Chesapeake Bay Physical Model Investigations of Salinity Response to Neap-Spring Tidal Dynamics: A Descriptive Examination

Granat, Mitchell A.; Richards, David R.

doi:10.1016/b978-0-12-761890-6.50032-0

Cited by 3 publications

(2 citation statements)

References 5 publications

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“…In Barataria Pass, Louisiana, a 101-day ADCP record revealed that baroclinic currents were strongly coupled with tidal current amplitudes over fortnightly timescales, with greatest velocity shear occurring during equatorial tides when current amplitude was minimal [38]. These observational findings have been corroborated numerically, where order-of-magnitude reductions in vertical diffusivity have been found to occur following the transition from spring to neap tides [50], and also with physical models, where inverse relations between tidal amplitude and vertical salinity stratification have been documented for Chesapeake Bay [51].…”

Section: Vertical Variation In Subtidal Velocity Dtructure At Cocodriesupporting

confidence: 65%

Drivers of Barotropic and Baroclinic Exchange through an Estuarine Navigation Channel in the Mississippi River Delta Plain

Snedden

2016

Water

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Estuarine navigation channels have long been recognized as conduits for saltwater intrusion into coastal wetlands. Salt flux decomposition and time series measurements of velocity and salinity were used to examine salt flux components and drivers of baroclinic and barotropic exchange in the Houma Navigation Channel, an estuarine channel located in the Mississippi River delta plain that receives substantial freshwater inputs from the Mississippi-Atchafalaya River system at its inland extent. Two modes of vertical current structure were identified from the time series data. The first mode, accounting for 90% of the total flow field variability, strongly resembled a barotropic current structure and was coherent with alongshelf wind stress over the coastal Gulf of Mexico. The second mode was indicative of gravitational circulation and was linked to variability in tidal stirring and the horizontal salinity gradient along the channel's length. Tidal oscillatory salt flux was more important than gravitational circulation in transporting salt upestuary, except over equatorial phases of the fortnightly tidal cycle during times when river inflows were minimal. During all tidal cycles sampled, the advective flux, driven by a combination of freshwater discharge and wind-driven changes in storage, was the dominant transport term, and net flux of salt was always out of the estuary. These findings indicate that although human-made channels can effectively facilitate inland intrusion of saline water, this intrusion can be minimized or even reversed when they are subject to significant freshwater inputs.

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Section: Vertical Variation In Subtidal Velocity Dtructure At Cocodriesupporting

confidence: 65%

Drivers of Barotropic and Baroclinic Exchange through an Estuarine Navigation Channel in the Mississippi River Delta Plain

Snedden

2016

Water

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“…Wang and Kravitz (1980) made numerical experiments on the Potomac River in which the river flow was changed, but these were not run out long enough to determine an adjustment time (the salinity was still dropping rapidly 2.5 days after the river flow was increased). Granat and Richards (1986) and Richards and Granat (1986) made time-dependent experiments in a large laboratory model of Chesapeake Bay. In general they found that increased tidal amplitude decreased stratification, while increased river flow increased the stratification and pushed the salt intrusion seaward.…”

Section: Introductionmentioning

confidence: 99%

Estuarine Adjustment to Changes in River Flow and Tidal Mixing

MacCready¹

1999

J. Phys. Oceanogr.

149

103

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The adjustment of estuarine circulation and density to changes in river flow and tidal mixing is investigated using analytical and numerical models. Tidally averaged momentum and salinity equations in a rectangular estuary are vertically averaged over two levels, resulting in equations that are analytically tractable while retaining a broad range of time-dependent behavior. It is found that both strongly stratified and well-mixed estuaries respond rapidly to either type of forcing change, while those of intermediate stratification respond more slowly. Intermediate estuaries also have the greatest sensitivity to change. Exchange flow dominates the up-estuary salt flux in strongly stratified cases. Changing the river flow in such cases leads to an internal wave propagating the length of the estuary, which accomplishes much of the adjustment. The internal wave speed thus controls the adjustment time. Increased tidal mixing in strongly stratified cases initially decreases the exchange flow contribution to up-estuary salt flux by decreasing both the stratification and the vertical current shear. However, the decreased up-estuary salt flux leads to a loss of total salt in the estuary, and hence a greater longitudinal salinity gradient. The increasing gradient eventually restores the exchange-flow salt flux to near its original value. Well-mixed solutions have an advective-diffusive balance between river flow and longitudinal tidal mixing. In these cases the adjustment time corresponds to the time it takes the depth-averaged flow to travel the length scale of the salt intrusion, a result that applies to both types of changes considered. In all cases the adjustment depends upon the dynamical feedback between the longitudinal salt flux and the longitudinal salinity gradient, which varies as the estuary gains or loses total salt.

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Salinity Redistributions in Deepened Estuaries

Richards

Granat

1986

Estuarine Variability

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Chesapeake Bay Physical Model Investigations of Salinity Response to Neap-Spring Tidal Dynamics: A Descriptive Examination

Cited by 3 publications

References 5 publications

Drivers of Barotropic and Baroclinic Exchange through an Estuarine Navigation Channel in the Mississippi River Delta Plain

Drivers of Barotropic and Baroclinic Exchange through an Estuarine Navigation Channel in the Mississippi River Delta Plain

Estuarine Adjustment to Changes in River Flow and Tidal Mixing

Salinity Redistributions in Deepened Estuaries

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