Coastal Environments Flashcards
(83 cards)
1
Q
Coastal Processes
What are coasts?
A
Coasts are the meeting point of the land and sea and are an open system with inputs(sediment), transfers(longshore drift), stores(beach) and outputs(water).
2
Q
Coastal Processes
What is the fetch?
A
The distance the wind blows over the sea.
3
Q
Coastal Processes
What is hydraulic action?
A
Sheer force of the waves hitting the coast.
4
Q
Coastal Processes
What is attrition?
A
Material (rocks,shingle) are carried by the waves and bump against each other and are worn smaller and smoother. This type does not really erode the coast but forms shingles and sand.
5
Q
Coastal Processes
What is corrosion (or solution)
A
Seawater is slightly acidic and this gradually dissolves some types of coastal rock (limestone etc.)
6
Q
Coastal Processes
What is Abrasion?
A
Waves pick up material and hurl it at the coast.
7
Q
Coastal Processes
What are the 3 factors affecting the height and strength of waves?
A
- Fetch
- Amount of time wind blows
- Strength of wind
8
Q
Coastal Processes
What is traction?
A
Large heavy material is dragged along the sea floor.
9
Q
Coastal Processes
What is saltation?
A
Smaller material is bounced along sea floor.
10
Q
Coastal Processes
What is Suspension?
A
Fine material is held in water and travels along.
11
Q
Coastal Processes
What is solution?
A
Dissolved material is carried in water.
11
Q
Coastal Processes
What is longshore drift and can you explain the process?
A
- It is the main process of deposition and transportation along the coast.
- Influenced by prevailing wind, waves approach beach at angle.
- Swash carries material up the beach.
- As swash dies away, the backwash carries material down at a right angle due to the influence of gravity.
- The process repeats, transporting material along the beach in a zig-zag movement.
12
Q
Coastal Processes
What is weathering?
A
Breakdown of rocks in-situ (orginal place). Weathering does not involve the movement of material and this makes it different from erosion.
13
Q
Coastal Processes
What is sub-aerial weathering?
A
Are land-based processes and occur above the waterline. They include weathering and mass movement, which happen on the cliff rocks.
13
Q
Coastal Processes
Explain mechanical weathering (with example):
A
Mechanical weathering physically breaks up rock:
One example is freeze thaw weathering. This is when water gets into cracks and joints in the rock and freezes. This causes the cracks and joints in the rock to expand and over time pieces of rock break apart.
14
Q
Coastal Processes
Explain biological weathering:
A
Takes place when rocks are worn away by living organisms.
Trees and other plants can grow within cracks of rocks.
Animals can disturb ground.
15
Q
Coastal Processes
Explain chemical weathering:
A
Occurs when rocks are broken down by a chemical process.
Rainwater is slightly acidic through absorbing CO2 in the atmosphere.
This reacts with minerals in the rock.
Rock-type affects rate of weathering. (limestone is especially vulnerable)
16
Q
Coastal Processes
What is mass movement?
A
The downhill movement of material under the influence of gravity.
17
Q
Coastal Processes
What is sliding?
A
A movement of material which remains together until hitting the bottom of a slope.
18
Q
Coastal Processes
What is slumping?
A
Involves a large area of land moving down the slope in one piece. Due to the nature of the slip, it leaves behind a curved surface.
19
Q
Coastal Landforms
What is a headland?
A
Section of hardrock jutting out into the sea,
20
Q
Coastal Landforms
What is a bay?
A
Inlet of the sea where the land curves inwards.
Consist of soft rock/material.
21
Q
Coastal Landforms
What is a wave-cut platform?
A
A wide gently sloped surface found at the foot of a cliff,
22
Q
Coastal Landforms
Explain the formation of a headland:
A
Headlands are formed at discordant coastlines where there are alternating bands of hard rock and soft rock at right angles to the coastline, which means that the soft rock gets eroded faster than the hard rock (since it is less resistant) creating a bay and a protruding headland.
23
# Coastal Landforms
Explain the formation of a bay:
Bays are formed at discordant coastlines where there are alternating bands of hard rock and soft rock at right angles to the coastline, which means that the soft rock gets eroded faster than the hard rock (since it is less resistant) creating a bay and a protruding headland.
24
# Coastal Landforms
Explain the formation of a cliff:
Cliffs tend to be located on a headland due to erosion from wave action. The base of the cliff is eroded through a number of ways: Hydraulic action, abrasion and corrosion. The rock type will affect cliff gradient or steepness. Cliffs with soft rock are gently sloping while cliffs with hard rock are steep.
25
# Coastal Landforms
Explain the formation of a wave cut platform:
* Due to wave action (sea hitting) on the base of the cliff between the high and low water mark, wave-cut notch is formed.
* Abrasion, corrosion and hydraulic action further extend the wave cut notch back into the cliff.
* The undercutting of the cliff leads to instability and collapse of the cliff.
* Backwash of the waves carries away eroded material, leaving behind a wave cut platform.
* Process repeats and cliff continues to retreat.
26
# Coastal Landforms
Explain the formation of a cave, arch, stack and stump:
* Found on a headland due to wave action and sub-aerial weathering.
* Weakness in the headland are exploited on both sides by erosional processes of hydraulic action, abrasion and corrosion.
* Cracks begin to widen, abrasion will begin to wear away at the forming cave.
* The cave will become larger and eventually break through the headland to form an arch.
* The base of the arch continually becomes wider and thinner through erosion below and weathering from above.
* Eventually the roof of the arch collapses, leaving behind an isolated column of rock called a stack.
* The stack is undercut at the base by wave action and sub-aerial weathering above until it collapses to form a stump.
27
# Coastal Landforms
Explain the formation of a spit:
* Sediment is transported by longshore drift.
* Where coastline changes direction, shallow, shelted areas allow for deposition of sediment.
* Due to increased friction, more deposition occurs.
* Eventually a spit builds up to sea level and extends in length.
* If wind changes direction, wave pattern alters resulting in hooked end.
28
# Coastal Environment Change
What are the 4 influences affecting coastlines?
Influence of:
1. Geology
2. Vegetation
3. Sea-Level Changes
4. People
29
# Coastal Environment Change
How does Geology influence the coastline?
* Hard Rock: Coastlines of more resistant rock take longer to erode and produce rugged landscapes such as headlands.
* Soft Rock: Coastlines of less resistant rock erode quicjer and form low, flat landscapes like beaches and bays.
30
# Coastal Environment Change
How does Vegetation influence the coastline?
The largest influence of vegetation is to assist in protecting and preserving coastal landforms. Examples include sand dunes, salt marshes and mangroves.
31
# Coastal Environment Change
How does sea-level changes influence the coastline?
* Submersion: Rising sea levels produce submergent coastlines with rias and fjords.
* Emergence: Falling sea levels produce emergent coastlines with relic features such as raised beaches, cliffs with caves, arches etc.
32
# Coastal Environment Change
How do people influence the coastline?
* Settlement- Coasts have always been areas of attraction and resident.
* Economic Development: Exploitation through fishing, farming, trade, tourism and energy production.
* Coastal Management: Controlling coastline to protect human interests.
33
# Coastal Ecosystems around the world.
Explain the distribution of coral reefs:
Corals are scattered throughout the tropical and sub tropical Western Atlantic and Indo-Pacific oceans, generally within 30N and 30S degrees latitudes.
34
# Coastal Ecosystems around the world.
What are the features of coral reefs?
* Temperature- Corals cannot tolerate temps below 18 degrees celsius, but grow best at 23-29 degrees celsius.
* Light- Corals need light for photosynthesis
* Water- Corals are generally found at depths of less than 25m where sunlight can penetrate. Water must also be clear and clean for photosynthesis.
* Salinity- Corals need salty water to survive: 32%-42% salt water.
35
# Coastal Ecosystems around the world.
Explain the distribution of Mangroves:
Found in warm tropical waters and coastal swamps within 30N and 30S of the equator.
Grow in the intertidal zone of the coast.
36
# Coastal Ecosystems around the world.
What are the features of Mangroves?
* Water- Need shallow water between 0.5m to 2.5m high
* Humidity- High levels of humidity required (75%-80%)
* Rain- Need (1500-3000mm) rainfall per annum.
* Temperature- Ideal temp required is 27 degrees Celsius.
37
# Coastal Ecosystems around the world.
Explain the distrbutions of Sand Dunes
Coastal sand dunes are found all over the world.
38
# Coastal Ecosystems around the world.
What are the features of sand dunes?
* Vulnerable to erosion by natural processes and human activity.
* Can extend backward for many miles as well as along the beach
39
# Characteristics of Coastal Ecosystems
What is an ecosystem?
A community of interacting biotic and abiotic organisms.
40
# Characteristics of Coastal Ecosystems
What 3 stores do all ecosystems survive by nutrient cycling?
* Biomass
* Litter
* Seawater
41
# Characteristics of Coastal Ecosystems
What are the biotic components of a Coral Reef?
* **Producers:** seaweed, seagrass and phtoplankton.
* **Consumers:** primary: green sea turtles secondary: octopuses tertiary: sharks
* **Scavengers:**Crabs and lobsters.
* **Decomposers:** Bacteria, fungi
42
# Characteristics of Coastal Ecosystems
What are the abiotic features of a coral reef?
* **Sunlight:** Corals need some sunlight to survive-for photosynthesis.
* **Depth:** As corals need light, typically corals can be found at 25m under sea level.
* **Water Temps:** Prefer temperatures of 23-29 degrees Celsius
* **Salinity:** Corals need salty water (32%-42%)
* **Air:** Can survive out of water for very short periods of time.
* **Water:** Need clean and clear water.
43
# Threats to Coastal Ecosystems
Give examples of goods provided by coastal ecosystems:
* Fish
* Seaweed for: Food, Medicines, Industrial Use
* Animal Feed
* Land
* Construction Materials
44
# Threats to Coastal Ecosystems
Give examples of services provided by coastal ecosystems:
* Protection from: storms, coastal flooding
* Natural shelters.
* Natural waste treatment
* Biodiversity
* Leisure
45
# Threats to Coastal Ecosystems
What are the different threats to coastal ecosystems such as mangroves and coral reefs?
* Industrial Threats
* Agricultural Practices
* Tourism
* Deforestation
46
# Threats to Coastal Ecosystems
What are some industrial threats to coral reefs?
* Pollution, overfishing and quarrying of coral for building stone.
* Rising sea temps and rise in sea levels (rising tempscauses coral bleaching)
* Coral reefs overstressing from human activities can lead to death.
47
# Threats to Coastal Ecosystems
What are the threats to coral reefs from agricultural practices?
* Fishing using explosives
* Pesticide overspraying
* Commerical farming
48
# Threats to Coastal Ecosystems
What are threats to coral reefs from tourism?
* Biggest threat globally and locally to coral reefs
* Any contact with human body likely to kill coral immediately
* Propellers and anchors from boat tours.
49
# Threats to Coastal Ecosystems
What are threats to coral reefs from deforestation?
* Clearance of coastal forests or mangroves disturbs natural flows of water and nutrients leading to stress and coral bleaching.
* Removal of coral for stone building.
50
# Threats to Coastal Ecosystems
What are the industrial threats to mangroves?
* Pollution, overfishing and deforestation for aquaculture.
* Clearance for land development
51
# Threats to Coastal Ecosystems
What are the threats to mangroves from agricultural practices?
* Aquaculture- intense fish and shrimp farms
* Pesticide use
* Clearance for farm development
52
# Threats to Coastal Ecosystems
What are the threats to mangroves from tourism?
* Clearance of mangroves for hotels and other tourist locations (resorts)
* Diversion of fresh water to hotels
* Collection of souvenirs by tourists
* Disturbance of habitats.
53
# Threats to Coastal Ecosystems
What are the threats to mangroves from deforestation?
* Removal of trees leads to collapse of ecosystem.
* Leaves coast open to coastal flooding
* Mangrove wood is used for timber and fuel.
54
# Conflcit at the Coast
What are the different variety of purposes that coastal environments are useful for?
* Development
* Fishing
* Industry
* Agriculture
* Tourism
55
# Conflcit at the Coast
What is another way of saying "conflict between coastal users"?
Conflicts between stakeholders.
56
# Conflcit at the Coast
What are some examples of stakeholders and their wants?
* Wildlife want unpolluted, safe environment
* Local residents want jobs, clean beaches, affordable housing
* Tourists want beaches, hotels
* Developers want areas by the sea for tourists.
57
# Causes of Coastal Flooding
What are some natural causes of coastal flooding?
* Storm surges- rapid rise in sea level caused by low-pressure storms.
* Storm Tides- Occur when there is a combination of high tide and low-pressure storm.
* Tsunamis- Large sea waves due to underwater earthquakes.
58
# Causes of Coastal Flooding
Explain 2 methods used to help forecast coastal flooding:
1. Past records: Will identify areas at high risk and frequency.
2. Modern Technology: GIS, satellite and computer monitoring.
59
# Causes of Coastal Flooding
Explain actions that reduces or removes the risk of coastal flooding:
* Flood defences
* Emergency centres
* Early warning systems
* Education
* Planning
* Buffer zones.
60
# Coastal Management Strategies
What is a Shoreline Management Plan (SMP) and what does it aim to do?
* SMPS set out an approach to managing a coastline from flooding and erosional risks.
* The plan aims to reduce risk to people, settlements, agricultural lands and natural environments.
61
# Coastal Management Strategies
What are 4 approaches available for coastline management?
* Hold the line- hard engineering dominant
* Advance the Line- soft and hard engineering used
* Managed reallignment- soft engineering dominant
* Do nothing
62
# Coastal Management Strategies
What do decisions about approaches on coastal management depend on?
* Economic value of resources that would be protected.
* Engineering solutions- Might not be possible to 'hold the line'for moving landforms.
* Community Pressure
63
# Coastal Management Strategies
When is hard engineering mainly used?
When settlements or expensive installments are at risk.
64
# Coastal Management Strategies
Describe beach replenishment
Pumping or dumping sand or shingle back onto a beach.
65
# Coastal Management Strategies
What are the advantages and disadvantages of beach replenishment?
* Advantages:
Beaches absorb wave energy
Widens beach front
* Disadvantages:
Has to be repeated regularly- which is expensive
Can impact sediment transportation down the coast.
66
# Coastal Management Strategies
Describe cliff regrading
Angle of cliff reduced to reduce mass movement.
67
# Coastal Management Strategies
What are the advantages and disadvantages of cliff regrading?
* Advantages:
Prevents sudden loss of large sections of the cliff.
Slow down wave cut notching
* Disadvantages:
Does not stop cliff erosion
68
# Coastal Management Strategies
Describe managed retreat
Existing coastal defences are abandoned allowing the sea to flood inland until it reaches higher land or a new line of sea defences.
69
# Coastal Management Strategies
What are the advantages and disadvantages of managed retreat?
* Advantages:
No expensive construction costs
Creates new habitats such as salt marshes
* Disadvantages:
People's lands and homes are lost.
Cost of relocation may be expensive
70
# Coastal Management Strategies
Define ecosystem rehabilitation and revegetation
Helps to stabilize sand dunes or beaches
Reduces wind erosion
71
# Coastal Management Strategies
What are the Advantages and Disadvantages of ecosystem rehabilitation and revegatation:
* Advantages: Cheap method
* Disadvantages: Hard to protect larger areas of coastline cliffs.
72
# Coastal Management Strategies
Describe groynes:
Wood,rock or steel piling built at right angles to shore- traps sediment from longshore drift.
73
# Coastal Management Strategies
What are the Advantages and Disadvantages of groynes?
* Advantages:
Slows down beach erosion
Creates wider beaches
* Disadvantages:
Stops material from going elsewhere
Starves other beaches of sand
Hard to walk along shoreline.
74
# Coastal Management Strategies
Describe revetments
Sloping wooden or concrete fence with open plank structure.
75
# Coastal Management Strategies
What are the Advantages and Disadvantages of revetments?
* Advantages:
Traps beach material behind them.
Cheaper than sea walls
* Disadvantages:
Can make beach inaccessible
Visually unnattractive
Regular maintenance required
76
# Coastal Management Strategies
Describe sea walls
A wall, usually concrete and curved outwards to deflect the power of waves.
77
# Coastal Management Strategies
What are the Advantages and Disadvantages of sea walls?
* Advantages:
Most effective at preventing both flooding and erosion.
* Disadvantages:
Very expensive to build and mantain
Unslightly to look at.
78
# Coastal Management Strategies
Describe gabions
Wire cages filled with stone, concrete, sand etc.
79
# Coastal Management Strategies
What are the Advantages and Disadvantages of gabions?
* Advantages:
Cheapest form of coastal defence
Cages absorb wave energy.
* Disadvantages:
Wire cages can break
Not as efficient as other coastal defences
80
# Coastal Management Strategies
Describe rip raps
Large boulders are piled up to protect a stretch of the coast.
81
# Coastal Management Strategies
What are the Advantages and Disadvantages of rip raps?
* Advantages:
Cheap method of construction
Works to absorb wave energy from base of cliff.
* Disadvantages:
Boulders can be eroded or dislodged during heavy storms.
