1.1 Landscape systems - Coasts
04 September 2024 18:19
Glossary
Term Definition
Orthogonal Wave crest
Cusp Hollow semi-circular depression on a beach
Horn Protruding areas of material on a beach
Percolation Movement of water through rock (do not use infiltrate)
Continental shelf Large submerged area of seabed attached to the mainland
Halosere Salt marsh ecosystem
Halophytic plant Salt-tolerant plant
Alluvium Mud
Anthropogenic Caused by humans (e.g. anthropogenic climate change)
Estuarine Of or found in the (possibly tidal) mouths of large rivers
Carrying capacity How much sediment a river can carry
Abrasion (corrasion) Erosion caused when rocks carried by waves are thrown against a cliff
Attrition Rocks carried by waves collide and become smaller and more rounded
Hydraulic action Air trapped in cracks is compressed by waves, causing rock to break
Solution (corrosion) Chemical erosion where acidic seawater dissolves rock (e.g. limestone)
Longshore drift Movement of sediment along the coast by angled waves
Swash Movement of water up the beach at an angle
Backwash Movement of water back down the beach at 90° to the shoreline
Constructive waves Low-energy waves that deposit sediment and build beaches
Destructive waves High-energy waves that remove sediment and erode beaches
Fetch Distance of open water over which the wind blows to form waves
Wave refraction Bending of waves as they enter shallow water, focusing energy on headlands
Headland Resistant rock sticking out into the sea
Bay Area of softer rock eroded more quickly between headlands
Cave Hollow formed by erosion at the base of a cliff
Arch Cave eroded through a headland
Stack Isolated pillar of rock left after an arch collapses
Stump Eroded remains of a stack, visible at low tide
Beach profile Cross-section of a beach showing shape and slope
Berm Ridge of sediment at the top of a beach formed by constructive waves
Spit Narrow ridge of sand or shingle attached at one end, formed by longshore drift
Bar Spit that extends across a bay, cutting it off from the sea
Tombolo Spit connecting the mainland to an island
Salt marsh Low-energy coastal ecosystem that develops behind spits
Pioneer species First plants to colonise bare mud (e.g. glasswort)
Succession Gradual change in plant communities over time
coasts Page 1
,Succession Gradual change in plant communities over time
Hard engineering Man-made coastal defences that resist natural processes
Soft engineering Management that works with natural processes
Groynes Barriers that trap sediment moved by longshore drift
Sea wall Concrete barrier that reflects wave energy
Rock armour (rip-rap) Large boulders placed at the base of cliffs to absorb wave energy
Managed retreat Allowing low-value land to flood naturally to reduce risk elsewhere
coasts Page 2
,① Coastal Landscapes as a System
15 October 2024 11:10
A geographical system is a group of objects and the relationships between them. They store and transfer energy and material on time scales that can vary from a few days to
millennia
Coastal landscapes are recognised as open systems because a) energy and matter can be transferred from neighbouring systems as an input b) energy and matter can be transferred
to neighbouring systems as an output
Inputs
↙ ↓ ↘
Processes Stores Flows
↘ ↓ ↙
Outputs
The energy available to coastal landscapes may be kinetic, potential (GPE) or thermal
SEDIMENT CELLS
• Sediment movement occurs in distinct areas called cells
• Cells are a stretch of coastline within which the movement of sediment, sand and shingle is largely self-contained
• A sediment cell is a stretch of coastline and its associated nearshore area within which the movement of coarse sediment, san d and shingle is largely self-contained
• If part of a larger cell, they are called sub-cells
• Sediment cells are considered to be a closed system as the sediment stays largely within the cell - however in reality it is unlikely that sediment cells are completely closed
Throughputs/flows
Inputs → Components → Components → Outputs
Erosional processes Wind and water transport Wind and water transport
Energy from Erosional landforms Depositional landforms Dissipation of wave energy
• Wind
• Waves
• Tides
• Currents
Sediment Accumulation of sediment above the
tidal limit
Geology Sediment removed beyond local
sediment cells
Sea level
Equilibrium
Where there is a balance within a (coastal) system
Such as when inputs of energy and matter into that system and outputs of energy and matter out of that (coastal) system are t he same
Dynamic equilibrium
Natural systems are rarely in a constant state of static equilibrium as systems are always disturbed, with amplifications or reduction in inputs or energy and matter, or they may be
influenced by some external factor such as human activity
Therefore, they often self-regulate and produce their own response to such events through negative feedback mechanisms
Negative feedback
When a system self regulates to restore order and balance
coasts Page 3
, ② Factors Influencing Coastal
Landscapes
15 October 2024 15:12
Marine processes
Process Types / Examples
Erosion Hydraulic action, abrasion (corrasion), attrition, solution
Transportation Longshore drift
Deposition Occurs when wave energy decreases
Weathering processes
Type Processes
Biological Chelation, plant roots, marine organisms
Mechanical (physical) Freeze–thaw, pressure release, salt crystallisation
Chemical Carbonation, solution, oxidation, hydration, hydrolysis
Mass movement processes
Type Description
Falls Sudden movement of material from steep slopes or cliffs
Slides (linear and rotational) Movement of material along a slip plane
Fluvial processes
Process Description
Erosion Wearing away of river bed and banks
Transportation Movement of sediment by a river
Deposition Sediment dropped when energy decreases
Aeolian processes
Process Description
Deflation Wind erosion and entrainment of sediment
Transportation Wind-blown movement of sediment
Deposition Occurs when wind strength decreases
Coastal landscapes are impacted by a number of physical factors. These impact the way coastal processes
within our coastal system work. This will therefore impact on the shaping of our coastlines spatially and
temporally
These factors are:
WINDS
• Wind is literally moving air particles from where there’s a lot to where there’s less. So, it’s air moving from areas of
higher pressure to areas of lower pressure along a pressure gradient.
• The bigger the difference between areas of high and low pressure, the more powerful the wind. A bigger difference
results in a steeper pressure gradient.
• Pressure gradients are created in several ways:
○ It can be caused by unequal heating of land and sea which will create local winds (on/offshore winds)
○ Air may be sucked up into the centre of an Atlantic, winter depression which may be very powerful and give
storm winds
○ A high-pressure weather systems in summer may migrate over the UK giving gentle winds
Onshore winds
• Land heats up more quickly during the day than water, so air rises creating a particle vacuum that ‘pulls’ in air off the
ocean to replace the air that is rising.
• This is called an onshore wind and can further strengthen any winds that are normally blowing towards the coastline.
coasts Page 4
04 September 2024 18:19
Glossary
Term Definition
Orthogonal Wave crest
Cusp Hollow semi-circular depression on a beach
Horn Protruding areas of material on a beach
Percolation Movement of water through rock (do not use infiltrate)
Continental shelf Large submerged area of seabed attached to the mainland
Halosere Salt marsh ecosystem
Halophytic plant Salt-tolerant plant
Alluvium Mud
Anthropogenic Caused by humans (e.g. anthropogenic climate change)
Estuarine Of or found in the (possibly tidal) mouths of large rivers
Carrying capacity How much sediment a river can carry
Abrasion (corrasion) Erosion caused when rocks carried by waves are thrown against a cliff
Attrition Rocks carried by waves collide and become smaller and more rounded
Hydraulic action Air trapped in cracks is compressed by waves, causing rock to break
Solution (corrosion) Chemical erosion where acidic seawater dissolves rock (e.g. limestone)
Longshore drift Movement of sediment along the coast by angled waves
Swash Movement of water up the beach at an angle
Backwash Movement of water back down the beach at 90° to the shoreline
Constructive waves Low-energy waves that deposit sediment and build beaches
Destructive waves High-energy waves that remove sediment and erode beaches
Fetch Distance of open water over which the wind blows to form waves
Wave refraction Bending of waves as they enter shallow water, focusing energy on headlands
Headland Resistant rock sticking out into the sea
Bay Area of softer rock eroded more quickly between headlands
Cave Hollow formed by erosion at the base of a cliff
Arch Cave eroded through a headland
Stack Isolated pillar of rock left after an arch collapses
Stump Eroded remains of a stack, visible at low tide
Beach profile Cross-section of a beach showing shape and slope
Berm Ridge of sediment at the top of a beach formed by constructive waves
Spit Narrow ridge of sand or shingle attached at one end, formed by longshore drift
Bar Spit that extends across a bay, cutting it off from the sea
Tombolo Spit connecting the mainland to an island
Salt marsh Low-energy coastal ecosystem that develops behind spits
Pioneer species First plants to colonise bare mud (e.g. glasswort)
Succession Gradual change in plant communities over time
coasts Page 1
,Succession Gradual change in plant communities over time
Hard engineering Man-made coastal defences that resist natural processes
Soft engineering Management that works with natural processes
Groynes Barriers that trap sediment moved by longshore drift
Sea wall Concrete barrier that reflects wave energy
Rock armour (rip-rap) Large boulders placed at the base of cliffs to absorb wave energy
Managed retreat Allowing low-value land to flood naturally to reduce risk elsewhere
coasts Page 2
,① Coastal Landscapes as a System
15 October 2024 11:10
A geographical system is a group of objects and the relationships between them. They store and transfer energy and material on time scales that can vary from a few days to
millennia
Coastal landscapes are recognised as open systems because a) energy and matter can be transferred from neighbouring systems as an input b) energy and matter can be transferred
to neighbouring systems as an output
Inputs
↙ ↓ ↘
Processes Stores Flows
↘ ↓ ↙
Outputs
The energy available to coastal landscapes may be kinetic, potential (GPE) or thermal
SEDIMENT CELLS
• Sediment movement occurs in distinct areas called cells
• Cells are a stretch of coastline within which the movement of sediment, sand and shingle is largely self-contained
• A sediment cell is a stretch of coastline and its associated nearshore area within which the movement of coarse sediment, san d and shingle is largely self-contained
• If part of a larger cell, they are called sub-cells
• Sediment cells are considered to be a closed system as the sediment stays largely within the cell - however in reality it is unlikely that sediment cells are completely closed
Throughputs/flows
Inputs → Components → Components → Outputs
Erosional processes Wind and water transport Wind and water transport
Energy from Erosional landforms Depositional landforms Dissipation of wave energy
• Wind
• Waves
• Tides
• Currents
Sediment Accumulation of sediment above the
tidal limit
Geology Sediment removed beyond local
sediment cells
Sea level
Equilibrium
Where there is a balance within a (coastal) system
Such as when inputs of energy and matter into that system and outputs of energy and matter out of that (coastal) system are t he same
Dynamic equilibrium
Natural systems are rarely in a constant state of static equilibrium as systems are always disturbed, with amplifications or reduction in inputs or energy and matter, or they may be
influenced by some external factor such as human activity
Therefore, they often self-regulate and produce their own response to such events through negative feedback mechanisms
Negative feedback
When a system self regulates to restore order and balance
coasts Page 3
, ② Factors Influencing Coastal
Landscapes
15 October 2024 15:12
Marine processes
Process Types / Examples
Erosion Hydraulic action, abrasion (corrasion), attrition, solution
Transportation Longshore drift
Deposition Occurs when wave energy decreases
Weathering processes
Type Processes
Biological Chelation, plant roots, marine organisms
Mechanical (physical) Freeze–thaw, pressure release, salt crystallisation
Chemical Carbonation, solution, oxidation, hydration, hydrolysis
Mass movement processes
Type Description
Falls Sudden movement of material from steep slopes or cliffs
Slides (linear and rotational) Movement of material along a slip plane
Fluvial processes
Process Description
Erosion Wearing away of river bed and banks
Transportation Movement of sediment by a river
Deposition Sediment dropped when energy decreases
Aeolian processes
Process Description
Deflation Wind erosion and entrainment of sediment
Transportation Wind-blown movement of sediment
Deposition Occurs when wind strength decreases
Coastal landscapes are impacted by a number of physical factors. These impact the way coastal processes
within our coastal system work. This will therefore impact on the shaping of our coastlines spatially and
temporally
These factors are:
WINDS
• Wind is literally moving air particles from where there’s a lot to where there’s less. So, it’s air moving from areas of
higher pressure to areas of lower pressure along a pressure gradient.
• The bigger the difference between areas of high and low pressure, the more powerful the wind. A bigger difference
results in a steeper pressure gradient.
• Pressure gradients are created in several ways:
○ It can be caused by unequal heating of land and sea which will create local winds (on/offshore winds)
○ Air may be sucked up into the centre of an Atlantic, winter depression which may be very powerful and give
storm winds
○ A high-pressure weather systems in summer may migrate over the UK giving gentle winds
Onshore winds
• Land heats up more quickly during the day than water, so air rises creating a particle vacuum that ‘pulls’ in air off the
ocean to replace the air that is rising.
• This is called an onshore wind and can further strengthen any winds that are normally blowing towards the coastline.
coasts Page 4
