioned phenomena should be included in numerical simulation algorithm for sediment transport model. In this study, a numerical algorithm for sediment particle transport under the effects of flocculation is originated. The algorithm is mainly based on the Lagrangian method. The performance of the numerical method is confirmed by the Lock-exchange flow in laboratory scale case. Application of the method to field scale calculation is conducted for the Okozu diversion channel in the Shinano River mouth. Settling of the sediment through the pycnocline is visualized with high resolution.