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A Level geog > Coasts > Flashcards

Coasts Flashcards

1
Q

Systems

A

Open systems, energy and matter

Closed system, energy

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2
Q

Is the coast an open or closed system?

A

Open system

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3
Q

Inputs in a coastal system

A

Energy from; tides, waves, wind, currents

Sun

Air Pressure

Sediment

Pollution

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4
Q

Outputs in a coastal system

A

Sediment

Ocean Currents

Rip Tides

Evaporation

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5
Q

Processess in a coastal system

A

Erosion

Deposition

Longshore drift

Transportation

Weathering

Mass Movement

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6
Q

How many sediment cells are around the UK

A

11

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7
Q

What is dynamic equilibrium

A

Balance in a natural system while being in a constant state of change

A balance between inputs and outputs

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8
Q

Why may the equilibrium be distrupted

A

long term - human activity

short term - natural variations e.g seasons or hazard events

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9
Q

What are the stores in the coastal system

A

Beaches

Landforms

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10
Q

Where does the coastal system gain energy?

A

Through winds, gravity and flowing water

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11
Q

What are the feedback loops

A

positive - exacerbates a change

negative - reduces a change to return to dynamic equilibrium

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12
Q

What are the primary sources of sediment

A

Rivers

Cliff erosion

Wind

Glaciers

Longshore drift

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13
Q

Define the littoral zone

A

Area between the cliffs or dunes and the offshore zone beyone the influence of the waves, constantly changing

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14
Q

Explain Wave formation

A

Wind moves across surface causing frictional drag which creates small ripples and waves and an elliptical movement of the water, the waves become larger as they near the coast as the water becomes shallower

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15
Q

What are the factors affecting wave energy

A

Strength and duration of the wind

Size of the fetch

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16
Q

What are the two wave types

A

constructive

Destructive

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17
Q

Tides

A

Highest high tides and lowest low tides occur when sun and moon aer in alignment -called a ‘spring tide’, it has the highest possible tidal range and occurs due to gravity

Lowest high tide and highest low tides occur when sun and moon are perpendicular - this is known as a neap tide, and has the lowest possible tidal range

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18
Q

Currents

A

Rip currents are powerful underwater currents occurring in areas close to the shoreline on some beaches when plunging waves cause a buildup of water at the top of the beach

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19
Q

High-energy coastlines

A

High-energy coastlines are associated with more powerful waves, so occur in areas where there is a large fetch. They typically have rocky headlands and landforms and fairly frequent destructive waves. As a result these coastlines are often eroding as the rate of erosion exceeds the rate of deposition

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20
Q

Low-energy coastlines

A

Low-energy coastlines have less powerful waves and occur in sheltered areas where
constructive waves prevail and as a result these are often fairly sandy areas. There are
landforms of deposition as the rates of deposition exceed the rates of erosion

21
Q

Wave refraction

A

Wave refraction is the process by which waves turn and lose energy around a headland on uneven coastlines. The wave energy is focused on the headlands , creating erosive features in these areas. The energy is dissipated in bays leading to the formation of features associated with lower energy environments such as beaches.

22
Q

Types of Erosion

A

Corrasion - Sand and particles are hurled against the side of a cliff at high tide

Abrasion - Sediment is moved along a shoreline causing it to be weakened over time

Attrition - Rocks bounce against eack other

Hydraulic action - air is forced into cracks, joints and faults, high pressure causes mini explosions

Solution - doses of carbonic acid cause the rocks to break down

23
Q

Factors affecting erosion

A

Waves
Beaches
Sub Aerial processes
Rock Type

24
Q

Processes of Transportation

A

Traction - Large particles are rolled along the sea bed

Saltation - Rocks bounce along sea bed

Suspension - particles are suspended in sea water

Solution - Rocks are dissolved

25
Q

Longshore drift

A

Waves hit beach at an angle determined by wind before leaving carrying sediment along a coastline

26
Q

What are the types of weathering

A

Weathering happens in situ

Chemical e.g Carbonation
Biological e.g burrowing
Physical e.g freeze thaw

27
Q

Mass movement

A

Movement of material down a slope under the influence of gravity

28
Q

What are the types of mass movement

A

Soil Creep - Slowest type, soild moves down a slope due to wetting and drying

Mudflows- High water content in soil, water gets trapped in rocks causing a build up of pressure, can be fast flowing

Landslide

Slump - Curved ground, land collapses under its own weight

Runoff

29
Q

Types of Erosional landform

A

Cave, Arch, Stack, Stump

Wave-cut platform - erosion focused at high tide mark, over time form notch, over time form platform exposed at high-tide

Headlands and Bays

30
Q

Types of Depositional Landforms

A

Beaches

Spits

Bars - spit joins 2 headlands, if it becomes detatches from headland it forms a barrier beach

Tombolo - Spit connects mainland to offshore island due to wave refraction

Offshore bar

31
Q

Sand Dune Development

A

Embryo Dunes – Upper beach area where sand starts to accumulate around a small
obstacle (driftwood, wooden peg, ridge of shingle)
● Yellow Dunes – As more sand accumulates and the dune growns, vegetation may develop
on the upper and back dune surfaces, which stabilises the dune. The tallest of the dune
succession
● Grey Dunes – Sand develops into soil with lots of moisture and nutrients, as vegetation
dies, enabling more varied plant growth
● Dune Slack – The water table rises closer to the surface, or water is trapped between
hollows between dunes during storms, allowing the development of moisture-loving plants

32
Q

Mudflats and Salt Marsh

A

Deposition occurs in river estuaries because when the flow of water from the river meets with the incoming tides and waves from the sea, causing water flow to virtually cease , so the water can no longer carry its sediment in suspension. They may also occur in sheltered areas such as behind a spit or other areas where there are no strong tides or currents to prevent sediment deposition and accumulation.

As most of the sediment is small, this leads to a build up of mud , which over time builds up until itis above the water level. Pioneer plants colonisethis area, leading to more sediment becoming trapped.

33
Q

Isostatic Change

A

Isolated incident, land rises or falls relative ot the sea, can happen due to glaciers melting causing the continent to rebound.

Also impacted by tectonic activity as seen at Tohoku which dropped 60cm

Emergent landforms - land raised in relation to the coast e.g raised beaches

34
Q

Eustatic Change

A

Sea level change, happens everywhere

Submergent landforms - sea level rises or coastline sinks e.g rias or fjords

35
Q

Dalmatian Coasts

A

Valleys running parallel to the coast become flooded leaving a series of long narrow islands

36
Q

Risks to coastal environments

A

Storm Surges

Climate Change

Human Activity

37
Q

Why has Coastal Mangement Changed?

A

New research on the risks and benefits

38
Q

Hard Engineering

A

Man-made structures attempt to prevent erosion, they are ofter useful but are largely harmful to the environment and costly.

They may exacerbate erosion elsewhere

39
Q

Examples of Hard Engineering

A

Groynes - Long fences that prevent LSD by trapping sediment.

Pro - Builds up beach and protects cliffs, Cost effective

Cons - Deprive areas from sediment

Sea Walls - Concrete Structures that absorb wave energy

Pros - prevent erosion

Cons - Costly to maintain, made of concrete

40
Q

Examples of Hard Engineering

A

Rip Rap - Large rocks that absorb wave energy while allowing water to flow through

Pros - Cost Effective

Cons - Rocks sourced elsewhere so look out of place, hazard if climbed

Revetments - Wooden or concrete ramps that absorb wave energy

Pros - Cost Effective

Cons - Need constant maintainance

41
Q

Soft Engineering

A

Aims to work with the natural environment in order to protect the coast, aim to combat sea level change also

42
Q

Examples of Soft Engineering

A

Beach Nourishment - Sediment taken form offshore sources to build up the beach

Pros - Looks natural, builds up beach

Cons - Needs constant maintainance

Cliff Regrading and Drainage - Reduce the angle of a cliff to help stabalise it

Pros - Cost Effective

Cons - Cliff may suddenly collapse due to added rock, may look unnatural

43
Q

Cost Benefit Analysis

A

Analysis carried out before any management, benefits must outweigh costs

44
Q

Integrated Coastal Zone Management (ICZM)

A

Created in the 1990’s, recognises the coasts value for everyday life and theorises that while economic benefit is important the livelihood of the coast is more so

45
Q

Shoreline Management Plans (SMP)

A

For each cell a SMP is devised

● Hold the Line: Defences are used to maintain the current position of the shoreline

● Managed Realignment/Retreat: Defences and engineering techniques are used to allow
the coastline to advance inland and create its own natural defences such as salt marshes

● Advance the Line : Defence are built to try and move the shoreline seawards, potentially to protect an important population centre or tourist amenity

● No Active Intervention: The coastline is exposed to natural processes

46
Q

Holderness Coast

A
  • Erodes by 2m a year, one of the fastest eroding coastlines
  • From Flamborough in the North to Spurn Point in South
  • Covered in soft boulder clay which is why it erodes so fast

The exposed chalk of Flamborough provides examples of erosion, features such as caves, arches and stacks. Coastal management at Hornsea and Withernsea are examples of hard engineering solutions to coastal erosion. Erosion at Skipsea illustrates the human impact of erosion in areas where coastlines are not being defended. Mappleton is an excellent case study of an attempt at coastal management which has a negative impact further along the coast.

  • East Coast of England
47
Q

Kiribati

A
  • South Pacific Ocean
  • 2m on average above sea level
  • Erodes by 1.2 m a year
  • 100000 population with 60% under 30
  • PLanted 50000 mangroves

-Many have moved to Fiji

  • Freshwater contaminated by sea water
  • Expected to not exist by 2100
48
Q

Formation of a Tombolo

A

Formed through wave refraction and defraction. As waves approach bay they have lost energy so they begin to deposit sediment, this is exacerbated as they approach islands, sediment builds up over time to connect the island with the mainland

49
Q

Formation of an offshore bar

A

Ridges of sand or shingle running parallel to the coast in an offshore zone

Sediment is deposited at the boundary of the littoral zone

Usually submerged

Can be formed when waves break early

A Level geog (6 decks)

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