沉积物输运对砂质海底稳定性影响的评估方法及应用实例
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摘要
<正> 海底沉积物运动可由重力作用引起,它常以水下滑坡的形式出现,对高含水量的细颗粒物质尤其是如此(林振宏等,1990);在陆架和陆坡区,水下滑坡可由于地震等事件而诱发。此外,海底稳定性还与水流作用引起的沉积物运动有关,沉积物输运造成相应的堆积和冲刷,从而改变海底的形态。在许多环境中,沉积物输运是控制海底稳定性的主要因素。海底某处高程在一定时段内的变化系由活动层厚度、冲淤量和底部地貌形
Sediment movement patterns control the stability of sandy seabed in three aspects: (i) the sediment erodibility time and the thickness of the moving layer; (ii) seabed accretion/erosion and their rate; and (iii) seabed elevation changes in response to bedform (e.g.underwater dunes and tidal ridges) migration. These problems can be solved by the following procedures. Firstly, the sediment erodibility time and the rate of bed-load transport are calculated using an appropriate equation which takes into account the combined effect of waves and tidal currents. Secondly, the moving layer thickness and the accretion/ erosion rate are estimated using the transport rate data. Finally, the information on the migration velocity of dunes/ridges and the resultant seabed elevation changes is obtained using the transport data and the geomorphic data of the bedform. As an example for its usage, we applied the method to the assessment of seabed stability over an area to the west of Hainan Island. The results show that the seabed material is highly mobile, with active sediment movement. The rate and amplitude of seabed elevation changes are both relatively large, in response to rapid bedform migration. These characteristics must be taken into account in the development of the natural resources of the region.
Sediment movement patterns control the stability of sandy seabed in three aspects: (i) the sediment erodibility time and the thickness of the moving layer; (ii) seabed accretion/erosion and their rate; and (iii) seabed elevation changes in response to bedform (e.g.underwater dunes and tidal ridges) migration. These problems can be solved by the following procedures. Firstly, the sediment erodibility time and the rate of bed-load transport are calculated using an appropriate equation which takes into account the combined effect of waves and tidal currents. Secondly, the moving layer thickness and the accretion/ erosion rate are estimated using the transport rate data. Finally, the information on the migration velocity of dunes/ridges and the resultant seabed elevation changes is obtained using the transport data and the geomorphic data of the bedform. As an example for its usage, we applied the method to the assessment of seabed stability over an area to the west of Hainan Island. The results show that the seabed material is highly mobile, with active sediment movement. The rate and amplitude of seabed elevation changes are both relatively large, in response to rapid bedform migration. These characteristics must be taken into account in the development of the natural resources of the region.
引文
于克俊等,1995,北部湾台风风海流三维数值后报,海洋科学集刊,36:55-64。
方国洪、于克俊,1998,斜压海洋动力学的一种三维数值模式Ⅰ.动力学方程数值格式,海洋与湖沼,29(3) :232-239。
王文质,1981,北部湾寒潮风浪谱的初步分析,南海海洋科学集刊,2:79-92。
王颖、蔡明理,1996,中国海洋地理,科学出版社(北京),15-58。
朱耀华、方国洪,1993,一种二维和三维嵌套海洋流体动力学数值模式及其在北部湾潮汐和潮流数值模拟中的应用,海洋与湖沼,24(2) :117-125。
苏纪兰等,1996,中国海洋地理,科学出版社(北京),93-129。
林振宏、杨作升(主编),1990,海岸河口区重力再沉积和底坡的不稳定性,海洋出版社(北京),137。
Allen, J. R. L., 1982, Sedimentary Structures: Their Character and Physical Basis (Vol. 1 ), Elsevier, New York, 593．
Amos, C. L. and E. L. King, 1984, Sand waves and sand ridges of the Canadian eastern seabed: a comparison to global occurrences, Marine Geology ,57 : 167-208．
Ashley, G. M., C. Boothroyd, J. S. Bridge et al., 1990, Classification of large-scale subaqeous bedforms: a new look at an old problem, Journal of Sedimentary Petrology ,60:160-172．
Bagnold, R. A., 1966, An approach to the sediment transport problem from general physics, U. S. Geological Survey Professional Paper, 422-Ⅰ, 1-37．
Cacchione, D. A. and D. E. Drake, 1990, Shelf sediment transport: an overview with applications to the northern California continental shelf. In: Le Mehaute, B. and Hanes, D.M. (editors), The Sea( Vol. 9: Ocean Engineering Science), John Wiley, New York, 775-813．
Collins, M.B. , S.J. Shimwell, S. Gao et al. , 1995, Water and sediment moveanent in the vicinity of linear sandbanks : the Norfolk Banks, southern North Sea, Marine Ceology,123:125-142．
Dyer, K. R., 1986, Coastal and Estuarine Sediment Dynamics, John Wiley, Chichester, 324．
Flemming, B. W., 1988, Zur Klassification subauatischer, stromungstrans versaler transportkorper, Boch. Geol. und Geotechn. Arb . , 29:44-47．
Gadd, P. E., J. W. Lavelle and D. J. P. Swift, 1978, Estimates of sand transport on the New York sheff using near-bottom current meter obsorvations, Journal of Sedimentary Petrology, 48 : 239-252．
Gao, S. and M.B. Collins, 1997, Changes in sediment transport directions caused by wave action and tidal flow time-asymmetry, Journal of Coastal Research, 13:198-201．
Hardisty, J., 1983, An assessment and calibration of formulations of Bagnold's bedload equation, Journal of Sedimentary Petrology, 53 : 1007-1010．
Harris, C. K. and P. L. Wiberg, 1997, Approaches to quantifying long-term continental shelf sediment transport with an exsample from the Northern California STRESS mid-shelf site, Continental Shelf Research, 17:1389-1418．
Harris, P.T. and M. B. Collins, 1988, Estimation of annual bedload flux in a macrotidal estuary: Bristol Channel, UK, Marine Geology, 83 : 237-252．
Hawkins, A. B. and M. J. Sebbage, 1972 ,The reversal of sand waves in the Bristol Channel, Marine Geology, 12: M7-M9．
Hulscher, S. J., H. E. de Swart and H. J. de Vriend, 1993, The generation of offshore tidal sand banks and sand waves, Contniental Shelf Research, 13 : 1183-1204．
Huthnance, J. , 1982a, On one mechanism forming linear sand banks, Estuarine, Coastal and Shelf Science, 14:79-99．
Huthnance, J., 1982b, On the formation of sand banks of finite extent, Estuarine, Coastal and Shelf Science, 15:277-299．
Liu,Z.-X. ,1997,Yangtze Shoal-a modern tidal sand sheet in the northwestern part of the East China Sea, Marine Geology, 137: 321-330．
Madsen,O, S. and W. D. Grant, 1975, Quantitative description of sediment transport by waves, Proceedings of the 15th Coastal Engineering Conference , 1093-1112．
Miller, M.C., I. N. McCave and P. D. Komar, 1977, Threshold of sediment motion under unidirectional currents, Sedimentology, 24: 507-527．
Muir Wood, A. M. and C. A. Fleming, 1981, Coastal hydraulics (2nd edition ), Macmillan, London,280．
Rubin, D. M. and R. E. Hunter, 1982, Bedform climbing in theory and nature, Sedimentology, 29:121-138．
Stride, A. H. ( editor), 1982, Offshore Tidal Sands, Processes and Deposits, Chapman and Hall, 222．
Vincent, C. E., R.A. Young and D. J. P. Swift, 1983, Sediment transport on the Long Island shoreface, North American Atlantic shelf: role of waves and currents in shoreface maintenance, Continental Shelf Research ,2,163-181．
Wang, Y. P. and Gao, S. ,2001, Modification to the Hardisty Equation, regarding the relationship between sediment transport rate and particle size. Journal of Sedimentary Research,78,118-121．
方国洪、于克俊,1998,斜压海洋动力学的一种三维数值模式Ⅰ.动力学方程数值格式,海洋与湖沼,29(3) :232-239。
王文质,1981,北部湾寒潮风浪谱的初步分析,南海海洋科学集刊,2:79-92。
王颖、蔡明理,1996,中国海洋地理,科学出版社(北京),15-58。
朱耀华、方国洪,1993,一种二维和三维嵌套海洋流体动力学数值模式及其在北部湾潮汐和潮流数值模拟中的应用,海洋与湖沼,24(2) :117-125。
苏纪兰等,1996,中国海洋地理,科学出版社(北京),93-129。
林振宏、杨作升(主编),1990,海岸河口区重力再沉积和底坡的不稳定性,海洋出版社(北京),137。
Allen, J. R. L., 1982, Sedimentary Structures: Their Character and Physical Basis (Vol. 1 ), Elsevier, New York, 593．
Amos, C. L. and E. L. King, 1984, Sand waves and sand ridges of the Canadian eastern seabed: a comparison to global occurrences, Marine Geology ,57 : 167-208．
Ashley, G. M., C. Boothroyd, J. S. Bridge et al., 1990, Classification of large-scale subaqeous bedforms: a new look at an old problem, Journal of Sedimentary Petrology ,60:160-172．
Bagnold, R. A., 1966, An approach to the sediment transport problem from general physics, U. S. Geological Survey Professional Paper, 422-Ⅰ, 1-37．
Cacchione, D. A. and D. E. Drake, 1990, Shelf sediment transport: an overview with applications to the northern California continental shelf. In: Le Mehaute, B. and Hanes, D.M. (editors), The Sea( Vol. 9: Ocean Engineering Science), John Wiley, New York, 775-813．
Collins, M.B. , S.J. Shimwell, S. Gao et al. , 1995, Water and sediment moveanent in the vicinity of linear sandbanks : the Norfolk Banks, southern North Sea, Marine Ceology,123:125-142．
Dyer, K. R., 1986, Coastal and Estuarine Sediment Dynamics, John Wiley, Chichester, 324．
Flemming, B. W., 1988, Zur Klassification subauatischer, stromungstrans versaler transportkorper, Boch. Geol. und Geotechn. Arb . , 29:44-47．
Gadd, P. E., J. W. Lavelle and D. J. P. Swift, 1978, Estimates of sand transport on the New York sheff using near-bottom current meter obsorvations, Journal of Sedimentary Petrology, 48 : 239-252．
Gao, S. and M.B. Collins, 1997, Changes in sediment transport directions caused by wave action and tidal flow time-asymmetry, Journal of Coastal Research, 13:198-201．
Hardisty, J., 1983, An assessment and calibration of formulations of Bagnold's bedload equation, Journal of Sedimentary Petrology, 53 : 1007-1010．
Harris, C. K. and P. L. Wiberg, 1997, Approaches to quantifying long-term continental shelf sediment transport with an exsample from the Northern California STRESS mid-shelf site, Continental Shelf Research, 17:1389-1418．
Harris, P.T. and M. B. Collins, 1988, Estimation of annual bedload flux in a macrotidal estuary: Bristol Channel, UK, Marine Geology, 83 : 237-252．
Hawkins, A. B. and M. J. Sebbage, 1972 ,The reversal of sand waves in the Bristol Channel, Marine Geology, 12: M7-M9．
Hulscher, S. J., H. E. de Swart and H. J. de Vriend, 1993, The generation of offshore tidal sand banks and sand waves, Contniental Shelf Research, 13 : 1183-1204．
Huthnance, J. , 1982a, On one mechanism forming linear sand banks, Estuarine, Coastal and Shelf Science, 14:79-99．
Huthnance, J., 1982b, On the formation of sand banks of finite extent, Estuarine, Coastal and Shelf Science, 15:277-299．
Liu,Z.-X. ,1997,Yangtze Shoal-a modern tidal sand sheet in the northwestern part of the East China Sea, Marine Geology, 137: 321-330．
Madsen,O, S. and W. D. Grant, 1975, Quantitative description of sediment transport by waves, Proceedings of the 15th Coastal Engineering Conference , 1093-1112．
Miller, M.C., I. N. McCave and P. D. Komar, 1977, Threshold of sediment motion under unidirectional currents, Sedimentology, 24: 507-527．
Muir Wood, A. M. and C. A. Fleming, 1981, Coastal hydraulics (2nd edition ), Macmillan, London,280．
Rubin, D. M. and R. E. Hunter, 1982, Bedform climbing in theory and nature, Sedimentology, 29:121-138．
Stride, A. H. ( editor), 1982, Offshore Tidal Sands, Processes and Deposits, Chapman and Hall, 222．
Vincent, C. E., R.A. Young and D. J. P. Swift, 1983, Sediment transport on the Long Island shoreface, North American Atlantic shelf: role of waves and currents in shoreface maintenance, Continental Shelf Research ,2,163-181．
Wang, Y. P. and Gao, S. ,2001, Modification to the Hardisty Equation, regarding the relationship between sediment transport rate and particle size. Journal of Sedimentary Research,78,118-121．
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