长江口北港上段河道枯季悬沙浓度垂向分布特征研究
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摘要
基于2018年4月15日至4月24日在长江口北港主槽大小潮连续10天的定点水文泥沙观测资料,对枯季期间北港上段河道悬沙浓度的垂线分布特征进行了研究。结果表明:研究区域的悬沙浓度较低,大小潮平均值仅为0.17 kg/m~3,悬沙浓度具有大潮显著高于小潮,涨落潮平均浓度接近的特点;水动力则具有大潮明显强于小潮、落潮明显强于涨潮的特点;观测期间的盐度值很低,平均值仅为0.16 psu,盐度的大小潮变化、涨落潮变化以及垂向变化都非常小,盐度密度分层对悬沙剖面影响微弱。在这种动力、泥沙和盐度环境下,大潮期间的悬沙剖面主要为斜线型和指数型;小潮期间的悬沙剖面有斜线型、垂线型和指数型,其中以斜线型占主导。通过Rouse公式拟合发现,大部分的实测悬沙剖面较符合Rouse公式,根据该公式计算得到的悬沙沉降速度介于0.36～2.89 mm/s。Soulsby公式能够对实测的斜线型和垂线型悬沙剖面进行较准确预测,平均误差控制在10%以内。
Based on the field observation data of current velocity and suspended sediment concentration(SSC) measured in the upper reach of North Channel in the Changjiang Estuary from 15~(th) April to 24~(th) April in 2018, the vertical distribution patterns of SSC during the neap and spring tides are studied. The results show the SSCs in the study area were relatively low, with the mean value of only 0.17 kg/m~3. SSCs were higher in spring tide than in neap tide, and close to each other for the flood-mean and ebb-mean values. Tidal currents were much stronger in spring tide than in neap tide, and in ebb phase than in flood phase. Salinity was considerable low during the survey period, with the mean value of only 0.16 psu. The neap-spring variation, flood-ebb variation and vertical variation of salinity were all very small, indicating the impact of salinity-induced stratification on the SSC profile is negligible. In such hydrodynamics, sediment dynamics and salinity condition, the SSCs profiles during the spring tide were the linear type and exponential type. But during the neap tide the SSCs profiles were the linear type, vertical-line type and exponential type, and the linear profile was the dominant type. By fitting Rouse equation, we found that most of measured SSCs profiles fitted Rouse equation roughly, and the settling velocity of suspended sediment deduced by this equation is between 0.36-2.89 mm/s.Soulsby equation can accurately predict the observed linear and vertical-line types of SSC profiles, with the average error less than 10%.
Based on the field observation data of current velocity and suspended sediment concentration(SSC) measured in the upper reach of North Channel in the Changjiang Estuary from 15~(th) April to 24~(th) April in 2018, the vertical distribution patterns of SSC during the neap and spring tides are studied. The results show the SSCs in the study area were relatively low, with the mean value of only 0.17 kg/m~3. SSCs were higher in spring tide than in neap tide, and close to each other for the flood-mean and ebb-mean values. Tidal currents were much stronger in spring tide than in neap tide, and in ebb phase than in flood phase. Salinity was considerable low during the survey period, with the mean value of only 0.16 psu. The neap-spring variation, flood-ebb variation and vertical variation of salinity were all very small, indicating the impact of salinity-induced stratification on the SSC profile is negligible. In such hydrodynamics, sediment dynamics and salinity condition, the SSCs profiles during the spring tide were the linear type and exponential type. But during the neap tide the SSCs profiles were the linear type, vertical-line type and exponential type, and the linear profile was the dominant type. By fitting Rouse equation, we found that most of measured SSCs profiles fitted Rouse equation roughly, and the settling velocity of suspended sediment deduced by this equation is between 0.36-2.89 mm/s.Soulsby equation can accurately predict the observed linear and vertical-line types of SSC profiles, with the average error less than 10%.
引文
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[15] 茅志昌,沈焕庭,陈景山.长江口北支进入南支净盐通量的观测与计算[J].海洋与湖沼,2004,35(1):30-34.MAO Z C,SHEN H T,CHEN J S.Measurement and calculation of net salt fluxes from the North Branch into South Branch in the Changjiang River Estuary[J].Oceanologia et Limnologia Sinica,2004,35(1):30-34.
[16] 张庆河,王殿志,吴永胜,等.粘性泥沙絮凝现象研究述评(1):絮凝机理与絮团特性[J].海洋通报,2001,20(6):80-90.ZHANG Q H,WANG D Z,WU Y S,et al.A review on aggregation phenomena for cohesive sediment ( I ):mechanism for aggregation and properties of flocs[J].Marine Science Bulletin,2001,20(6):80-90.
[17] 李远,李占海,张钊,等.长江口北槽下游河道悬沙浓度垂向分布特征研究[J].华东师范大学学报(自然科学版),2017(6):114-125.LI Y,LI Z H,ZHANG Z,et al.Vertical distribution patterns of suspended sediment concentration in the North Passage of the Changjiang Estuary[J].Journal of East China Normal University(Natural Science),2017(6):114-125.
[18] 刘建华.长江口门附近海域悬沙时空变化和输运研究[D].上海:华东师范大学,2014.LIU J H.The study of the temporal and spatial variation and transport of suspended sediment in nearshore water area of Yangtze Estuary[D].Shanghai:Doctor Dissertation of East China Normal University,2014.
[19] 李九发,时伟荣.长江河口最大浑浊带的泥沙特性和输移规律[J].地理研究,1994,13(1):51-59.LI J F,SHI W R.Sediment properties and transportation in the turbidity maximum in Changjiang Estuary[J].Geographical Research,1994,13(1):51-59.
[20] 时钟.长江口北槽细颗粒悬沙絮凝体的沉降速率的近似估算[J].海洋通报,2004,23(5):51-58.SHI Z.Approximate estimations of settling velocities of fine suspended mud flocs at the North Passage of the Chanjiang Estuary[J].Marine Science Bulletin,2004,23(5):51-58.
[21] 时钟,朱文蔚,周洪强.长江口北槽口外细颗粒悬沙沉降速度[J].上海交通大学学报,2000,34(1):18-23.SHI Z,ZHU W W,ZHOU H Q.Settling velocity of fine suspended sediment in the Changjiang Estuary[J].Journal of Shanghai Jiaotong University,2000,34(1):18-23.
[22] 陈沈良,谷国传,张国安.长江口南汇近岸水域悬沙沉速估算[J].泥沙研究,2003(6):45-51.CHEN S L,GU G C,ZHANG G A.Settling velocity of suspended sediment in the Nanhui nearshore waters of Changjiang Estuary[J].Journal of Sediment Research,2003(6):45-51.
[23] WHITEHOUSE R,SOULSBY R,ROBERTS W,et al.Dynamic of esturine muds:A manual for practical applications[M].Landon Thomas Telford,2000:75-101.
[2] 蒋陈娟,李九发,吴华林,等.长江河口北槽水沙过程对航道整治工程的响应[J].海洋学报,2013(4):129-141.JIANG C J,LI J F,WU H L,et al.Effects of the deep waterway project on the characteristics of hydrodynamics and sediment dynamics in the North Passage of the Changjiang Estuary[J].Acta Oceanologica Sinica,2013(4):129-141.
[3] 姚弘毅,李九发,戴志军,等.长江河口北港河道泥沙特性及河床沙再悬浮研究[J].泥沙研究,2013(3):6-13.YAO H Y,LI J F,DAI Z J,et al.Sediment character and bed load resuspension in North Channel of Changjiang Estuary[J].Journal of Sediment Research,2013(3):6-13.
[4] LI X,ZHU J,YUAN R,et al.Sediment trapping in the Changjiang Estuary:Observations in the North Passage over a spring-neap tidal cycle[J].Estuarine,Coastal and Shelf Science,2016,177:8-19.
[5] 吴华林,沈焕庭,茅志昌.长江口南北港泥沙冲淤定量分析及河道演变[J].泥沙研究,2004(3):75-80.WU H L,SHEN H T,MAO Z C.Calculation of the amount of siltation and erosion in the South and North Channel in the Changjiang Estuary and its evolution[J].Journal of Sediment Research,2004(3):75-80.
[6] 杨忠勇,王钟,程和琴,等.基于解析解的长江口南港悬沙侧向捕集特征分析[J].海洋学报,2017(5):22-32.YANG Z Y,WANG Z,CHEN H Q,et al.Analytical study of the sediment transport in the South Channel of Yangtze Estuary,China[J].Acta Oceanologica Sinica,2017(5):22-32.
[7] 鲍道阳,朱建荣.近60年来长江河口河势变化及其对水动力和盐水入侵的影响Ⅲ.盐水入侵[J].海洋学报,2017(4):1-15.BAO D Y,ZHU J R.The effects of river regime changes in the Changjiang Estuary on hydrodynamics and salinity intrusion in the past 60 years Ⅲ.Saltwater intrusion[J].Acta Oceanologica Sinica,2017(4):1-15.
[8] 杨正东,朱建荣,王彪,等.长江河口潮位站潮汐特征分析[J].华东师范大学学报(自然科学版),2012(3):111-119.YANG Z D,ZHU J R,WANG B,et al.Analysis of tidal characteristics of the tide gauges in the Changjiang Estuary[J].Journal of East China Normal University(Natural Science),2012(3):111-119.
[9] 李一鸣.近三十年来长江口河槽沉积特征及其影响因子研究[D].上海:华东师范大学,2018.LI Y M.Studies on sediment characteristics and the influencing factors in the Yangtze Estuary riverbed during the recent 30 years[D].Shanghai:Master Dissertation of East China Normal University,2018.
[10] ROUSE H.Modern conceptions of the mechanics of turbulence[J].Trans Asce.1937,102(3):1-4.
[11] 匡翠萍.长江口拦门沙冲淤及悬沙沉降规律研究和水流盐度泥沙数学模型[D].南京:南京水利科学研究院,1993.KUANG C P.Yangtze Estuary sand erosion and deposition of suspended sediment settlement law studies and water salinity sediment mathematical model[D].Nanjing:Doctor Dissertation of Nanjing Hydraulic Research Institute,1993.
[12] RIJN L C V.Principles of sediment transport in rivers,estuaries and coastal seas[J].Morfologie Morf,1993.
[13] DYER K R.Coastal and Estuarine Sediment Dynamics[J].John Wiley & Sons Inc,1986(1):173.
[14] PRANDLE D.On salinity regimes and the vertical structure of residual flows in narrow tidal estuaries[J].Estuarine Coastal & Shelf Science,1985,20(5):615-635.
[15] 茅志昌,沈焕庭,陈景山.长江口北支进入南支净盐通量的观测与计算[J].海洋与湖沼,2004,35(1):30-34.MAO Z C,SHEN H T,CHEN J S.Measurement and calculation of net salt fluxes from the North Branch into South Branch in the Changjiang River Estuary[J].Oceanologia et Limnologia Sinica,2004,35(1):30-34.
[16] 张庆河,王殿志,吴永胜,等.粘性泥沙絮凝现象研究述评(1):絮凝机理与絮团特性[J].海洋通报,2001,20(6):80-90.ZHANG Q H,WANG D Z,WU Y S,et al.A review on aggregation phenomena for cohesive sediment ( I ):mechanism for aggregation and properties of flocs[J].Marine Science Bulletin,2001,20(6):80-90.
[17] 李远,李占海,张钊,等.长江口北槽下游河道悬沙浓度垂向分布特征研究[J].华东师范大学学报(自然科学版),2017(6):114-125.LI Y,LI Z H,ZHANG Z,et al.Vertical distribution patterns of suspended sediment concentration in the North Passage of the Changjiang Estuary[J].Journal of East China Normal University(Natural Science),2017(6):114-125.
[18] 刘建华.长江口门附近海域悬沙时空变化和输运研究[D].上海:华东师范大学,2014.LIU J H.The study of the temporal and spatial variation and transport of suspended sediment in nearshore water area of Yangtze Estuary[D].Shanghai:Doctor Dissertation of East China Normal University,2014.
[19] 李九发,时伟荣.长江河口最大浑浊带的泥沙特性和输移规律[J].地理研究,1994,13(1):51-59.LI J F,SHI W R.Sediment properties and transportation in the turbidity maximum in Changjiang Estuary[J].Geographical Research,1994,13(1):51-59.
[20] 时钟.长江口北槽细颗粒悬沙絮凝体的沉降速率的近似估算[J].海洋通报,2004,23(5):51-58.SHI Z.Approximate estimations of settling velocities of fine suspended mud flocs at the North Passage of the Chanjiang Estuary[J].Marine Science Bulletin,2004,23(5):51-58.
[21] 时钟,朱文蔚,周洪强.长江口北槽口外细颗粒悬沙沉降速度[J].上海交通大学学报,2000,34(1):18-23.SHI Z,ZHU W W,ZHOU H Q.Settling velocity of fine suspended sediment in the Changjiang Estuary[J].Journal of Shanghai Jiaotong University,2000,34(1):18-23.
[22] 陈沈良,谷国传,张国安.长江口南汇近岸水域悬沙沉速估算[J].泥沙研究,2003(6):45-51.CHEN S L,GU G C,ZHANG G A.Settling velocity of suspended sediment in the Nanhui nearshore waters of Changjiang Estuary[J].Journal of Sediment Research,2003(6):45-51.
[23] WHITEHOUSE R,SOULSBY R,ROBERTS W,et al.Dynamic of esturine muds:A manual for practical applications[M].Landon Thomas Telford,2000:75-101.
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