椒江河口高混浊水混合过程分析

MIXING PROCESS IN HIGHLY TURBID WATERS OF JIAOJIANG RIVER ESTUARY

根据199年洪季的实测资料分析了高度浑浊的椒江河口的混合过程，并探讨了水动力学和沉积动力学因素对河口混合的重要作用。调查研究表明，椒江河口最大浑浊带下的高浑浊水一浮泥层厚达1m，高浑浊水-浮泥层与上覆水之间是泥跃层。泥跃层与高混浊水-浮泥层对水体稳定的作用比同期观测到的盐跃层大17倍以上。当高浑浊水-浮泥层被侵蚀时，在高浑浊水-浮泥层中的低盐水体又增加了水体的垂向混合能力。

The Jiaojiang River Estuary is shallow, macro-tide dominated, highly turbid, and has large freshwater discharge variations. The mixing processes include phenomena such as freshwater front, salt wedge and vertical negative salinity gradient. This paper presents the analyzed result of the mixing processes in Jiaojiang River Estuary and the effects of both hydrodynamics and fine sediment dynmics using a set of observational field data collected in April, 1991.During spring tidal flood, the water column is verically homogenous, but has a freshwater front in the estuary. A lm thick fluid mud layer capped by a lutocline is formed when the tidal current velocity is less 0.3ms-1. The low-salinity water trapped in the fluid mud layer underlying more salty water enhances vertical mixing when the fluid mud layer is eroded.During the neap, two lutoclines exist in the water column for 80%-90% of observation time in two tidal cycles. The lutocline's contributions to the water column stability are 17 times larger than that of the maximum salinity gradient ever observed throughout our study. The water column is stratified due to the lutoclines and the high suspended sediment concentions inhibiting the vertical mixing. The freshwater front present in spring hde evolvedinto a salt wedge.