长江河口涨潮槽的形成机理与动力沉积特征
摘要
河口涨潮槽的研究不仅是河口动力地貌学和河口动力沉积学研究的重要内容和前沿课题，而且对港口选址、通海航道治理、护岸围垦以及河口综合开发利用都具有重要的研究和应用价值。本文依托国家自然科学基金课题《长江河口涨潮槽形成的机理与演化过程的定量研究》，以长江河口的涨潮槽为研究对象，采用沉积和地貌，定性和定量相结合的方法，运用GIS技术对河口涨潮槽的形成机理、演化模式、动力沉积特征以及冲淤变化等问题进行了系统的研究。
本文的研究工作主要包括：1．收集整理海图资料以及以前的有关实测数据；2．参加2001洪季和2003年枯季野外定点、走航观测和取样工作；3．进行大量的室内样品分析和数据处理工作，包括沙波资料的分析计算，矿物分析的样品预处理和上机测试，样品室内磁性测量，海图数值化和冲淤计算等。通过以上的研究认为河口涨潮槽的概念应该有更为广泛的含义，包括河口一切由涨潮流作用为主形成的负地形，如涨潮冲刷坑，涨潮冲刷槽和涨潮水道等，涨潮槽的特征应该保持多年。用优势流、优势沙、优势潮量、涨潮槽形态和净底沙运移方向的方法都可以表达涨潮槽的性质。
河口涨潮槽在涨潮优势流作用下，槽内表层沉积物的粒度、轻重矿物、微体古生物和磁学等特征不同于落潮槽相应的沉积特征，体现了沉积物的分布对河口复杂水动力的响应。
河口涨潮槽浅层沉积物粒度、轻重矿物、微体古生物和磁学性质的变化可说明涨潮槽在形成演化过程中沉积环境的变化。形成前沉积环境较为开敞，形成后由于沙嘴的阻隔作用使涨潮槽内环境较为封闭，因此在垂向上沉积物的性质不同。将~(210)Pb放射性测年方法应用于河口海岸环境时需慎重，虽然由于活度的变化无法准确确定垂向沉积物的沉积年代，但仍可给我们提供沉积物沉积时环境和水动力变化的信息。
用GIS方法计算1861-2002年新桥水道区域的冲淤变化，可定量表达涨潮槽在不同时间尺度形成演化规律，结合涨潮槽岩芯沉积物垂向的沉积特性变化，可阐明涨潮槽的形成机理与演化过程，并提出不同种类型涨潮槽的形成演化模式。
Study of a flood channel or flood-dominated channel of estuary is not only an important content in estuarine dynamic geomorphology and dynamic sediment, but also is a practical problem nearly related to the selection of harbor sites, regulation of sea-entering waterway, bank revetment and land reclamation, and even the comprehensive exploitation of estuaries. Supported by the State Natural Science Foundation Project "Formation mechanism and evolution processes of flood channels in the Changjiang estuary", this paper study systematically the formation and evolution, erosion and deposition, and features of dynamic sediment of flood channels in the Changjiang Estuary, and put forward a development model of the different flood channels.
Based on the data collecting from previous study results and measuring actually in the spring and neap tide during the flood season in 2001 and dry season in 2003, this paper proposes that the concept of the flood channel should include a more comprehensive implication. All negative landforms, which are shaped by flood-dominated current, such as souring hole, scouring channel and flood channel, are belong to the study area of flood channels. The character of flood channel can be determined by dominate current, dominate tidal volume, dominate sediment concentration, channel geometry configuration and direction of bed sediment transport and so on.
Influenced by flood dominated current in the flood channels, the characteristics of surface sediments, such as grain size, light and heavy minerals, micro-paleontology and magnetism in the flood channel are very different from those in the ebb channels, this kind differences is the response for complex hydrodynamic in estuary.
Changes of sediments characteristics of core A and C reflect the sediment environment varied during channel formation and development of flood channel. The open and close environment before and after the channel formation makes different sediments deposit in the flood channels. At the same time the various sediments give the important information about the surroundings difference. Although application of activity of 210Pb in determining age of sediments of estuarine and coastal environment is very difficult, it provides important information about sediment environment and hydrodynamic.
Supported by GIS, quantitative changes of erosion and deposition of the Xinqiao Channel are calculated. These results combing sediment characteristics of vertical profile illustrate the formation mechanism and evolution process. Make a comprehensive view of all study results about the flood channel, a model of formation and evolution of the flood channels was proposed. According to this model, not all flood channels formed by ebb channels divided by sand spit develop toward death, some of them may be keeping the current situation or transform to the reserve channel with the change of runoff and sediment concentration from upper reach. Although lower part of the Xinqiao Channel deposits in recent years, and upper part of the Nanxiaohong Channel is developing towards the ebb channel, they will keep developing with the flood channel features according to the model.
本文的研究工作主要包括：1．收集整理海图资料以及以前的有关实测数据；2．参加2001洪季和2003年枯季野外定点、走航观测和取样工作；3．进行大量的室内样品分析和数据处理工作，包括沙波资料的分析计算，矿物分析的样品预处理和上机测试，样品室内磁性测量，海图数值化和冲淤计算等。通过以上的研究认为河口涨潮槽的概念应该有更为广泛的含义，包括河口一切由涨潮流作用为主形成的负地形，如涨潮冲刷坑，涨潮冲刷槽和涨潮水道等，涨潮槽的特征应该保持多年。用优势流、优势沙、优势潮量、涨潮槽形态和净底沙运移方向的方法都可以表达涨潮槽的性质。
河口涨潮槽在涨潮优势流作用下，槽内表层沉积物的粒度、轻重矿物、微体古生物和磁学等特征不同于落潮槽相应的沉积特征，体现了沉积物的分布对河口复杂水动力的响应。
河口涨潮槽浅层沉积物粒度、轻重矿物、微体古生物和磁学性质的变化可说明涨潮槽在形成演化过程中沉积环境的变化。形成前沉积环境较为开敞，形成后由于沙嘴的阻隔作用使涨潮槽内环境较为封闭，因此在垂向上沉积物的性质不同。将~(210)Pb放射性测年方法应用于河口海岸环境时需慎重，虽然由于活度的变化无法准确确定垂向沉积物的沉积年代，但仍可给我们提供沉积物沉积时环境和水动力变化的信息。
用GIS方法计算1861-2002年新桥水道区域的冲淤变化，可定量表达涨潮槽在不同时间尺度形成演化规律，结合涨潮槽岩芯沉积物垂向的沉积特性变化，可阐明涨潮槽的形成机理与演化过程，并提出不同种类型涨潮槽的形成演化模式。
Study of a flood channel or flood-dominated channel of estuary is not only an important content in estuarine dynamic geomorphology and dynamic sediment, but also is a practical problem nearly related to the selection of harbor sites, regulation of sea-entering waterway, bank revetment and land reclamation, and even the comprehensive exploitation of estuaries. Supported by the State Natural Science Foundation Project "Formation mechanism and evolution processes of flood channels in the Changjiang estuary", this paper study systematically the formation and evolution, erosion and deposition, and features of dynamic sediment of flood channels in the Changjiang Estuary, and put forward a development model of the different flood channels.
Based on the data collecting from previous study results and measuring actually in the spring and neap tide during the flood season in 2001 and dry season in 2003, this paper proposes that the concept of the flood channel should include a more comprehensive implication. All negative landforms, which are shaped by flood-dominated current, such as souring hole, scouring channel and flood channel, are belong to the study area of flood channels. The character of flood channel can be determined by dominate current, dominate tidal volume, dominate sediment concentration, channel geometry configuration and direction of bed sediment transport and so on.
Influenced by flood dominated current in the flood channels, the characteristics of surface sediments, such as grain size, light and heavy minerals, micro-paleontology and magnetism in the flood channel are very different from those in the ebb channels, this kind differences is the response for complex hydrodynamic in estuary.
Changes of sediments characteristics of core A and C reflect the sediment environment varied during channel formation and development of flood channel. The open and close environment before and after the channel formation makes different sediments deposit in the flood channels. At the same time the various sediments give the important information about the surroundings difference. Although application of activity of 210Pb in determining age of sediments of estuarine and coastal environment is very difficult, it provides important information about sediment environment and hydrodynamic.
Supported by GIS, quantitative changes of erosion and deposition of the Xinqiao Channel are calculated. These results combing sediment characteristics of vertical profile illustrate the formation mechanism and evolution process. Make a comprehensive view of all study results about the flood channel, a model of formation and evolution of the flood channels was proposed. According to this model, not all flood channels formed by ebb channels divided by sand spit develop toward death, some of them may be keeping the current situation or transform to the reserve channel with the change of runoff and sediment concentration from upper reach. Although lower part of the Xinqiao Channel deposits in recent years, and upper part of the Nanxiaohong Channel is developing towards the ebb channel, they will keep developing with the flood channel features according to the model.
引文
Ariathurai R. Krone R.B., Finite element modei for cohesive sediment transport [J]. Joumal of Hydraulic Engineering, ASCE, 1976, 102(3) :323-338
Amoldo V L, Larry P.A. Spatial gradients in the flow over an estuarine channel [J]. Estuaries, 1999,22(2A): 179-193
Bartholdy J.Transport of suspended matter in a bar-built Danish estuary[J]. Estuarine, Coastal and Shelf Science, 1984,18(5) :527-541
Barua, K. Dilip. Suspended sediment monement in the estuary of the Ganges-Brahmaputra-Meghna river system[J]. Marine Geology, 1994, 91:243-253
Cole P, Miles GV. Two-dimensional model of mud transport. Joumal of Hydraulic Engineering, ASCE, 1983,109(1) : 1-12
Davies, A.G A mathematical model of sediment in suspension in a uniform reversing tidal flow. Geog. phys[J]. J. R. Astron, Sco. 1977, 51:503-529
Dyer K.R., The salt balances in stratified estuaries [J]. Estuarine and coastal marine science, 1974,2:275-281
Dyer, K.R. Lateral circulation effects in estuaries. In: Estuaries, geophysics and the environment [M] Nat. Acad. Sci., Washington, D.C, 1977,22-29
Dyer, K.R., The balance of suspended sediment in the Gironde and Thames estuaries[A], In: Edited by B.Kjerfve, Estuarine transport precesses[C]. Univ. South Carolina press,Columbia,1978,135-145
Fairbridge R.W. and J.Bourgeois(ed.), The Encyclopedia of Sedimentology vol[M]. Donden, Hutchinson and Ross, Inc. 1978,288
Fenster, M.S, D. M. FitzGerald. Morphodynamics, stiatigraphy, and sediment transport pattems of the Kennebec River estuary, Maine, USA[J]. Sedimentary Geology, 1996,107:99-120
Fishcher H.B. Mass Iransport mechanisms in partially mixed estuaries [J]. J. Fluid Mech. 1972:53:672-687
Ginsberg S. Silvia, Gerardo M.E. Perillo. Deep-holes at tidal channel junctions Bahia Blanca estuary, Argentina [J]. Marine Geology, 1999, 160:171-182
Guilcher. A. Morphologie Littorale et Sous Marine [M]. Paris Presses Univ. France, 1954,216
Green O. Mnlcolm, Robert G Bell, Tony J. Dolphin, et al. Silt and sand transport in a dep tidal channel of a large estuary (Manukar Harbour, New Zealand)[J]. Marine Geology, 2000,163:217-240
Leopold, L.B, Collins J.N., Collins L.M. Hydrology of some tidal channels in estuarine marshland near San Francisco (J). Catena, 1993,20: 469-493
Lin P., Huan J, Li X. Unsteady transport of suspended load at small concentration [J]). Joumal of Hydraulic Engineering, ASCE, 1983, 109(1) :86-98
Nicholson J. B.A. O'Connor, Cohesive sediment transport model [J]. Journal of Hydraulic Engineering, 1988, 112(7) :621-640
Onishi Y. Sediment-containment transport model [J]. Journal of Hydraulic Engineering. ASCE, 1981,107(9): 1089～1107
Perillo G.M.E, M.C. Piccolo. Importance of grid-cell area in the estimation of estuarine residual forxes [J]. Estuaries, 1998, 21(1): 14～28
Pethick. J. An introduction to coastal geomorphology [M]. Edward arnold. London, 1984
Scndators P.D. On the numerical modeling of cohesive sediment transport [J]. Journal of Hydraulic Research, 1981, 9(1):61～68
Schubel, J.R. Size distributions of the suspended particles of the Chesapeake Bay turbidity maximum [J]. Neth. J. Sea Rea 1969, 4(3):183～529
Thomas W.A, Presuhn A.L. Mathematical modeling of scour and deposition[J]. Journal of Hydraulic Engineering, ASCE, 1977, 103(8):851～863
Uncle R.J., Elliott R.C.A. Weston S.A. Dispersion of salt and suspended sediment in a partly mixed estuary [J]. Estuaries, 1985, 8:256～269
Van Rijin. Field verification of 2D and 3D suspended sediment model[J]. Journal of Hydraulic Engineering, ASCE, 1990, 116(10): 1270～1288
曹沛奎，董永发，周月琴．杭州湾北部潮流冲刷槽演变的分析[J]．地理学报，1989，44(2)：157～166
陈吉余，虞志英，陈德昌等．钱塘江河口段的泥沙移运与河槽变形[C]．河口海岸研究成果汇编(钱塘江河口研究专集)，华东师范大学河口海岸研究室，1965：43～68
陈吉余，恽才兴，徐海根等．两千年来长江河口发育模式．海洋学报，1979，1(1)：103～111
贺松林．长江河口下段分汊口的组构模式[J]．海洋学报，2000，22(1)：84～92
钱宁，张仁，周志德，河床演变学[M]．北京：科学出版社，1987：299～302
沈焕庭．长江口潮波传播及其对河槽演变的影响．中国地理学会1977年地貌学术讨论会论文集[C]．北京：科学出版社，1981：53～60
沈焕庭，李九发，金元欢．河口涨潮槽的演变及治理[J]．海洋与湖沼，1995，26(1)：83～89
宋志尧，严以新，朱勇．河口涨潮沟形成水动力机制初探[J]．河海大学学报(自然科学版)，2002，30(4)：45～48
熊绍隆，陶圭棱，卢祥兰等．杭州湾北岸深槽冲淤变化实验研究[J]．水利学报，1994，10：23～30
严以新，高进，郑金海等．长江口南港泥沙运动的水动力条件[J]．河海大学学报(自然科学版)，2002，30(5)：1-6
杨干然，罗宪林，彭炳健．新会崖门港外航道拦门沙的发育演变及治理问题，海岸动力地貌学研究及其在华南港口建设中的应用[C]．广州：中山大学出版社，1995：177～206
余祁文，符宁平．杭州湾北岸深槽形成及演化特性的研究[J]，1994，16(3)：74～85
Amoldo V L, Larry P.A. Spatial gradients in the flow over an estuarine channel [J]. Estuaries, 1999,22(2A): 179-193
Bartholdy J.Transport of suspended matter in a bar-built Danish estuary[J]. Estuarine, Coastal and Shelf Science, 1984,18(5) :527-541
Barua, K. Dilip. Suspended sediment monement in the estuary of the Ganges-Brahmaputra-Meghna river system[J]. Marine Geology, 1994, 91:243-253
Cole P, Miles GV. Two-dimensional model of mud transport. Joumal of Hydraulic Engineering, ASCE, 1983,109(1) : 1-12
Davies, A.G A mathematical model of sediment in suspension in a uniform reversing tidal flow. Geog. phys[J]. J. R. Astron, Sco. 1977, 51:503-529
Dyer K.R., The salt balances in stratified estuaries [J]. Estuarine and coastal marine science, 1974,2:275-281
Dyer, K.R. Lateral circulation effects in estuaries. In: Estuaries, geophysics and the environment [M] Nat. Acad. Sci., Washington, D.C, 1977,22-29
Dyer, K.R., The balance of suspended sediment in the Gironde and Thames estuaries[A], In: Edited by B.Kjerfve, Estuarine transport precesses[C]. Univ. South Carolina press,Columbia,1978,135-145
Fairbridge R.W. and J.Bourgeois(ed.), The Encyclopedia of Sedimentology vol[M]. Donden, Hutchinson and Ross, Inc. 1978,288
Fenster, M.S, D. M. FitzGerald. Morphodynamics, stiatigraphy, and sediment transport pattems of the Kennebec River estuary, Maine, USA[J]. Sedimentary Geology, 1996,107:99-120
Fishcher H.B. Mass Iransport mechanisms in partially mixed estuaries [J]. J. Fluid Mech. 1972:53:672-687
Ginsberg S. Silvia, Gerardo M.E. Perillo. Deep-holes at tidal channel junctions Bahia Blanca estuary, Argentina [J]. Marine Geology, 1999, 160:171-182
Guilcher. A. Morphologie Littorale et Sous Marine [M]. Paris Presses Univ. France, 1954,216
Green O. Mnlcolm, Robert G Bell, Tony J. Dolphin, et al. Silt and sand transport in a dep tidal channel of a large estuary (Manukar Harbour, New Zealand)[J]. Marine Geology, 2000,163:217-240
Leopold, L.B, Collins J.N., Collins L.M. Hydrology of some tidal channels in estuarine marshland near San Francisco (J). Catena, 1993,20: 469-493
Lin P., Huan J, Li X. Unsteady transport of suspended load at small concentration [J]). Joumal of Hydraulic Engineering, ASCE, 1983, 109(1) :86-98
Nicholson J. B.A. O'Connor, Cohesive sediment transport model [J]. Journal of Hydraulic Engineering, 1988, 112(7) :621-640
Onishi Y. Sediment-containment transport model [J]. Journal of Hydraulic Engineering. ASCE, 1981,107(9): 1089～1107
Perillo G.M.E, M.C. Piccolo. Importance of grid-cell area in the estimation of estuarine residual forxes [J]. Estuaries, 1998, 21(1): 14～28
Pethick. J. An introduction to coastal geomorphology [M]. Edward arnold. London, 1984
Scndators P.D. On the numerical modeling of cohesive sediment transport [J]. Journal of Hydraulic Research, 1981, 9(1):61～68
Schubel, J.R. Size distributions of the suspended particles of the Chesapeake Bay turbidity maximum [J]. Neth. J. Sea Rea 1969, 4(3):183～529
Thomas W.A, Presuhn A.L. Mathematical modeling of scour and deposition[J]. Journal of Hydraulic Engineering, ASCE, 1977, 103(8):851～863
Uncle R.J., Elliott R.C.A. Weston S.A. Dispersion of salt and suspended sediment in a partly mixed estuary [J]. Estuaries, 1985, 8:256～269
Van Rijin. Field verification of 2D and 3D suspended sediment model[J]. Journal of Hydraulic Engineering, ASCE, 1990, 116(10): 1270～1288
曹沛奎，董永发，周月琴．杭州湾北部潮流冲刷槽演变的分析[J]．地理学报，1989，44(2)：157～166
陈吉余，虞志英，陈德昌等．钱塘江河口段的泥沙移运与河槽变形[C]．河口海岸研究成果汇编(钱塘江河口研究专集)，华东师范大学河口海岸研究室，1965：43～68
陈吉余，恽才兴，徐海根等．两千年来长江河口发育模式．海洋学报，1979，1(1)：103～111
贺松林．长江河口下段分汊口的组构模式[J]．海洋学报，2000，22(1)：84～92
钱宁，张仁，周志德，河床演变学[M]．北京：科学出版社，1987：299～302
沈焕庭．长江口潮波传播及其对河槽演变的影响．中国地理学会1977年地貌学术讨论会论文集[C]．北京：科学出版社，1981：53～60
沈焕庭，李九发，金元欢．河口涨潮槽的演变及治理[J]．海洋与湖沼，1995，26(1)：83～89
宋志尧，严以新，朱勇．河口涨潮沟形成水动力机制初探[J]．河海大学学报(自然科学版)，2002，30(4)：45～48
熊绍隆，陶圭棱，卢祥兰等．杭州湾北岸深槽冲淤变化实验研究[J]．水利学报，1994，10：23～30
严以新，高进，郑金海等．长江口南港泥沙运动的水动力条件[J]．河海大学学报(自然科学版)，2002，30(5)：1-6
杨干然，罗宪林，彭炳健．新会崖门港外航道拦门沙的发育演变及治理问题，海岸动力地貌学研究及其在华南港口建设中的应用[C]．广州：中山大学出版社，1995：177～206
余祁文，符宁平．杭州湾北岸深槽形成及演化特性的研究[J]，1994，16(3)：74～85