Effects of typhoon event on distribution of turbidity maximum zone in a tidal estuary

Estuaries are key nodes of land-ocean interaction, the associated suspended sediment processes being crucial for global and regional material fluxes and environmental health. Within estuaries, there is commonly a reach where... [ view full abstract ]

Estuaries are key nodes of land-ocean interaction, the associated suspended sediment processes being crucial for global and regional material fluxes and environmental health. Within estuaries, there is commonly a reach where the water turbidity is markedly higher than both landward and seaward. This elevated suspended sediment concentration (SSC) is termed the estuarine turbidity maximum (ETM). The ETM has important influences on harbor siltation, ecological conservation, and biogeochemical dynamics. Jiulongjiang estuary is a small macrotidal estuary in southeast China coastal area, which is a typical example for estuarine ecosystem conservation and its response to catchment management. Observed results show that the tidal current is the main factor which controls the variations of SSC in ETM within the estuary under the normal condition. However, under the influence of typhoon event, the hydrodynamic action strengthen and the salt water intrusion enhanced, and the fresh water and sediment discharged from river system increased, which led to the complicated variations of the ETM. Under the normal conditions, the maximum width of ETM was about 10 km in spring tide. However, before typhoon landed, the maximum width of the ETM was about 14 km; after the typhoon landed, the maximum width of the ETM was more than 20 km, and during the low tide stage, the width of the ETM was still 19 km which was induced by high turbidity water input from river system.