Lateral Circulation in a Partially Stratified Tidal Inlet

Abstract

Using a three-dimensional, hydrostatic, primitive-equation ocean model, this study investigates the dynamics of lateral circulation in a partially stratified tidal inlet, the Barataria Pass in the Gulf of Mexico, over a 25.6 h diurnal tidal cycle. Model performance is assessed against observational data. During flood tide, the lateral circulation exhibits the characteristics similar to those induced by differential advection, i.e., lateral flow consists of two counter-rotating cells and is convergent at the surface. The analysis of momentum balance indicates that, in addition to the pressure gradient and vertical stress divergence, nonlinear advection and horizontal stress divergence are also important contributors. During ebb phase, the lateral circulation is mostly toward the right shoal (when looking into the estuary) for the whole water column and persisting for almost the whole period. The surface divergence suggested by the differential advection mechanism lasts for a very short period, if it ever exists. The main momentum balance across most of the transect during ebb is between the along-channel advection of cross-channel momentum and pressure gradient. The sectional averaged lateral velocity magnitude during ebb is comparable to that during flood, which is different from the idealized numerical experiment result.

Imminent reversal of the residual flow through the Marsdiep tidal inlet into the Dutch Wadden Sea based on multiyear ferry-borne ADCP observations

“…The direction of the gyre pattern corresponds with that observed by Nunes and Simpson (1985) during the flood phase of the tide in an estuary in Wales (UK), and explained by strong friction with the sides of the channel. Cui et al (2018) observed this pattern as well in an estuary in the Gulf of Mexico, where they also observed the reverse pattern during the ebb phase. So it is possible that, in a flood dominant estuary like the Marsdiep, the flood-phase pattern is expressed in the long-term mean as we see in the observations presented here.…”

Transport Processes in the Gulf of Mexico Along the River-Estuary-Shelf-Ocean Continuum: a Review of Research from the Gulf of Mexico Research Initiative

“…For example, measurements in tidal inlets have indicated a bathymetric control on exchange flows and atmospherically forced flows whose magnitude may exceed that of tidal flows (e.g., Li et al 2011;Olabarrieta et al 2017). Exchange flows tend to be laterally sheared under weakly stratified (top-to-bottom density differences < 2 kg/m 3 ) or vertically mixed conditions, and vertically sheared otherwise (Valle-Levinson 2011;Huguenard et al 2015;Valle-Levinson et al 2015;Cui et al 2018). Deep ship channels were also shown to be a critical pathway by which offshore subsurface material could be rapidly transported into estuarine systems (Coogan et al 2019).…”

“…2). FVCOM simulations also revealed the along-and cross-inlet circulation features at the main inlet (Barataria Pass) of Barataria Bay (Cui et al 2018), the tidal and wind modulation of the estuarine plume (Cui 2018), sediment erosion, transport and deposition patterns (Sorourian 2019), dynamics of coastal hypoxia (Justić and Wang 2014) and oil transport and fate (Huang et al in review).…”

“…The effects of river diversions on wetland-estuarinecoastal exchanges in Barataria and Breton Sound estuaries were studied using high-resolution coupled estuarine-coastal models (e.g., FVCOM, Huang et al 2011;Cui et al 2018). Model simulations suggested that the peak discharge from the Caernarvon diversion (~ 200 m 3 /s) into Breton Sound enhances water exchange between wetlands and adjacent water bodies, substantially increasing water velocity in the bayous and channels within 20-25 km of the diversion structure (Huang et al 2011;Huang et al in review).…”

“…3) for 3 months is predicted to greatly reduce estuarine residence times, especially in the lower reaches of Barataria Bay, with the average salinity exhibiting a ~ 12 point reduction near the Barataria Pass compared to a scenario with no diversion (Cui 2018). Furthermore, the area experiencing decreased salinities is larger along the bottom (near the bed) than at the surface, suggesting that the density gradients in the estuary would also change if a large-scale Mid-Barataria diversion is implemented (Cui et al 2018).…”