摘要
The Jiaoiang Estuary is shallow, macro-tidal dominated and extremely turbid, with a larger variation of the freshwater discharge. The estuarine stratification and classification are analysed by using a set of field data observed in wat season.In spring tide, the depth-mean peak tidal currents can reach 2 m/s. During flood tide the water column is vertically hamogeneous, but the horizontal salinity gradient is large and there is a fresh water front. A 1 m thick fluid mud layer capped by lutocline is formed when the tidal current is less than 0. 3 m/s. As the low-salinity trapped in the fluid mud layer, underlying saltier water enhances vertical mixing when the fluid mud layer is eroded and the water column is only slishily stratified during ebb tide.During neap tide, the tidal currents are reduced, two lutoclines exist in the vertical profile of suspended sediment conentration (SSC ) for a long time and its positive contributions to the water column stability are 17 times larger than tha of maximum salinity gradient observed in our previous study. The water column is stratified and the fresh water front which exists in spring tide is lifted as a salt wedge in neap tide.The dynamics of the fine sediment is so important in the extremely turbid estuary that the estuarine classification does not fit in with the field data when the scheme of the estuarine classification proposed by Schultz and Simons (1957) is applied in the Jiaoiang Estuary.
The Jiaoiang Estuary is shallow, macro-tidal dominated and extremely turbid, with a larger variation of the freshwater discharge. The estuarine stratification and classification are analysed by using a set of field data observed in wat season.In spring tide, the depth-mean peak tidal currents can reach 2 m/s. During flood tide the water column is vertically hamogeneous, but the horizontal salinity gradient is large and there is a fresh water front. A 1 m thick fluid mud layer capped by lutocline is formed when the tidal current is less than 0. 3 m/s. As the low-salinity trapped in the fluid mud layer, underlying saltier water enhances vertical mixing when the fluid mud layer is eroded and the water column is only slishily stratified during ebb tide.During neap tide, the tidal currents are reduced, two lutoclines exist in the vertical profile of suspended sediment conentration (SSC ) for a long time and its positive contributions to the water column stability are 17 times larger than tha of maximum salinity gradient observed in our previous study. The water column is stratified and the fresh water front which exists in spring tide is lifted as a salt wedge in neap tide.The dynamics of the fine sediment is so important in the extremely turbid estuary that the estuarine classification does not fit in with the field data when the scheme of the estuarine classification proposed by Schultz and Simons (1957) is applied in the Jiaoiang Estuary.
