COASTAL HAZARDS 2 Flashcards
marks the boundary between the sea and land
Shoreline-
zone affected by wave action
Shore-
this part of the shore is nearest to the sea. It is under water even at low tide.
Offshore-
between the low-tide breaker line and the low-tide shoreline
Nearshore-
this refers to the zone between high tide and low tide. It is under water during high tide. It is the surf zone.
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Foreshore-
it is the part of the shore between the high tide and the highest water level, which can only be reached by exceptional storm waves. Its sea bedis strewn with shingle and pebbles.
Backshore-
are areas where tectonic forces deform and uplift the land. They are usually rugged and irregular, with beaches sometimes being restricted to coves and inlets. Ex. Pacific Coast of US, Eastern Coast of Philippines fronting the Philippine Trench
Active shorelines
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are areas with little to no tectonic activity, commonly resulting in a relatively straight coastline with flat-lying terrain. Ex. U.S. Gulf and Atlantic Coasts
Passive shorelines
are the outer margins of the continents, where continental crust transitions to oceanic crust.
Continental Margins
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- are geologically inactive regions located some distance from plate boundaries.
- relatively wide and are sites where large quantities of sediments are deposited.
- comprises features such as the continental shelf, continental slope, and continental rise.
Passive Continental Margin
- are located along convergent plate boundaries, where oceanic lithosphere is being subducted beneath the leading edge of a continent
Active Continental Margin
Characterized by a single high tide and single low tide each tidal day
Diurnal (diurnal=daily)
exhibits single two high tides and two low tides each tidal day
Common along the Atlantic coast of the United States
Semidiurnal (semi=twice)
there are usually two high and two low tides each day, with high tides of different heights and low tides of different heights
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prevalent along the Pacific coast of the United States and in many other parts of the world
Mixed tidal pattern
Factors that determine size and energy of waves:
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The faster the wind speed, the greater the wave energy.
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The longer the wind blows, the larger the waves.
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The greater the fetch, the more energy the waves have.
Wind energy
Duration of wind
Fetch
–water from a breaker washing upon a beach at whatever angle the breaker approached shore.
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Swash
takes the shortest path, direct to the sea, not an oblique angle as taken by swash.
Backwash
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Stronger swash and weaker backwash.
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Occurs on gentle-sloping coasts.
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Deposits materials on the beach more than it removes.
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Constructive Waves
Occurs on steep-sloping coasts.
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Removes (erodes) materials on the beach more than it deposits.
Destructive Waves
As the wave continues toward shore, this causes a progressive decrease in velocity along the length of the wave, forcing it to bend in a process called
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wave refraction.
is a wave whose amplitude reaches a critical level at which some process can suddenly start that causes large amounts of wave energy to be transformed into turbulent kinetic energy.
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Breaking wave
refers to the area where the waves break.
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Surf zone
is an ocean current that flows parallel to the shore and is caused by large swells (series of waves) sweeping into the shoreline at an angle and pushing down the length of the beach in one direction.
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Longshore current
is the process of transporting material along a coast by waves which approach at an angle to the shore but recede perpendicular from it.
Longshore drift or beach drift
This interaction between waves and a landmass can cause the shoreline to slowly move landward, a process referred to as
shoreline retreat.
Also known as a sandy isthmus
Tombolos
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Sites of mud and organic deposition
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Quiet waters
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Some are enclosed by barriers and spits
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A combination of river processes and coastal processes
Lagoons, Mudflats, Marshes, and Mangrove Swamps
are wet lands that form as rivers empty their water and sediment into another body of water,such as an ocean, lake, or another river.
Deltas
Types of Deltas
There are two major ways of classifying deltas. One considers the influences/processesthat create the landform, while the other considers its shape.
-the movement of waves controls a delta’s size and shape.
Wave-dominated delta
-usually form in areas with a large tidal range, or area between high tide and low tide.
Tide-dominated delta
-are formed as rivers deposit large, coarse sediments. Gilbert deltas are usually confined to rivers emptying into freshwater lakes.
Gilbert deltas
-form as a river does not empty directly into the ocean, but instead forms a partly enclosed wetland that contains a brackish water habitat.
- Estuarine delta
Deltas with this triangular or fan shape are called _______(arc-like) deltas.
arcuate
Stronger waves form a ___________, which is more pointed than the arcuate delta, and is tooth-shaped.
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cuspate delta
A ___________has few, widely spaced distributaries, making it look like a bird’s foot.
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bird-foot delta
Another untraditional looking delta is the__________. The distributary network of an inverted delta is inland, while a single stream reaches the ocean or other body of water.
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inverted delta
_______________, which empty into a plain, are extremely rare.
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Inland deltas
An ______________ forms as a river develops a new channel, leaving the other to dry up or stagnate. This process is called avulsion.
abandoned delta
-this type is directly attached to a shore, or borders it with an intervening shallow channel or lagoon
FRINGING REEF
-a reef separated from a mainland or island shore by a deep channel or lagoon
BARRIER REEF
-this more or less circular or continuous barrier reef extends all the way around a lagoon without a central island.
ATOLL REEF
–observed where a more resistant portion of the rock remains in the surf, separated from the retreating cliff
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Sea stacks
Column of rock standing in the water off a beach
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Chimney-
where wave erosion has hollowed out a line of weakness in otherwise resistant promontory
Sea arch–
are gently sloping platform of rocks that extend seaward in to a steep drop off.
Shore Platforms
commonly leads to inland flooding far from where a storm makes landfall.
Intense precipitation
- a tool that measures the vulnerability of the physical coast by analyzing natural and anthropogenic factors driving beach processes
CIVAT
- Coastal Integrity and Vulnerability Assessment Tool
