摘要
对在杭州湾深水航道上的站点处观测到的水文泥沙数据进行分析,并绘制出水流?悬沙浓度随时间?空间变化的等值线图以及各层观测的水流流速?流向随时间过程图?得出了该处的水流?悬沙浓度随时间?空间变化的规律: 流速基本上是随涨急?落急达到最大值,随涨憩?落憩达到最小值?流向随时间变化较大?悬沙浓度一般是在涨急?涨憩和落急附近达到最大值并在底层形成高含沙区,即有浮泥产生?即使是处于小潮,杭州湾依然有浮泥产生?利用一个悬浮泥沙声学观测仪,在杭州湾深水航道东挖槽小潮时, 对底部泥沙浓度进行了实验观测?结果发现底部泥沙存在分层结构:从上往下分别是低浓度悬沙层?高浓度悬沙层和浮泥层?声学图像显示有四种不同频率的界面波:Ⅰ.介于低浓度悬沙层和高浓度悬沙层之间的低频界面波;Ⅱ. 介于高浓度悬沙层和可移动浮沙层之间的低频内波;Ⅲ. 介于可移动浮沙层和固定浮泥层之间的波, 被谨慎地解释为低频界面波;Ⅳ. 在固定浮泥层上产生的是高频界面波?这些界面波起到次级的动力作用,增强了局部粘性泥沙的再悬浮和再挟运?
Tidal current velocity and suspended sediment concentration have been measured at seven monitoring stations in the Hangzhou Bay. Two types of plots have been obtained: 1) time series of current velocity and suspended sediment concentration (contour lines); 2) time series of current speed and direction measured at six different depths. Those data are used to examine the mechanisms for the formation of the fluid mud in the Hangzhou Bay. By using an acoustic suspended sediment monitor, layered structures are found in a proposed navigational channel at neap tide in the Hangzhou Bay: downwards these are low concentration suspension; high concentration suspension; and fluid mud. Acoustic images reveale four different frequencies of interfacial waves. Type Ⅰ is a low-frequency interfacial wave between the low concentration suspension and the high concentration suspension. Type Ⅱ is a low-frequency internal wave between the high concentration suspension and the mobile fluid mud. Type Ⅲ is cautiously interpreted as a low-frequency interfacial wave between the mobile fluid mud and the stationary fluid mud, on which are superimposed the Type Ⅳ high-frequency interfacial wave. These interfacial waves act as the secondary dynamic forcing, which enhances local cohesive sediment resuspension and re-entrainment.
出处
《海洋通报》
CAS
CSCD
北大核心
2001年第6期40-50,共11页
Marine Science Bulletin
基金
国家教育部跨世纪优秀人才培养计划基金[教科函(1992)2号]
上海市青年科技启明星计划基金(94QA14005)资助项目
关键词
杭州湾
深水航道
界面波
浮泥
泥沙
悬沙
deep-water navigational channel
fluid mud
interfacial wave
Hangzhou Bay
