摘要
在长江河口北槽抛泥过程中 ,应用ASSM Ⅰ型声学悬浮泥沙观测系统观测悬沙浓度的时空分布规律 ,结合多普勒流速剖面仪走航式断面流速测量。研究发现 :( 1 )泥沙浓度垂向分布形成至少三种结构类型 ,即上小下大的“L”型和指数型 ,上大下小的“漂浮”型 ;( 2 )受抛泥泥沙输移的影响 ,断面流场形成低流速区 ,或分布在水体表、中层 ,或贯穿整个水体 ,形成流速切变锋 ,它们的强度随抛泥泥沙输移扩散逐渐减弱 ;( 3)在落潮流和颗粒重力共同作用下 ,抛泥泥沙同时存在输移扩散和沉降过程。小潮型抛泥泥沙主要就近扩散和沉降 。
ASSM Ⅰ Acoustics Concentration Profiler and Acoustic Doppler Current Profiler were applied to simultaneously observe suspended sediment concentrations (SSCs) and currents during dredged sediment disposal in the Changjiang (Yangtze) Estuary. In situ observations show that (a) at least three types of vertical SSC profiles are found, i.e., L type and exponent type with upper layer concentrations being smaller, and floating type with upper layer concentrations being higher; (b) due to the effect of dredged sediment disposal on the flow, low velocity zones occur in the upper parts or the whole water column and, for the latter case, vertical flow shear fronts are formed and they become gradually weaker with the diffusion and settling of the disposal sediment; (c) both sediment transport diffusion and settling coexist during the disposal of dredged sediment, under the combined action of ebb current and gravity. Disposed sediment is deposited dominantly near the disposal site on neaps, and it disperses far away in moderate and spring tides.
出处
《海洋与湖沼》
CAS
CSCD
北大核心
2003年第1期83-93,共11页
Oceanologia Et Limnologia Sinica
基金
上海市博士后科研资助项目 沪科 2 0 0 1第 5 3 5号
同济大学海洋地质重点实验室开放课题
华东师范大学河口海岸国家重点实验室开放课题资助 2 0 0 2 1 0号
关键词
长江河口
扩散过程
悬沙
抛泥
声学后散射观测
沉降
Suspended Sediment, Sediment Disposal, Acoustic Backscatter Observation, Changjiang River estuary
