Dynamics of water and salt exchange at Maryland Coastal Bays

Abstract

The exchange processes between the Maryland Coastal Bays system (MCBs) and their adjacent coastal ocean were simulated using a three-dimensional unstructured-grid based hydrodynamic model, which was validated by observed data including water level, current velocity and salinity. Idealized experiments were then carried out to investigate the impact of wind forcing on water exchange and salt flux. Through these experiments, the exchanges between the MCBs and coastal ocean were investigated at two inlets (Ocean City Inlet and Chincoteague Inlet). Given that winds and tides are two key external forces known to impact estuarine dynamics, the effect of each individual force on the exchange processes was studied to evaluate the corresponding influence on the inlet dynamics. It was found that wind forcing significantly impacts the inlet dynamics: the effect of wind directions on exchange processes under strong wind speeds is substantial; for example, northwesterly winds push flux to the southern part of the bays, while southwesterly winds pile up flux towards northern Chincoteague Bay. The effect of wind forcing on the exchange dynamics becomes stronger with the augmentation of its speed. Meanwhile, tidal forcing is the major driver of exchange dynamics at weak wind speeds (e.g., 3 m/s), and its effect on exchange process gradually weakens with stronger wind speeds (e.g., 7 m/s, 15 m/s). In addition, sensitivity tests elucidated that closing either inlet results in a significant impact on the water elevation, current velocity and salinity nearby the relevant cutoff inlet areas.

Role of Baroclinic Processes on Flushing Characteristics in a Highly Stratified Estuarine System, Mobile Bay, Alabama

“…Their relative importance varies greatly among different systems, depending on the tidal range, magnitude of freshwater input, and the estuarine geometry and bathymetry. Wind forcing typically modulates the primary exchange mechanisms; however, in some systems, it can be a dominant factor (Feng & Li, ; Geyer, ; Kang et al, ). System flushing for an estuary is derived from both river and ocean inputs.…”

Wave–current dynamics and interactions near the two inlets of a shallow lagoon–inlet–coastal ocean system under hurricane conditions

“…They encompass five sub-bays that include Assawoman Bay, Isle of Wight Bay (upper bays), Sinepuxent Bay, Newport Bay, and Chincoteague Bay (lower Bays), see Fig. 1a and Kang et al (2017). The MCBs communicate with the adjacent Atlantic Ocean via the Ocean City Inlet (OCI) and Chincoteague Inlet (CI).…”

“…Inlet and its wave-current dynamics are critical to the residence time (Defne and Ganju, 2015), particle transport (Xia et al, 2011), drifter spreading (Spydell et al, 2015), and material exchanges (Allen et al, 2007;Ferrarin et al, 2013;Umgiesser et al, 2014;Kang et al, 2017) in a lagoon-inlet-coastal ocean system. Based on the relationship between tidal ranges and mean wave heights, inlets are classified into three types: tide-dominated, wave-dominated, and mixed-energy (Hayes, 1979).…”

“…The conceptual model used by Orescanin et al (2014), however, is limited within an idealized system owing to the simplification of model domain and the assumption of a uniform wind field. Using the unstructuredgrid-based model with spatiotemporally varying winds, Fabião et al (2016) and Kang et al (2017) identified that wind direction significantly impacts water exchanges of the complex multipleinlet system, especially under strong wind conditions. However, both models were tested in the absence of waves, which play a prominent role in the inlet circulation and should be taken into account (Wargula et al, 2014).…”

Dynamics of Mesozooplankton Assemblage in Relation to Environmental Factors in the Maryland Coastal Bays

“…The MCBs located in the Mid-Atlantic region on the east coast of the United States is separated from the Atlantic Ocean by barrier islands. This lagoonal system consists of five embayments ( Figure 1) that are well mixed mostly by wave and tidal actions that facilitate the exchange of water and materials between the MCBs and the nearby coastal ocean [29,33]. The system, however, is poorly flushed, has low freshwater input from groundwater, rivers and tributaries, and therefore high salinity that is close to that of the ocean except in upstream areas of rivers and creeks [28,29].…”