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 da...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.展开更多
In an estuary,tidal,wave and other marine powers interact with the coast in different ways and affect estuary morphology as well as its evolution.In the Huanghe(Yellow) River estuaries and nearby delta,there are many ...In an estuary,tidal,wave and other marine powers interact with the coast in different ways and affect estuary morphology as well as its evolution.In the Huanghe(Yellow) River estuaries and nearby delta,there are many small sediment-affected estuaries with a unique morphology,such as the Xiaoqing River estuary.In this study,we investigated the special evolution and genetic mechanism of the Xiaoqing River estuary by analyzing graphic and image data with a numerical simulation method.The results show that NE and NE-E tide waves are the main driving force for sandbar formation.Sediment shoals have originated from huge amounts of sediment from the Huanghe River,with consequent deposition at the Xiaoqing River mouth.The lateral suspended sediments beyond the river mouth move landward.Siltation takes place on the northern shoreline near the river mouth whereas erosion occurs in the south.The deposits come mainly from scouring of the shallow seabed on the northern side of the estuary.Storm surges speed up deposition in the estuary.Development of the sediment shoals has occurred in two steps involving the processes of growth and further southward extension.Although the southward shift increases the river curvature and length,the general eastward orientation of the estuary is unlikely to change.Processes on the adjacent shorelines do not affect the development of the sediment shoals.The study presents a morphodynamic evolutionary model for the Xiaoqing River estuary,with a long-term series cycle,within which a relatively short cycle occurs.展开更多
文摘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.
基金Supported by the Knowledge Innovative Program of Chinese Academy of Sciences(No.KZCX2-EW-207)the National Natural Science Foundation of China(Nos.41106041,40706035,40676037,41076031)+1 种基金the Open Fund of the Key Laboratory of Marine Resources and Environmental Geology, SOA(No.MASEG200807)the Marine Scientific Research and the Open Fund of the Key Laboratory of Marine Geology and Environment, Chinese Academy of Sciences(No.MGE2009KG04)
文摘In an estuary,tidal,wave and other marine powers interact with the coast in different ways and affect estuary morphology as well as its evolution.In the Huanghe(Yellow) River estuaries and nearby delta,there are many small sediment-affected estuaries with a unique morphology,such as the Xiaoqing River estuary.In this study,we investigated the special evolution and genetic mechanism of the Xiaoqing River estuary by analyzing graphic and image data with a numerical simulation method.The results show that NE and NE-E tide waves are the main driving force for sandbar formation.Sediment shoals have originated from huge amounts of sediment from the Huanghe River,with consequent deposition at the Xiaoqing River mouth.The lateral suspended sediments beyond the river mouth move landward.Siltation takes place on the northern shoreline near the river mouth whereas erosion occurs in the south.The deposits come mainly from scouring of the shallow seabed on the northern side of the estuary.Storm surges speed up deposition in the estuary.Development of the sediment shoals has occurred in two steps involving the processes of growth and further southward extension.Although the southward shift increases the river curvature and length,the general eastward orientation of the estuary is unlikely to change.Processes on the adjacent shorelines do not affect the development of the sediment shoals.The study presents a morphodynamic evolutionary model for the Xiaoqing River estuary,with a long-term series cycle,within which a relatively short cycle occurs.
