Study on formation mechanism of turbidity maximum zone and numerical simulations in the macro tidal estuaries

To illustrate the formation mechanism and movement characteristics of the maximum turbidity zone in the strong-tidal estuary,this study systematically investigated the main factors affecting the formation of the maximum turbidity zone and its response relationship with estuarine landforms in the well-mixed estuary by analyzing the measured data.By considering the effects of viscous fine sediment movement characteristics and the influence of salinity,this study developed a mathematical model of the maximum turbidity zone in the strong-tidal estuary,which was used to simulate the migration process of the maximum turbidity zone in the dry season of the Jiao (Ling) River.The results show that:the maximum turbidity zone in the strong-tidal estuary arises from the interactions of complex dynamic factors (e.g.,tidal wave deformation,saltwater-freshwater mixing,sediment flocculation and re-suspension) under certain estuary boundary and sediment conditions. Also,tidal wave deformation and sediment supply are the key factors affecting the formation of the maximum turbidity zone. In addition,this study revealed that simulations of the largest turbidity zone in the strong-tidal estuary should fully consider the all the factors,such as tidal current,saltwater-freshwater mixing,periodic movement of viscous fine sediment,flocculation and sediment compaction. The mathematical model can be used to study maximum turbidity zone in strong-tidal estuary.