Lateral variability of subtidal flow at the mid‐reaches of a macrotidal estuary
Lateral variability of subtidal flow at the mid‐reaches of a macrotidal estuary
复制标题
大潮汐河口中游潮下流横向变化
DOI：
10.1002/2016jc012504
复制
发表时间：
2017
影响因子：
--
通讯作者：
N. Huybrechts
中科院分区：
文献类型：
--
作者：
Lauren Ross;A. Valle‐Levinson;A. Sottolichio;N. Huybrechts
Transverse variations of tidal and subtidal flow were investigated in a macrotidal and convergent estuary. This was accomplished by combining data analysis of current velocities and water density with numerical modeling at the mid-reaches of the Gironde Estuary (France). Nonlinear mechanisms responsible for overtide generation and hence subtidal flows were found to vary across the estuary and from neap to spring tides. Subtidal flows were driven by a combination of internal asymmetry, tidal advective accelerations, nonlinear effects of water level variations, quadratic friction, and river discharge. The quarter-diurnal overtide band (D4) in the flow was generated by internal asymmetry and tidal advective accelerations during neap tide. The ratio of quarter-diurnal to squared semidiurnal bands (D4/D22) was largest (>0.3) in sections of the channel showing subtidal outflow. River discharge increased from neap to spring tides causing a subsequent increase of seaward subtidal currents. During spring tide, D4 was generated by tidal advective accelerations and quadratic friction combined with river discharge, rather than by internal asymmetry. The sixth-diurnal overtide (D6) in the flow was comparable to D4 for both neap and spring tides. Largest D6/D23 ratios were found in the shallowest cross-channel locations during both neap and spring tides.
