CONTENTS FOR COASTAL ENVIRONMENTS
8.1 Coastal Processes .............................................................................................................................. 5
The littoral/coastal zone .................................................................................................................... 5
Factors influencing coasts .................................................................................................................. 5
Dynamic equilibrium .......................................................................................................................... 6
Factors affecting coasts ...................................................................................................................... 7
How the coast is shaped by wave action........................................................................................... 7
Wave construction ............................................................................................................................. 7
Tides & Tidal cycles ............................................................................................................................ 9
Tidal frequency ............................................................................................................................... 9
Tidal range....................................................................................................................................... 9
Tidal Bore ........................................................................................................................................ 9
Amphidromic points......................................................................................................................... 10
Storm Surges..................................................................................................................................... 11
Factors affecting the nature of the storm surge ........................................................................... 11
UK Storm Surge, 1953 ................................................................................................................... 11
Waves of Transition ......................................................................................................................... 12
Types of breakers .......................................................................................................................... 12
Constructive and Destructive waves ............................................................................................... 13
Processes and landforms relating to waves .................................................................................... 13
Wave refraction ................................................................................................................................ 15
Wave diffraction ............................................................................................................................... 16
Wave action ...................................................................................................................................... 16
Coastal erosion - marine processes ................................................................................................. 17
1. Hydraulic action .................................................................................................................... 17
2. Abrasion/corrasion ............................................................................................................... 17
3. Attrition ................................................................................................................................. 17
4. Solution/corrosion ................................................................................................................ 17
5. Cavitation (part of hydraulic action) ..................................................................................... 17
6. Sub aerial processes (weathering/mass movement) ............................................................ 17
Mass movement ............................................................................................................................... 18
➔ Landslides .......................................................................................................................... 18
➔ Soil creep ........................................................................................................................... 18
➔ Mud flows ......................................................................................................................... 18
➔ Slumping............................................................................................................................ 18
1
, ➔ Rock falls ........................................................................................................................... 18
Weathering ....................................................................................................................................... 19
Biological weathering.................................................................................................................... 19
Physical weathering ...................................................................................................................... 19
Chemical weathering .................................................................................................................... 19
Influences on coastal landscape systems ........................................................................................ 19
1. Lithology................................................................................................................................ 19
2. Structure ............................................................................................................................... 19
How geology affects cliff erosion..................................................................................................... 21
Sedimentary .................................................................................................................................. 21
Igneous .......................................................................................................................................... 21
Unconsolidated ............................................................................................................................. 21
Transportation – The Load ............................................................................................................... 22
Debris formation ............................................................................................................................... 22
Sediment moved by water ................................................................................................................ 22
3 types of sediment transport ......................................................................................................... 22
1) Bedload ................................................................................................................................. 22
2) Suspended load ..................................................................................................................... 22
3) Wash load ............................................................................................................................. 22
Transportation processes................................................................................................................. 22
• Traction ................................................................................................................................. 22
• Saltation ................................................................................................................................ 22
• Suspension ............................................................................................................................ 22
• Solution ................................................................................................................................. 22
On shore and off shore transportation ........................................................................................... 23
Longshore drift ................................................................................................................................. 23
Marine deposition ............................................................................................................................ 23
Sediment cells................................................................................................................................... 24
Introduction to coral reefs ............................................................................................................... 26
What do corals need to grow? ...................................................................................................... 27
Types of reef and how they develop (Darwin’s theory) ............................................................... 28
Subsidence theory of Darwin overview 1842.............................................................................. 29
Glacial Control theory of Daly 1915 ............................................................................................. 30
Stand still theory of Murry 1880 .................................................................................................. 30
The value of coral reefs .................................................................................................................... 31
2
, Threats to coral reefs ....................................................................................................................... 33
Local threats to coral reefs............................................................................................................... 35
Global threats ................................................................................................................................... 35
Coral bleaching ................................................................................................................................. 36
Management of coral reefs .............................................................................................................. 37
Difference between adaptation and mitigation ............................................................................. 37
Strategies to reduce global warming (mitigation) .......................................................................... 38
Managing the Great Barrier Reef..................................................................................................... 40
Limiting factors on coral reef development .................................................................................... 42
Natural causes of reef decline ......................................................................................................... 43
Human impacts on reefs .................................................................................................................. 43
Management strategies ................................................................................................................... 43
Strategies for the successful development of marine protected areas........................................ 43
8.2 Characteristics and formation of coastal landforms ...................................................................... 45
EROSIONAL LANDFORMS ................................................................................................................. 45
Cliffs – most dominant feature of erosion: ................................................................................. 45
Wave cut notch: ........................................................................................................................... 45
Headlands and bays: .................................................................................................................... 46
Crack → cave → arch → stack → stump: .................................................................................... 46
Blow hole: ..................................................................................................................................... 47
The Pembrokeshire Coast (South West Wales) : Coastal Erosion Case Study ............................... 48
DEPOSITIONAL LANDFORMS............................................................................................................ 53
Beaches: ........................................................................................................................................ 53
Spits: ............................................................................................................................................. 55
Bars: .............................................................................................................................................. 56
Tombolo’s: .................................................................................................................................... 56
Barrier beaches:............................................................................................................................ 57
Barrier islands and offshore bars:................................................................................................ 57
Salt Marshes: ................................................................................................................................ 58
Plant succession ............................................................................................................................... 58
Succession in a salt marsh............................................................................................................. 59
Mangroves (tropical version of a salt marsh) :............................................................................ 60
Sea level change on features ........................................................................................................... 61
Features created by sea level change: ......................................................................................... 61
Impacts of present and predicted sea level rise ............................................................................. 62
8.4 Coastal management ..................................................................................................................... 63
3
,Environmental sustainability: Considers conserving the coastal system (cell), reducing or
preventing pollution, maintaining the aesthetics of the coastline Economic sustainability: ......... 63
Social sustainability: ......................................................................................................................... 63
Sustainable management: ............................................................................................................... 63
Stakeholders ..................................................................................................................................... 63
Strategies for coastal management ................................................................................................. 63
Protection methods – soft engineering ........................................................................................... 64
Protection methods – hard engineering.......................................................................................... 64
4
, COASTAL ENVIRONMENTS
8.1 Coastal Processes
The littoral/coastal zone:
➢ The zone of transition (the boundary) between the land & sea. It is a dynamic zone
meaning it’s constantly changing.
➢ It is affected by many processes, we are focusing mainly on beaches
➢ The zone adjusts to a series of physical processes such as wave energy and winds.
1) Land – 2) Humans – 3) Atmospheric factors – 4) Marine –
• Geology • Tourism & recreation • Climate • Tides
• Tectonics • Pollution • Global warming • Deposition
• • Solar energy • Salt
• Biotic features Sea defences
• Building • Weathering • Biotic features
• Gravity
• Conservation • Waves and tsunami’s
•
Biotic features = living
Factors influencing coasts: things in an ecosystem e.g.
plants, animals & fungi
Others in more depth:
Rock type (lithology)
- Hard rocks e.g. granite and basalt create rugged landscapes such as the Giants
Causeway in Northern Ireland
- Whereas soft rocks e.g. sands and gravels produce low, flat landscapes such as the
Nile delta area
Geological structure
- Concordant (Pacific) coastlines occur where geological strata lie parallel to the
coastline e.g. Pacific Coat of the USA
- Whereas discordant (Atlantic) coastlines occur where geological strata are at right
angles to the shoreline e.g. South West Coast of Ireland
Processes
- Erosional landscapes e.g. East Coast of England contain many rapidly retreating cliffs
- Whereas areas of rapid deposition e.g. Netherlands, contain many sand dunes and
coastal flats
Sea level changes
- Interaction with erosional and depositional processes produce changes in coasts
- For example, growing coastlines are due to deposition and/or a fall in sea level
whereas retreating coasts are due to erosion and/or a rise in sea level
5
8.1 Coastal Processes .............................................................................................................................. 5
The littoral/coastal zone .................................................................................................................... 5
Factors influencing coasts .................................................................................................................. 5
Dynamic equilibrium .......................................................................................................................... 6
Factors affecting coasts ...................................................................................................................... 7
How the coast is shaped by wave action........................................................................................... 7
Wave construction ............................................................................................................................. 7
Tides & Tidal cycles ............................................................................................................................ 9
Tidal frequency ............................................................................................................................... 9
Tidal range....................................................................................................................................... 9
Tidal Bore ........................................................................................................................................ 9
Amphidromic points......................................................................................................................... 10
Storm Surges..................................................................................................................................... 11
Factors affecting the nature of the storm surge ........................................................................... 11
UK Storm Surge, 1953 ................................................................................................................... 11
Waves of Transition ......................................................................................................................... 12
Types of breakers .......................................................................................................................... 12
Constructive and Destructive waves ............................................................................................... 13
Processes and landforms relating to waves .................................................................................... 13
Wave refraction ................................................................................................................................ 15
Wave diffraction ............................................................................................................................... 16
Wave action ...................................................................................................................................... 16
Coastal erosion - marine processes ................................................................................................. 17
1. Hydraulic action .................................................................................................................... 17
2. Abrasion/corrasion ............................................................................................................... 17
3. Attrition ................................................................................................................................. 17
4. Solution/corrosion ................................................................................................................ 17
5. Cavitation (part of hydraulic action) ..................................................................................... 17
6. Sub aerial processes (weathering/mass movement) ............................................................ 17
Mass movement ............................................................................................................................... 18
➔ Landslides .......................................................................................................................... 18
➔ Soil creep ........................................................................................................................... 18
➔ Mud flows ......................................................................................................................... 18
➔ Slumping............................................................................................................................ 18
1
, ➔ Rock falls ........................................................................................................................... 18
Weathering ....................................................................................................................................... 19
Biological weathering.................................................................................................................... 19
Physical weathering ...................................................................................................................... 19
Chemical weathering .................................................................................................................... 19
Influences on coastal landscape systems ........................................................................................ 19
1. Lithology................................................................................................................................ 19
2. Structure ............................................................................................................................... 19
How geology affects cliff erosion..................................................................................................... 21
Sedimentary .................................................................................................................................. 21
Igneous .......................................................................................................................................... 21
Unconsolidated ............................................................................................................................. 21
Transportation – The Load ............................................................................................................... 22
Debris formation ............................................................................................................................... 22
Sediment moved by water ................................................................................................................ 22
3 types of sediment transport ......................................................................................................... 22
1) Bedload ................................................................................................................................. 22
2) Suspended load ..................................................................................................................... 22
3) Wash load ............................................................................................................................. 22
Transportation processes................................................................................................................. 22
• Traction ................................................................................................................................. 22
• Saltation ................................................................................................................................ 22
• Suspension ............................................................................................................................ 22
• Solution ................................................................................................................................. 22
On shore and off shore transportation ........................................................................................... 23
Longshore drift ................................................................................................................................. 23
Marine deposition ............................................................................................................................ 23
Sediment cells................................................................................................................................... 24
Introduction to coral reefs ............................................................................................................... 26
What do corals need to grow? ...................................................................................................... 27
Types of reef and how they develop (Darwin’s theory) ............................................................... 28
Subsidence theory of Darwin overview 1842.............................................................................. 29
Glacial Control theory of Daly 1915 ............................................................................................. 30
Stand still theory of Murry 1880 .................................................................................................. 30
The value of coral reefs .................................................................................................................... 31
2
, Threats to coral reefs ....................................................................................................................... 33
Local threats to coral reefs............................................................................................................... 35
Global threats ................................................................................................................................... 35
Coral bleaching ................................................................................................................................. 36
Management of coral reefs .............................................................................................................. 37
Difference between adaptation and mitigation ............................................................................. 37
Strategies to reduce global warming (mitigation) .......................................................................... 38
Managing the Great Barrier Reef..................................................................................................... 40
Limiting factors on coral reef development .................................................................................... 42
Natural causes of reef decline ......................................................................................................... 43
Human impacts on reefs .................................................................................................................. 43
Management strategies ................................................................................................................... 43
Strategies for the successful development of marine protected areas........................................ 43
8.2 Characteristics and formation of coastal landforms ...................................................................... 45
EROSIONAL LANDFORMS ................................................................................................................. 45
Cliffs – most dominant feature of erosion: ................................................................................. 45
Wave cut notch: ........................................................................................................................... 45
Headlands and bays: .................................................................................................................... 46
Crack → cave → arch → stack → stump: .................................................................................... 46
Blow hole: ..................................................................................................................................... 47
The Pembrokeshire Coast (South West Wales) : Coastal Erosion Case Study ............................... 48
DEPOSITIONAL LANDFORMS............................................................................................................ 53
Beaches: ........................................................................................................................................ 53
Spits: ............................................................................................................................................. 55
Bars: .............................................................................................................................................. 56
Tombolo’s: .................................................................................................................................... 56
Barrier beaches:............................................................................................................................ 57
Barrier islands and offshore bars:................................................................................................ 57
Salt Marshes: ................................................................................................................................ 58
Plant succession ............................................................................................................................... 58
Succession in a salt marsh............................................................................................................. 59
Mangroves (tropical version of a salt marsh) :............................................................................ 60
Sea level change on features ........................................................................................................... 61
Features created by sea level change: ......................................................................................... 61
Impacts of present and predicted sea level rise ............................................................................. 62
8.4 Coastal management ..................................................................................................................... 63
3
,Environmental sustainability: Considers conserving the coastal system (cell), reducing or
preventing pollution, maintaining the aesthetics of the coastline Economic sustainability: ......... 63
Social sustainability: ......................................................................................................................... 63
Sustainable management: ............................................................................................................... 63
Stakeholders ..................................................................................................................................... 63
Strategies for coastal management ................................................................................................. 63
Protection methods – soft engineering ........................................................................................... 64
Protection methods – hard engineering.......................................................................................... 64
4
, COASTAL ENVIRONMENTS
8.1 Coastal Processes
The littoral/coastal zone:
➢ The zone of transition (the boundary) between the land & sea. It is a dynamic zone
meaning it’s constantly changing.
➢ It is affected by many processes, we are focusing mainly on beaches
➢ The zone adjusts to a series of physical processes such as wave energy and winds.
1) Land – 2) Humans – 3) Atmospheric factors – 4) Marine –
• Geology • Tourism & recreation • Climate • Tides
• Tectonics • Pollution • Global warming • Deposition
• • Solar energy • Salt
• Biotic features Sea defences
• Building • Weathering • Biotic features
• Gravity
• Conservation • Waves and tsunami’s
•
Biotic features = living
Factors influencing coasts: things in an ecosystem e.g.
plants, animals & fungi
Others in more depth:
Rock type (lithology)
- Hard rocks e.g. granite and basalt create rugged landscapes such as the Giants
Causeway in Northern Ireland
- Whereas soft rocks e.g. sands and gravels produce low, flat landscapes such as the
Nile delta area
Geological structure
- Concordant (Pacific) coastlines occur where geological strata lie parallel to the
coastline e.g. Pacific Coat of the USA
- Whereas discordant (Atlantic) coastlines occur where geological strata are at right
angles to the shoreline e.g. South West Coast of Ireland
Processes
- Erosional landscapes e.g. East Coast of England contain many rapidly retreating cliffs
- Whereas areas of rapid deposition e.g. Netherlands, contain many sand dunes and
coastal flats
Sea level changes
- Interaction with erosional and depositional processes produce changes in coasts
- For example, growing coastlines are due to deposition and/or a fall in sea level
whereas retreating coasts are due to erosion and/or a rise in sea level
5
