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Salinity, Tides, and Circulation

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Chesapeake Bay

Salinity, Tides and Circulation

Water is the lifeblood of the Bay

Organic - carbon containing

Inorganic - minerals, dissolved gases nutrients

supports - planktonic forms ( zooplankton )

Dynamic interaction of freshwater input, salinity, tidal flow

Understand fluctuating conditions


Freshwater Input

18 trillion gallons of water. Drain it would take a year to refill it.

70,000 cubic feet ( 2,000 cubic meters ) each second flow into bay form tributaries

1/9 of volume of seawater flowing into Bay at any instant

Storm pulse like a transfusion

Bay watershed spans 64,000 square miles

6 surrounding states

Susquehanna River 50 % of Bay’s freshwater drainage

Second reason - out of 150, 46 major tributaries, 8 of these contribute 90 % of freshwater inflow.

On the western side of the Bay: Potomac, James, Rappahannock, York, Patuxent, and West Chesapeake Drainage

Primary: Susquehanna - flows from north

Drains part of Eastern shore: Choptank

Chesapeake is right handed and top heavy as far as freshwater

8 major rivers and ocean: Shapes circulation and salinity character of Bay



From Susquehanna to mouth of Bay = Zero 0 to almost marine

Define salinity: 35 g of dissolved salts/ kg of water

brackish salinity ?

freshwater salinity ?

Buoyancy difference and layers

salinity gradient - sun, moon,earth’s rotation


Coriolis force




Phases of the moon

Tidal movement

Tidal ebb

high tide and low tide

Size and depth of basin

Semidiurnal tidal pattern

Tidal currents and horizontal movements

Vertical range



Two - layer estuarine flow


Zone of turbidity

Entrainment velocity


Retention Time



Home for organisms " residents "


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