Ocean Tide

Ocean Tides : 

Ocean Tides An ocean tide refers to the cyclic rise and fall of seawater. Tides are caused by slight variations in gravitational attraction between the Earth and the moon and the sun in geometric relationship with locations on the Earth's surface. Tides are periodic primarily because of the cyclical influence of the Earth's rotation. Moon 6.2 million km. from Earth

Slide 2: 

St. Michel, N. coast of France ~16.8 m highest tidal range in Nova Scotia

Nova Scotia Tides : 

Nova Scotia Tides Wolfville, NS (16 m tidal range) Diurnal Tides (one high and one low every 12 hours and 25 minutes

Slide 4: 

Second highest tidal range at Ancorage Alaska ~ 12 m

Variable Tides : 

Variable Tides

Lunar and Solar Parallax : 

Lunar and Solar Parallax

Types of Tides : 

Types of Tides Spring: 1 st. and 3 rd. quarters Neap: new and full moon

Spring and Neap Tides : 

Spring and Neap Tides

Semidiurnal, Mixed and Diurnal Tides : 

Semidiurnal, Mixed and Diurnal Tides

Tidal Ranges Around the Globe : 

Tidal Ranges Around the Globe

Tides Around the Globe : 

Tides Around the Globe

Tide Curve off Grand Isle : 

Tide Curve off Grand Isle

Inlets/Inlet Morphology : 

Inlets/Inlet Morphology Inlet Dynamics determined by Tidal currents Wave currents Longshore sediment supply Antecedent geology

Tidal Prism/X-Sectional Area : 

Tidal Prism/X-Sectional Area TIDAL PRISM Total amount of H2O flowing into or out of an inlet with the rise and fall of the tide.

Slide 15: 

AC = 2.00 x 10-5 P (O’Brien, 1931, 1969) AC = 5.44 x 10-6 P1.06 (Jarrett, 1976) NB: Changes in bed shear and littoral supply. Maximum Inlet Velocity Concept (Escoffier, 1940, 1972) Maximum velocity curve exists at inlets, along with a critical x-section area (AC*).

Inlet By-Passing of Sediment(Bruun, 1966) : 

Inlet By-Passing of Sediment(Bruun, 1966) Ratio of net littoral drift to maximum discharge through inlet. r = MNET/QMAY MNET = Net littoral drift (yds3/yr.) QMAX = Maximum discharge (yds3/sec.) r < 10-20 Tidal flow bypassing r > 200-300 Bar bypassing NOW USED: r = W/MTOT W = Tidal prism (m3/tidal cycle) MTOT = Total/gross drift (m3/yr.)

Sediment Sources for Ebb Shoals : 

Sediment Sources for Ebb Shoals Longshore transport Onshore transport Inlet gorge

Slide 18: 

Idealized Free Jet Flowing Through an Orifice into a Frictionless Receiving Basin Sectional View of Free Jet Illustrating Seabed Response at Near Field and Far Field

Hypopycnal Flow : 

Hypopycnal Flow Plane jet flow with the reservoir fluid more dense than the inflowing fluid. This situation is characteristic of rivers flowing into oceans. Modified from Bates (1953) By A.J. Scott.

Slide 20: 

Hyperpycnal Flow A plane jet in which the inflowing fluid is more dense than the reservoir fluid. This is the situation prevalent in turbidity flows. Modified from Bates (1953) By A.J. Scott.

Slide 21: 

Homopycnal Flow Axial jet flow in which the inflow and reservoir fluids have the same density. Rapid mixing associated with this type of inflow results in deposition of Gilbert-type deltas. Modified from Bates (1953) By A.J. Scott.

An Idealized Inlet : 

An Idealized Inlet

An Inlet System Showing Diversion of Littoral Drift : 

An Inlet System Showing Diversion of Littoral Drift

Types of Ebb Tidal Deltas(after Oertel, 1975) : 

Types of Ebb Tidal Deltas(after Oertel, 1975)