Coatal Systems And Landscapes - PMT Essential Notes Flashcards
What is the coastal system defined as?
An open system that receives inputs from outside and transfers outputs away from the coast
Inputs and outputs can include terrestrial, atmospheric, or oceanic systems.
What are sediment cells?
Sections of coasts bordered by prominent headlands where sediment movement is contained
They act in dynamic equilibrium which can be disrupted by human interventions or natural variations.
What are the three main areas of coastal inputs?
- Marine: Waves, Tides, Salt Spray
- Atmosphere: Sun, Air Pressure, Wind Speed and Direction
- Humans: Pollution, Recreation, Settlement, Defences
What are the outputs of the coastal system?
- Ocean currents
- Rip tides
- Sediment transfer
- Evaporation
What are stores/sinks in the coastal system?
- Beaches
- Sand Dunes
- Spits
- Bars and Tombolos
- Headlands and Bays
- Nearshore Sediment
- Cliffs
- Wave-cut Notches
- Wave-cut Platforms
- Caves
- Arches
- Stacks
- Stumps
- Salt Marshes
- Tidal Flats
- Offshore Bands and Bars
What processes link inputs, outputs, and stores in the coastal system?
- Wind-blown sand
- Mass-movement processes
- Longshore drift
- Weathering
- Erosion
- Transportation
- Deposition
What is erosion in the coastal system?
- Hydraulic Action
- Corrosion
- Attrition
- Abrasion
What are the forms of transportation in the coastal system?
- Bedload
- In suspension
- Traction
- In solution
What are the types of deposition in the coastal system?
- Gravity Settling
- Flocculation
What drives the transfers and flows in the coastal system?
- Wind
- Gravitational
- Flowing Water
True or False: Sediment cells can contain smaller subcells.
True
What accounts for the majority of sediment in the coastal zone?
Rivers account for the majority of sediment in the coastal zone.
Sediment may be deposited in estuaries which are brackish and important wildlife habitats.
What is the significance of cliff erosion?
Cliff erosion is very important in areas with unconsolidated cliffs that are eroded easily. Most erosion occurs during the winter months due to more frequent storms.
How does wind contribute to sediment transport?
Wind is a coastal energy source that can cause sand to be blown along or up a beach.
Sediment transport by winds may occur where there are sand dunes, or in glacial and desert environments which provide sediment inputs.
What role do glaciers play in sediment deposition?
Glaciers can flow directly into the ocean, depositing sediment that was stored in the ice when they calve.
How is sediment transferred to the coastal zone?
Sediment is transferred to the coastal zone when waves, tides, and currents erode offshore sediment sinks such as offshore bars.
The sediment is transported onto the beach, helping to build up the beach.
What is longshore drift?
Longshore drift is the movement of sediment along the beach due to prevailing winds that alter the direction of the waves.
This allows sediment to be transported from one section of coastline (as an output) to another stretch of coastline (as an input).
What is a sediment budget?
Sediment budgets use data of inputs, outputs, stores, and transfers to assess the gains and losses of sediment within a sediment cell.
What is the principle of dynamic equilibrium in sediment budgets?
In principle, a system will operate in a state of dynamic equilibrium where input and outputs of sediment are equal.
However, human actions and natural variation in the system can disrupt the state of equilibrium.
What is the littoral zone?
The littoral zone is the area of land between the cliffs or dunes on the coast and the offshore area that is beyond the influence of the waves.
What factors cause changes in the littoral zone?
The littoral zone is constantly changing because of short-term factors like tides and storm surges, and long-term factors like changes in sea level and human intervention.
What is the primary source of energy for all natural systems?
The sun is the primary source of energy for all natural systems.
What is the main energy source at the coast?
The main energy source at the coast is from waves which are formed offshore.
How do waves form?
Waves form when wind moves across the surface of the water, causing frictional drag which creates small ripples and waves.
What happens to water particles as waves approach the coastline?
As the seabed becomes shallower towards the coastline, the orbit of the water particles becomes more elliptical, leading to horizontal movement of the waves.
What changes occur to wave height, wavelength, and wave velocity as waves approach the shore?
The wave height increases, but the wavelength and wave velocity both decrease.
What causes a wave to break?
Water backs up from behind the wave until the wave breaks (collapses) and surges up the beach.
What factor affects wave energy related to wind strength?
The larger the pressure gradient between two areas, the stronger the winds, resulting in stronger waves.
How does the duration of wind affect wave energy?
If the wind is active for longer periods of time, the energy of the waves will build up and increase.
What is the fetch in relation to wave energy?
The fetch is the distance over which the wind blows; the larger it is, the more powerful the waves will be.
What are constructive waves?
Constructive waves act to build up and create a beach and increase its size.
What are destructive waves?
Destructive waves act to remove the beach and decrease its size.
How are constructive waves formed?
Constructive waves are formed by weather systems that operate in the open ocean.
How are destructive waves formed?
Destructive waves are formed by localized storm events with stronger winds operating closer to the coast.
What is the wavelength of constructive waves?
Constructive waves have a long wavelength.
What is the wavelength of destructive waves?
Destructive waves have a short wavelength.
What is the frequency of constructive waves?
Constructive waves have a frequency of 6-9 per minute.
What is the frequency of destructive waves?
Destructive waves have a frequency of 11-16 per minute.
What are the wave characteristics of constructive waves?
Constructive waves are low waves, which surge up the beach.
What are the wave characteristics of destructive waves?
Destructive waves are high waves, which plunge onto the beach.
What are the swash characteristics of constructive waves?
Constructive waves have strong swash and weak backwash.
What are the swash characteristics of destructive waves?
Destructive waves have weak swash and strong backwash.
Where do constructive waves occur?
Constructive waves occur on gently sloped beaches.
Where do destructive waves occur?
Destructive waves occur on steeply sloped beaches.
What type of waves dominate in summer and winter in a coastal environment?
Constructive waves dominate in summer, while destructive waves dominate in winter.
Can constructive waves become destructive waves?
Yes, constructive waves may become destructive waves if a storm begins.
How might climate change affect storms in the UK?
Climate change may increase the storm frequency within the UK.
What impact can coastal management have on wave types?
Coastal management may affect the type of waves that occur.
What is the relationship between constructive waves and beach profile?
The presence of constructive waves causes deposition on the beach, leading to a steeper beach profile.
How do steeper beaches influence wave types?
Steeper beaches favour the formation of destructive waves, which are then more likely to occur.
What happens to the beach profile during summer and winter?
The beach profile is more gentle in summer and steeper during winter when destructive waves are more common.
What is tidal range?
The difference in height between the tides is known as the tidal range.
What creates a spring tide?
The highest high tide and the lowest low tide occur when the sun and the moon are in alignment.
What creates a neap tide?
The lowest high tide and the highest low tide occur when the sun and the moon are perpendicular to each other.
What are rip currents?
Rip currents are powerful underwater currents occurring close to the shoreline when plunging waves cause a buildup of water.
What is the effect of rip currents in coastal environments?
Rip currents are an energy source and can lead to outputs of sediment from the beach area.
What characterizes high-energy coastlines?
High-energy coastlines are associated with powerful waves, large fetch, rocky headlands, and frequent destructive waves.
What is the erosion-deposition relationship in high-energy coastlines?
High-energy coastlines are often eroding as the rate of erosion exceeds the rate of deposition.
What characterizes low-energy coastlines?
Low-energy coastlines have less powerful waves, occur in sheltered areas, and are often sandy.
What is the erosion-deposition relationship in low-energy coastlines?
In low-energy coastlines, the rates of deposition exceed the rates of erosion.
What is wave refraction?
Wave refraction is the process by which waves turn and lose energy around a headland on uneven coastlines.
What happens to wave energy during wave refraction?
The wave energy is focussed on the headlands, creating erosive features in these areas.
What occurs in bays during wave refraction?
The energy is dissipated in bays, leading to the formation of features associated with lower energy environments such as beaches.
How does erosion relate to rock strength?
Erosion leads to the formation of headlands where resistant rock exists and bays where unconsolidated rocks and clays are dominant.
What is the effect of wave refraction on headlands and bays?
Wave refraction dissipates wave energy, increasing erosion on headlands and reducing it in bays.
What is the outcome of headlands being worn away?
Eventually, the headlands are worn away, which then again increases erosion within the bays.
What is corrasion?
Corrasion is when sand and pebbles are picked up by the sea from an offshore sediment sink and hurled against the cliffs at high tide.
What is cavitation?
Cavitation is an erosive process where air bubbles implode under high pressure, creating tiny jets of water that erode the rock.
What is abrasion?
Abrasion is the process where sediment is moved along the shoreline, causing it to be worn down over time.
What is corrosion (solution)?
Corrosion occurs when mildly acidic seawater erodes alkaline rock such as limestone.
What is hydraulic action?
Hydraulic action occurs when a wave crashes onto a rock or cliff face, forcing air into cracks and causing them to force apart.
What is wave quarrying?
Wave quarrying is when breaking waves hit the cliff face to directly pull away rocks or remove smaller weathered fragments.
What are the factors affecting coastal erosion?
Several factors affect coastal erosion, which can be marine or land based.
These factors include Waves, Beach Size and Presence, Activity of Subaerial Processes, Rock Faults, and Rock Lithology.
What is one factor that affects coastal erosion?
Waves
Waves can contribute to the erosion of coastal areas.
How does beach size affect coastal erosion?
Beach Size and Presence
The size and presence of a beach can influence the rate of coastal erosion.
What role do subaerial processes play in erosion?
Activity of Subaerial Processes
Subaerial processes refer to weathering and erosion that occur on land.
What are rock faults?
Rock Faults
Faults in rock can create weaknesses that are susceptible to erosion.
What is rock lithology?
Rock Lithology
The physical and chemical characteristics of rocks can affect their erosion rates.