Coastal Hazards Flashcards
(121 cards)
1
Q
It is the strip of land bordering the sea or ocean along a continent or an island
A
coast/shore
2
Q
It marks the seaward limit of the landmass, which is permanently exposed to wave action
A
coastline/shoreline
3
Q
What are the chief agents shaping our coastlines.
A
Waves, currents, tides and winds
4
Q
It marks the boundary between the sea and land
A
Shoreline
5
Q
A zone affected by wave action
A
Shore
6
Q
This part of the shore is nearest to the sea. It is under water even at low tide
A
Offshore
7
Q
It is between the low-tide breaker line and the low-tide shoreline
A
Nearshore
8
Q
This refers to the zone between high tide and low tide. It is under water during high tide. It is the surf zone.
A
Foreshore
9
Q
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 bed is strewn with shingle and pebbles
A
Backshore
10
Q
These 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.
A
Active shorelines (Ex. Pacific Coast of US, Eastern
Coast of Philippines fronting the
Philippine Trench)
11
Q
These are areas
with little to no tectonic activity,
commonly resulting in a
relatively straight coastline with
flat-lying terrain.
A
Passive shorelines (Ex. U.S. Gulf
and Atlantic Coasts)
12
Q
True or False: Active shoreline can evolve into passive shoreline
A
True
13
Q
It is the measurements of the differences in elevations of points relative to the sea level along a straight line perpendicular to the shoreline, as well as the identification and characterization of the geological materials along and at the vicinities of the profile line.
A
Beach profiling
14
Q
It is an equipment that is used in beach profiling
A
berm
15
Q
True or False: Continental shelf, slope, and rise features of a continental margin can only be found at passive continental margins.
A
False: These features can also be found at active continental margins however they are usually narrow and have steep continental slopes and either poorly developed continental rises or none at all.
16
Q
These are the outer margins of the continents, where continental crust
transitions to oceanic crust.
A
Continental Margins
17
Q
These are geologically inactive regions located some distance from plate
boundaries.
These are relatively wide and are sites where large quantities of sediments
are deposited
A
Passive Continental Margins
18
Q
These are located along convergent plate boundaries, where oceanic
lithosphere is being subducted beneath the leading edge of a continent
A
Active Continental Margins
19
Q
Parts or Features of a Continental Margin?
A
Continental Shelf
Continental Slope
Continental Rise
20
Q
The continental shelf has an average slope of ________________, while the continental slope has an average slope of about _________.
A
one-tenth of 1 degree, 5 degrees
21
Q
These develop along subduction zones where sediments from the ocean floor are scrapped from the descending oceanic plate and pressed against the edge of the overriding plate.
A
Accretionary Wedge
22
Q
Another important process
that affects the nature of
shorelines is the relative
movement of the shoreline
either __________ or __________.
A
seaward, landward
23
Q
Shorelines also shift in
response to worldwide
changes in sea level that occur
when Earth’s global climate
alternates between cool,
glacial periods and warm
periods called _____________.
A
interglacials
24
Q
The periodic rise and fall of sea level is known as ____________ and is caused by the spinning motion of the Earth, combined with the gravitational interaction between the Earth, Moon,
and Sun
A
ocean tides
25
___________ refers to the difference in sea level between high and low tides.
Tidal range
26
This occurs when the Moon and Sun periodically line up such that their gravitational effects reinforce one another.
Spring tide
27
This occurs when the gravitational pull of the Moon and Sun are at right angles which tend to cancel their tidal effects on one another.
Neap tide
28
True or False: Moon has a greater tidal influence than the Sun.
True: Moon has a greater tidal influence because it is much closer to the Earth than the Sun.
29
Three main tidal patterns exist worldwide, namely?
Diurnal
Semidiurnal
Mixed tidal pattern
30
It is characterized by a single high tide and single low tide each tidal day.
Diurnal (diurnal=daily)
31
It exhibits single two high tides and two low tides each tidal day
which is common along the Atlantic coast of the United States.
Semidiurnal (semi=twice)
32
It is similar to semidiurnal pattern except that it is characterized by a large inequality in high water heights, low water heights, or both. There are usually two high and two low tides each day, with high tides of different heights and low tides of different heights. It is pevalent along the Pacific coast of the United States and in many other parts of the world
Mixed tidal pattern
33
These are strong localized currents during high tide formed by the surface of the sea sloping towards the shore which generates mechanical energy that forces water to funnel up into inlets and river channels.
Tidal currents
34
These involve the physical movement of water molecules from one location to another. These are driven by various forms of energy, and like all things in motion, currents flow from an area of high energy to one of lower energy.
Ocean currents
35
These are large-scale currents in the open water near the surface of the sea which are driven mainly by winds blowing consistently in the same direction.
Surface currents
36
These are formed in response to differences in ocean temperature and salinity. Cooler and more saline water is relatively dense which causes it to sink and flow toward areas where water is less dense.
Density currents
37
_____________ transport energy through water such that water molecules move or vibrate in a circular manner.
Water waves
38
It is the depth where water molecules are no longer affected by the passing wave. It is equal to about one-half of the wave’s wavelength (distance between successive crests)
Wave base
39
The energy of wind-generated waves is also affected by the amount of contact area between the wind and water, called _______, and the duration of the wind.
fetch
40
Factors that determine size and energy of waves:
• Wind energy
- The faster the wind speed, the greater the wave energy.
• Duration of wind
- The longer the wind blows, the larger the waves.
• Fetch
- The greater the fetch, the more energy the waves have.
41
This is the rush of water from a breaker washing upon a beach at whatever angle the breaker approached shore
Swash
42
The swash water retreating back under the influence of gravity.
Backwash
43
True or False: Backwash takes the longest path, indirect to the sea, and oblique angle as taken by swash.
False: Backwash takes the shortest path, direct to the sea, not an oblique angle as taken by
swash.
44
It has stronger swash and weaker backwash, and occurs on gentle-sloping coasts.
It deposits materials on the beach more than it removes.
Constructive Waves
45
It has stronger backwash and weaker swash, and occurs on steep-sloping coasts. It removes (erodes) materials on the beach more than it deposits.
Destructive Waves
46
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 _____________.
wave refraction
47
It 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.
Breaking wave
48
___________ refers to the area where the waves break
Surf zone
49
It 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.
Longshore current
50
It 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
51
________________ can travel farther inland than the normal waves,
this is due to the increased local sea level during storm events.
storm waves/surges
52
These are large waves caused by the sudden mid/under sea displace of a large volume of water.
Tsunami
53
This interaction between waves and a landmass can cause the shoreline to slowly move landward, a process referred to as ______________.
shoreline retreat
54
This is the accumulations of sediment deposited by waves and longshore currents in the shoreline; well-sorted
Beach
55
4 main sources for beach sediment:
• Local cliffs and promontories
• The offshore zone
• Calcareous sand and shell fragments from coral and mollusc debris
• Local river bedload material
56
These are elongate deposits of sediment which parallel the shore and are separated from the mainland by open water, lagoons, tidal mudflats, or saltwater marshes
Barrier islands
57
Barrier islands result from the complex interaction between these three.
waves, sea level change, and sediment supply.
58
It is generally
believed that barrier islands originate when wave action causes
sand to accumulate offshore, forming shallow ___________. Enough sand eventually accumulates to where the bar stays above
the high tide line, thereby creating a ____________.
sand bars, true island
59
It is a beach that is tied to the coast at one end and free
at the other; grows across bay mouths in the direction
of predominant longshore sediment drift and aligns itself nearly at right angles to the prevailing wind
direction
Spit
60
__________, also known as a _________, are depositional landforms by which an island becomes attached to the mainland by a spit or bar.
These are sediment
deposits at the coast formed by wave refraction and diffraction at the edges of an obstacle (natural or artificial) originally detached from the mainland.
Tombolos, sandy isthmus
61
Explain how Tombolos are formed.
1st. The process of longshore drift transports materials along the coast until the direction changes abruptly
or bends.
2nd. The materials are then deposited in the same direction seawards.
3rd. As the spit continues to grow and joins a nearby offshore island, a
tombolo is formed.
62
These are formed when sand deposited off the shore dries out and blown out to the back of the
beach.
Coastal Dunes
63
Coastal Dunes usually needs:
• Large tidal range
• Broad intertidal zones
• Large supply of sand
64
These are sites of mud and organic deposition, quiet waters, some are enclosed by barriers and spits, and a combination of river processes and coastal processes.
Lagoons, Mudflats, Marshes, and Mangrove Swamps
65
_________ are wetlands that form as rivers empty their water
and sediment into another body of water, such as an ocean, lake, or another river. Although very uncommon, these can also empty into land.
Deltas
66
There are two major ways of classifying deltas. One considers the ______________ that create the landform, while the other considers its _______.
influences/processes, shape
67
It is a delta which the movement of waves controls the delta's size and shape.
Wave-dominated delta
68
This delta usually form in areas with a large tidal range, or area between high tide and low tide.
Tide-dominated delta
69
These deltas are formed as rivers deposit large, coarse sediments. These are usually confined to rivers emptying into freshwater lakes
Gilbert deltas
70
This delta 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
71
The term delta comes from the upper-case Greek letter delta (Δ), which is shaped like a triangle. Deltas with this triangular or fan shape are called ____________________.
arcuate (arc-like) deltas
72
Stronger waves form a _______________, which is more pointed than the arcuate delta, and is tooth-shaped.
cuspate delta
73
A _______________ has few, widely spaced distributaries, making it look
like a bird's foot.
bird-foot delta
74
Another untraditional looking delta is the ____________. The distributary network of this delta is inland, while a single stream reaches the ocean or other body of water.
inverted delta
75
A type of delta in which empties into a plain. This type of delta is extremely rare.
Inland deltas
76
An _____________ forms as a river develops a new channel, leaving
the other to dry up or stagnate. This process is called _____________.
abandoned delta, avulsion
77
It is a rock, sandbar, or other feature lying beneath the surface of the water (six fathoms or less beneath low water)
Reefs
78
Many reefs result from abiotic processes—deposition of sand, wave erosion planning down rock outcrops, and other natural processes—but
the best-known reefs are the ____________ of tropical waters developed through biotic processes dominated by corals and calcareous algae
coral reefs
79
These are underwater structures
made from calcium carbonate secreted by corals. Often called “rainforests of the sea”, these form some of the most diverse ecosystems on Earth.
Coral reefs
80
True or False: Reefs grow best in warm, shallow, clear, sunny and agitated waters
True
81
most coral reefs are less than __________ years old
10,000
82
In 1842, He set out his theory about the formation of atoll reefs. He theorized uplift and subsidence of the Earth's crust under the oceans formed the atolls
Charles Darwin
83
Darwin’s theory sets out a sequence of 3 stages in Atoll formation. What are those?
• FRINGING REEF
• BARRIER REEF
• ATOLL REEF
84
Explain briefly how Atolls form.
It starts with a fringing reef forming around an extinct volcanic island
as the island and ocean floor subsides.
As the subsidence continues, the fringing reef becomes a barrier reef, and ultimately an atoll reef.
85
This type of reefs is directly attached to a shore, or borders it with an intervening shallow channel or lagoon.
Fringing Reef
86
It is a reef separated from a mainland or island shore by a deep channel or lagoon.
Barrier Reef
87
This more or less circular or continuous barrier reef extends all the way around a lagoon without a central island.
Atoll Reef
88
Marine erosion takes place mainly during storms and as a result of
__________.
wave action
89
The repetitive hydraulic action slowly breaks the rocks apart and
forms a _____________ within the cliff face.
notch or undercut
90
As the notch deepens the overhanging cliff becomes less stable, eventually causing the slope to fail in a mass wasting event, at which point the cliff face retreats landward. In some instances the hydraulic pressure from crashing waves will slowly bore a hole
through a cliff face, forming a _________.
sea arch
91
These are observed where a more resistant portion of the rock remains in the surf, separated from the retreating cliff.
Sea stacks
92
Column of rock standing in the water off a beach.
Chimney
93
It is a coastal erosional feature where wave erosion has hollowed out a line of weakness in otherwise resistant promontory.
Sea arch
94
These are places where waves first
make contact with land and with the
greatest amount of energy; these are
the places where erosion is high
Headlands
95
These are gently sloping platform of rocks that extend seaward in to a
steep drop off
Shore Platforms
96
As the waves refract around both sides of the headlands, eroded material is transported into coves via longshore currents where it is deposited, forming _______________.
isolated beaches
97
Dominant Influences on Coastal Landforms:
• Type of Continental Margin
• Relief, Structure, and Lithology
• Climatic Influences
• Rates of Erosion
• Sea Level
98
Edges of actively diverging plates are rifted and block faulted, and consequently tend to be relatively straight with few embayments. These forms passive margins with continental shelves
Divergent Boundaries
99
Characterized by Islands
such as Philippines, Indonesia, and Japan.
No Continental Shelves. Deep offshore trenches. Structural trend parallel to the line of convergence. With a line of a mountainous arcs
Pacific Type boundary
100
May have shallow and broad continental shelves e.g. North American Plate- Atlantic side
Atlantic-type Margins
101
True or False: The energy available for coastal processes is partially controlled by wave height, windspeed direction and duration. High energy coasts tend to have rocky beaches, severely eroded upland coasts. Low energy coasts tend to have deltas, salt marshes, or mangrove swamps.
True
102
True or False: Coasts between latitudes of 45° to 60° and east facing coasts in the tradewind belts generally have high storm induced swells.
True
103
Coastal positions have changed almost constantly through constant cycle of _________ and ___________.
glaciation and melting
104
This refer to large, rotating low pressure storm systems that
originate in tropical oceans.
Tropical cyclones
105
Winds and low pressure within a
hurricane produce a rise in sea level
called a _____________ and will also produce
heavy rains that commonly lead to river flooding.
storm surge
106
Different hurricanes are ranked based on their sustained winds, with the lowest category having winds of at least 74 miles per hour—anything less is called a __________________.
tropical storm or depression
107
Storm
surge has up to ________ rise in sea level.
9 meters
108
____________________ can now commonly predict out to 48 hours in advance
where a hurricane will make landfall and do so with a fairly high degree of
accuracy.
Forecasting models
109
These are unusually high-energy waves that form not from the wind, but rather by the transfer of energy from earthquakes, volcanic eruptions, landslides, or asteroids to a body of water.
Tsunami
110
True or False: Tsunamis traveling through deep ocean waters have short wavelengths, their wave base are shallow, wave height is quite large, and travels slower compared to Tsunamis approaching a coastline
False: Tsunamis traveling through deep ocean waters have exceptionally long wavelengths, typically from 6 to 300 miles (10–500 km), their wave base can be rather deep. Moreover, the height of these waves in deep water is quite small (less than a meter), but they travel at speeds of
over 500 miles per hour (800 km/hr).
111
______________ form when backwash from the surf zone funnels through a break in underwater sand bars
Rip currents
112
Should you ever find yourself being swept out to sea in a rip current, the best approach is to stay calm and swim parallel or perpendicular to shore?
parallel👍
113
These are solid walls made of resistant materials such as concrete, rocks, or wood built parallel and on the coast.
These are very effective in protecting the coast from erosion by absorbing the energy of waves.
Seawalls
114
These are solid walls usually made of granite built of and parallel to the coast, or with one end attached to the coast.
It causes waves to break against it before reaching the coast hence preventing coastal erosion.
It creates a zone of calm water behind them which encourages deposition and formation of beaches.
Breakwaters
115
These are solid walls usually made of granite or wood built on and perpendicular to the coast.
It absorbs or reduces wave energy and encourages deposition on the side of the this facing longshore drift.
Groynes/Groins
116
These are barriers made of large rocks and are installed at the mouth of an inlet to keep sediment from longshore current to clog channels, and thereby reducing dredging
costs. Note that this normally come in pairs because longshore currents will periodically reverse from their dominant direction.
Jetties
117
These are wire cages filled with small rocks piled up and placed along the coast. It absorbs wave energy and prevents coastal erosion. Cheaper to build.
Gabions
118
In many cases the only real solution to beach starvation is to manually add sand to the beach in a process called ___________________.
beach
nourishment
119
It is 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)
120
Other tools for assessing coastal vulnerability
• ICSEA-C-Change (Integrated Coastal Sensitivity, Exposure, and Adaptive
Capacity to Climate Change)
• TURF (Tool for Understanding Fisheries Resilience)
121
Sea level today is rising at a rate of _________________, but could increase dramatically should global warming
destabilize ice sheets on Greenland and Antarctica.
0.6 feet (0.2 m) per century
