磨刀门水道枯季大潮水体层化混合分析  

Analysis of stratification-mixing mechanism during spring tide of dry season in the Modaomen waterway

作　　者：童朝锋[1] 李磊 孟艳秋[1] 王波[1] TONG Chaofeng;LI Lei;MENG Yanqiu;WANG Bo(College of Harbor, Coastal and Offshore Engineering, Hohai University, Nanjing 210098, China)

机构地区：[1]河海大学港口海岸与近海工程学院,江苏南京210098

出　　处：《水利水运工程学报》2018年第1期48-57,共10页Hydro-Science and Engineering

基　　金：国家自然科学基金重点资助项目(51339005);国家自然科学基金青年基金资助项目(51409094)

摘　　要：通过分析磨刀门水道枯季大潮期间的水体盐度实测资料,得出涨落潮时期盐跃层上下流速结构的差异性,确定了磨刀门水道盐度和盐水楔变化特征,判定磨刀门河口属于部分混合型河口。采用整体Richardson数、梯度Richardson数以及势能函数φ等3种层化指标,计算分析了磨刀门水道枯季大潮期垂向各层不同密度水体层化混合的周期性变化过程,指出出现层化混合的峰值时期。采用Simpson势能理论,分析了磨刀门水道枯季大潮期的河口环流、潮汐应变和潮汐紊动过程,及其与水体层化指标特征峰值的对应关系,结果显示磨刀门水道枯季大潮期河口环流加剧水体层化,潮汐紊动促进水体混合,潮汐应变则是在涨潮时促进混合,在落潮时促进层化。分析指出潮汐应变是引起磨刀门水道各层不同密度水体周期性层化混合现象的主控因子。By analyzing the measured data of hydrology and salinity during the spring tide of the dry season in the Modaomen waterway,the differences of the upper and lower velocity structure near the halocline during flood and ebb are demonstrated,the characteristics of change of salinity and salt water wedge are determined,and the Modaomen estuary is classified as a partially mixed estuary.Three stratification indexes including the overall Richardson number,gradient Richardson number and potential energy are calculated to analyze the periodic stratification-mixing process of vertical water layers with different densities,and the stratification-mixing peak time is pointed out.The Simpson potential energy theory is applied to study the processes of estuarine circulation,tidal straining and tidal stirring in the Modaomen waterway.It is revealed that there are corresponding relationships between the above three processes and the peak values of the stratification indexes.The results imply that during the spring tide of the dry season,estuarine circulation promotes stratification while tidal stirring plays the opposite role.Tidal straining suppresses stratification during flood,and during ebb it induces stratification.The tidal straining isthe main control factor of the periodic stratification-mixing process of different density water layesin the Modaomen waterway.

关 键 词：混合型河口 层化混合 河口环流 潮汐应变 潮汐紊动 

分 类 号：TV143[水利工程—水力学及河流动力学]