Coastal Topic Flashcards
Name The Inputs Of A Coastal System
Land, people, atmosphere, marine, solar energy, waves, wind, tides
Name The Outputs Of A Coastal System
Erosion, Transportation, deposition, weathering, mass movement, salt marsh, wave cut platform, long shore drift, abrasion, freeze thaw
What Is The Top Of A Wave Called
The crest
What Is The Bottom Of A Wave Called
The Trough
What Is A Wave Length
The distance between each crest
What Is The Hight Of A Wave Called
The amplitude
What Is Wave Frequency
The amount of waves that pass a certain point in a time frame
Name The Key Aspects Of Destructive Waves
*Strong backwash
*Weak swash
*Appears on steep beaches because it washes the beach away
*Washes away sediment
*Deposits sediment off shore
Name The Key Aspects Of Constructive Waves
*Strong swash
*Weak backwash
*Build up beaches
*Deposits sediment onto the beach
How Is Sediment Formed
Sediment is formed from eroded cliffs and rocks
Why Can Building Sea-Walls Be Bad
Because by building sea walls we are stopping the coast from being eroded, which reduces the amount of sediment that constructive waves can deposit
Explain The Negative Feedback System Of Waves
Destructive waves wash away the beach until it is too steep for them to continue, they turn into constructive waves which build the beach backup. Once the beach is built up, destructive waves return to erode the sediment. And the cycle continues
What Force Created By The Moon Creates Tides
Centrifugal force
Why Is There A High Tide On The Side Of The Earth Closest To The Moon
Because the gravity of the moon pulls the water towards it
Why Is There A High Tide On The Side Of The Earth Opposite The Moon
Because the moons gravity pulls the earth into the center of the water meaning some “sticks out” on the other side
Why Are There Two High Tides And Low Tides In 24 Hours
Because a singular point on the earth passes through both high tides and low tides in a 24 hour period
Define Spring Tides
Spring tides are tides that occur every 14 days, they occur when the sun is in line with the moon. This causes extra gravitational pull on the oceans causing higher high tides, and lower low tides. They occur on full moons and new moons
Define Neap Tides
When the sun and the moon are at 90 degrees from each other, this makes the tide line a circle, meaning that there isn’t much difference between high tide and low tide. They occur every 14 days on a quarter moon
What Is Tidal Range
The difference between high and low tide
What Is The Cool Temperate Western Maritime Climate
The CTWMC is between 45-65 degrees of the equator and causes high energy waves where the north and south winds meet.
Why Do Winds Blow To The West
The Coriolis force means that the earth spins to the right. If you went straight south in the atmosphere you would end up west of where you wanted to be. Because of this effect, the winds are pushed westwards with the spin of the earth.
What Current Causes Wind
Convection current. As the hot air rises higher into the atmosphere, cold air rushes along the surface of the earth to fill the gap the rising air created. As the hot air moves along towards the cooler temperature and gets colder, it sinks.
What Is A High Pressure System
A high pressure system the when the cold air sinks towards the surface of the earth
What Is A Low Pressure System
When the hot air rises higher into the atmosphere
What Are High Energy Coasts
High energy coasts are area with high energy waves caused by the CTWMC
Where Are Storm Wave Environments Found
Between 45-65 degrees because of CTWMC
What Causes The East Coast Swell
The east coast swells are found on the east coast of each continent bellow the tropic of Cancer caused by NE and SE trade winds
Where Are Tropical Cyclone Coasts Found
Tropical cyclone coasts are found in the high pressure areas either side of the equator
What Are Trade Winds
The trade winds are winds that reliably blow east to west just north and south of the equator.
What Are Prevailing Winds
Prevailing winds are winds that blow from a single direction over a specific area of the Earth.
Air Pressure System Sheet
Define A Storm Surge
An abnormal rise of water generated by a storm, over and above the predicted astronomical tides
Why Does The UK Have Big Waves
The whole of the UK has big waves because there are wind blowing in from the North-East and the South-West
What Is The ‘Formula’ For A Storm Surge
Spring tide + low pressure storm + bulge in the sea = storm surge
Why Do Low Pressure Systems Cause Bulges In The Ocean
High pressure pushes the ocean to create a concave surface. Low pressure draws air up and in doing so the air pulls the water into a bulge as it moves across the ocean and rises
What Is The Coriolis Force
When all the water is diverted to the right because of the spin of the earth
Name And Explain The Human Causes Of Storm Surges
*Damming the rivers (flood defences) - decreases deposition in the estuary e.g. less salt marshes. This eliminates a natural defence
*Management of coasts - alter the amount of protective beach material that would be deposited acting as a barrier to rising sea levels. (sea walls)
*Building on coastal low lands makes people vulnerable to area that would flood naturally
*Global warming causes warmer weather which causes the sea to expand and sea levels to rise. Length of rainfall has been the most exceptional for 248 years
What Is A Sediment Cell
A sediment cell is a stretch of coastline usually bordered by two prominent headlands or anything that stops sediment movement. Where the movement of sediment tends to be contained.
Inputs Into A Sediment Cell
These are primarily derived from the river, coastal erosion and off shore sources, such as bars and banks
Transfers In Sediment Cells
The involve longshore drift together with onshore or offshore processes such as rip currents
Stores In A Sediment Cell
These include the beach, sand dunes, and offshore deposits (bars and bands)
Define Currents
The permanent or seasonal movement of surface water in the sea and oceans
What Is An Upwelling Current
The movement of cold water from deep in the ocean towards the surface. The more dense cold water replaces the warmer surface water and creates a nutrient rich cold ocean current. These form part of the global ocean circulation currents.
What Is Longshore Current
Also known as littoral drift, occur as most waves do not hit the coastline head on but approach at an angle to the shoreline. This generates a flow of water (current) running parallel to the shoreline. This not only moves water along the surf zone but also moves sediment parallel to the shoreline.
What Is A Rip Current
Rip currents occur when the receding flow becomes concentrated in one particular area at one particular time. There are a number of things that can cause this but the most common is a break in a sand bar.
Define Mass Movement
The movement of consolidated and unconsolidated material due to gravity
Define Consolidated Rock
Solid rock
Define Unconsolidated Rock
Soft rock (clay and soil)
Why Do We Have Boulder Clay Along The Coast
The boulder clay that we build on is so compact because as glaciers moved towards our coast, it pushes the mud and material from the sea bed against the coast
Name The Five Type Of Mass Movements
- Rotational slump
- Soil creep
- Land slide
- Rock fall
- Mud flow
Explain Soil Creep
Occurs where there is a very slow but continuous movement of individual particles down slope. There is an uncertainty about the exact cause of soil creep but it is agreed that the presence of soil moisture together with a range of weathering and other processes is significant.
Explain Rotational Slupming
Where softer material overlies resistant materials, cliffs subject to slumping. With excessive lubrication whole sections of cliff face may move downwards with a slide plane that is concave producing rotational movement. Slumps are common features of the British coast, particularly where glacial deposits form part coastal areas
Explain Landslides
Occur on cliffs made from softer rock or deposited material, which slips as a result of failure within it when lubricated, usually following heavy rainfall
Explain Rock Falls
These occur from cliff undercuts from the sea, or on the slopes affected by mechanical weathering action
Explain Mudflows
Heavy rain can cause large quantities of fine material to flow downhill. Here the soil becomes saturated and if excess water can not perculate deeper into the ground, surface layers become very fluent and flow downhill. The nature of the flow is dependent on the level of saturation, sediment type and angle of the slope
Name The Four Types Of Marine Erosion
- Hydraulic action
- Wave quarrying
- Abrasion / corrosion
- Attrition
Explain Hydraulic Action
Air trapped in cracks in the cliff due to force of water. This exerts enormous pressure on the rock surface
Explain Wave Quarrying
Breaking waves trap air as it hits the cliffs, as the water pulls back, there is an explosive effects of air under pressure being released
Explain Abrasion/Corrasion
Material in the sea wears away the rock face. Sand, shingles and boulders hurled against the cliff do enormous damage. This is apparent in inter-tidal rock platforms where sediment is drawn back and forth, grinding away at the platform
Explain Attrition
Rocks in the sea slowly worn down into smaller and rounder pieces
Name The Factors Affecting The Rate Of Erosion
- Wave steepness and breaking point
- Position of coast
- Fetch
- Human activity
- Sea depth
- Beach pressure
- Coastal Configuration
Explain How Wave Steepness And Breaking Point Affect The Rate Of Erosion
Steeper waves have more power than low waves. Waves breaking at cliff foot release more energy than those near shore
Explain How Position Of Coast Affects The Rate Of Erosion
Coasts not protected from prevailing winds are more exposed to wave action than sheltered coast areas
Explain How Human Action Affects The Rate Of Erosion
People may move protective materials from the beach, e.g. sand and shingles, leading to more erosion. Sea defenses increase erosion rates else where on the coast
Explain How Sea Depth Affects The Rate Of Erosion
A steady shelving sea bed at coast will create higher / steeper waves
Explain How Beach Gradient Will Affect The Rate Of Erosion
Beaches absorb wave energy which provides protection against erosion. Steep and narrow beaches quickly dissipates energy from flat waves. Flat beaches dissipates steep waves
How Do Headlands Attract Energy
Headlands attract wave energy though refraction
Explain How Fetch Affects The Rate Of Erosion
How far waves travel determines energy level
Name The Three Types Of Sub-Areal Processes
- Mechanical
- Biological
- Chemical
Explain Mechanical Weathering
Dependent on the nature of the climate. Freeze thaw action is common in latitudes where temperature fluctuate between above and below freezing, especially as there is a ready water supply. Water that enters the cracks in the rocks freezes as temperatures remain below 0 degrees. As it freezes water expands almost 10% meaning more space is occupied thus more pressure is exerted on the surrounding rock. As the process repeats and continues, cracks widen and eventually pieces of rock break of. Weathering and mass movement remove any overlaying material and the rock beneath experiences pressure release. This can cause weaknesses and more cracks as it is allowed to expand.
Explain Biological Weathering
Includes processes leading to the breakdown of rock by action of vegetation and coastal organisms. Quite active on coastlines, some marine organisms e.g. piddock (shellfish) have specially adapted shells that enable them to drill into rock. Particularly active in areas with chalk geology, seaweed attaches itself to rocks and the action of the sea can be enough to cause swaying seaweed to pry away loose rock from the sea floor. Algae secretase chemicals capable of promoting solution. Some animals can weaken cliffs as they burrow/dig into them e.g. rabbits
Name The Four Types Of Chemical Weathering
- Oxidation
- Hydration
- Hydrolysis
- Carbonation
Explain Oxidation
Causes rock to disintegrate when oxygen dissolved in the water reacts with some rock minerals, forming oxides / hydroxides. Evidence is a brownish/yellowish staining on the rock surface
Explain Hydration
Makes rocks more susceptible to further chemical weathering, involved physical addition of water to rock minerals. causes rock to expand, creating stress which causes rock to disintegrate. This process weakens the rock and creates cracks which allows the rock to be further weathered
Explain Hydrolysis
Mildly acidic water reacts / combines with minerals in rock to create clay and dissolvable salts which degrades rock beds, both weather than parent rock thus more susceptible to weathering
Explain Carbonation
Occurs when CO2 dissolved in rainwater makes carbon acidic water react with calcium carbonate in limestone to create a calcium bicarbonate which then dissolves in water. More effective in locations with cooler temperatures as more carbon
Explain Run Off
It may take the form of a stream emerging in a bay, taking with it large quantities of of load during times of flood, or maybe a stream cascading over a cliff excavating a V-shaped groove as it does so. It can also be water that flows over the surface to reach the coastline, the presents of which will assist many of the mass movement process
Name The Four Types Of Transport
- Traction
- Saltation
- Suspension
- Solution
Name The Four Types Of Transport
- Traction
- Saltation
- Suspension
- Solution
Explain Traction
Large stones and boulders are rolled along the sea bed and beach by moving sea water which happens in high energy environments
Explain Saltation
Small stones bounce along the sea bed and beach. It is associated with relatively high energy conditions. Small particles may be thrust up only to fall back down to the sea bed. As they land they dislodge other particles upwards causing bouncing movements
Explain Suspension
Very small particles of sand and slit are carried and picked up via turbulence in the water
Explains Solution
Dissolved materials are transported within the mass of moving water
Explain Wave Refraction
The friction from the shallow wave cut platform slows the waves on top of it, creating closer together waves, increasing the wave height. These destructive waves turn inwards towards the headland because of refraction (when part of something slows and the part remaining at the original speed is forced to spin). Because of the frequency and strength of the waves, the headland becomes a high energy area. The waves in the bay are low energy waves and are constructive.
How Are Headlands And Bays Formed
Headlands are formed when a section of consolidated rock is surrounded by unconsolidated rock. The unconsolidated rock is eroded leaving the consolidated rock “sticking out” and forming a headland. The area between two headlands that is eroded away is called a bay
Name The Three Types Of Beaches
- Sand beaches
- Shingle beaches
- Storm beaches
What Are The Key Points Of Storm Beach
- Built up by a strong swash during spring high tides
- Consists of large caliber material thrown up by the largest waves
- Remains unmoved because subsequent tides cannot reach them
- At the back of the beach
What Are The Key Points Of A Shingle Beach
- When the swash moves in the water moves between the pebbles and loses energy so the backwash is less strong
- Shingle beaches may make up the whole beach or just the upper part due to high spring tides where the waves have more energy and are higher steeper gradient (10-20 degrees)
What Are The Key Points Of A Sand Beach
- Gentle gradient (5 degrees)
- Sand particles are small - they fit together and squish very well
- Unlike the shingle beaches, the waves don’t lose much energy and so have a stronger backwash
What Are The Seasonal Changes To A Beach
In winter it is windier and so destructive waves are more common and the beach is washed away. In summer it is less windy and so constructive waves are more common and the beach is built back up
What Is Deposition
It occurs when accumulation of sand and shingles is faster then the removal. occurs when there is low energy and a large supply of materials
Explain Ridges And Runnels
- Occurs at specific points for wave activity such as the mean turning points for low and high tides where the cycle goes from neap to spring
- Run parallel to the shoreline
- Broken by channels that drain water off the beach
- Caused by strong backwash on sandy beaches
Explain Cusps and Ripples
Ripples are little ripples in the sand caused by small currents
cusps are semi circular depressions when waves break on the beach and the swash and back wash are strong. It happens at the junction between the sand and shingle. Sides of the cusp channel the swash into the middles deepening it.
Explain Tombolo’s
- Where a beach extends out to join an off shore island through longshore drift
Explain Bar’s
- When longshore drift connects two headlands
- Joins one end of the Bay to the end
- A lagoon is the still salt water behind the bar
Explain Barrier Islands
- Coastlines paralleled by off shore narrow strips of sand dunes, salt marshes and beaches are known as barrier Islands
- Barrier islands complexes stretches along the south east coast of North America from Long Island. New York to the gulf coast of Texas
- Many believe barrier islands originated as off shore bars built by waves breaking on a shallow shore
- The return backwash sweeps sand back to settle on the developing bar
Explain Spits
Long narrow accumulations of sand and / or shingles with one end joining the mainland and the other projecting outwards to the sea or extending partway across an estuary.
They often have a hooked end due to the second prevailing wind, fetch or wave refraction carrying some material into more sheltered water
What Is Needed For A Spit To Form
- Longshore drift
- Shallow and sheltered water
- Change in shape of coastline
Define Flocculation
When ocean and river water meet and electrically charge the clay starts to stick together and form mud
What Is The Definition Of Sand Dunes
Coastal sand dunes are accumulation of sand shaped into mounds by the wind
Explain Seral Stage 1 Of Sand Dunes
- Embryo dunes are very small dunes created by sand being blocked by small plants (pioneer plants) that are often submerged at high tide. Plants like sea rocket, sea couch and saltwort
- These plants have a high salt tolerance to survive in the sea environment
- When these embryo dunes grow a bit bigger, sea grass grows on top of them, making then now Foredunes
Explain Seral Stage 2 Of Sand Dunes
- Seral stage 2 has yellow dunes
- There is now no salt water reaching the dune
- There is also nutrient in the dune that can sustain plants
- It is covered in Marram grass
- All the pioneer species have died out
Explain Seral Stage 3 Of Sand Dunes
- Grey dunes have now formed
- It is completely protected from salt water due to yellow dunes in front of it
- The moss growing on it makes it grey
- It is no longer mobile and cannot be moved because of the plants and root
Explain Sand Dune Succession
The dune flattens out and is now just part of the ground. plants like heather and sedge grown over it and eventually pine trees until it becomes a forest
Outline The Key Points Of A Salt Marsh
- Located inland side of spit
- Low lying areas of the shore that are submerged at high tide and are composed of slit and clay
- Develop in estuaries where the flow of fresh water out the river is slow and the sea water flow into the river mouth with each high tide and out with each low tide
- At low tide the intertidal area of mud is left exposed. water is only left in permanent channels and the generally smooth surface shows evidence of tidal action where the flowing water has carved into, or shaped the surface
- Mud flats can be very extensive covering many tens of square kilometers
What Is The Definition Of Hard Engineering Strategies
Building or creating something which will interfere with costal processes
What Is The Definition Of Soft Engineering Strategies
Working with the natural processes of sea and sand in a more environmentally sustainably way
Explain The Concept Of “Rollback”
In which businesses or dwellings physically move further inland away from the treat of coastal erosion has been identified as a way to furthering sustainable coastal economic, environmental and social infrastructure development.
Name Nine Types Of Hard Engineering Strategies
-Concrete sea wall
-Revetment
-Gabions
-Rock armor / rip-rap
-Tetrapod’s
-Groynes
-Cliff drainage
-Barrages
-Offshore breakwater
Explain Sea Wall And The Advantages And Disadvantages
A concrete wall against the cliff face/ shoreline that deflects waves back into the sea.
Advantages: deflects waves, strong, effective, long lasting, often a promenade to walk along
Disadvantages: expensive, regular repairs, can undermine foundations, unnatural to look at
Explain Revetment And The Advantages And Disadvantages
Interlocking concrete slabs or wooden boards to deflect the waves. Placed at the foot of the cliff or the top of a beach to break up the energy or the waves
Advantages: provides hard face to cliff, easily installed, cheaper than sea wall, deflects wave power
Disadvantages: can be eroded from below easily, needs frequent repair, not very attractive
Explain Rock Amour And The Advantages And Disadvantages
Granite boulders placed at the base of the cliff / top of the beach to break waves and absorb the energy.
Advantages: popular in resent years, cheaper than sea wall
Disadvantages: not very attractive, not easy for people to get to beach, rats may live in the spaces
Explain Groynes And The Advantages And Disadvantages
Wooden or boulder ‘fences’ designed to trap and accumulate sand
Advantages: builds up the beach, makes the beach wider, provides calmer waters, encourages tourism
Disadvantages: needs repairs, strong waves can still reach cliffs, leads to faster erosion down the coast
Name Four Types Of Soft Engineering Strategies
-Beach nourishment
-Dune regeneration
-Marsh creation
-Landuse management
Explain Beach Nourishment And The Advantages And Disadvantages
Moving sand from areas it has accumulated to areas it has been eroded from, making the beach higher and wider
Advantages: adds to tourist amenity by making the beach bigger, attractive, works with natural processes, relatively cheap to maintain
Disadvantages: needs frequent renewal of more sand, doesn’t protect cliff from winter storm waves
Explain Dune Regeneration And The Advantages And Disadvantages
Marram grass can be planted to stabilize sand dunes and help them to become re-established. Areas can be fenced off to keep people off newly planted dunes
Advantages: maintains a natural coastal environment, provides important wildlife habitats, relatively cheap and sustainable
Disadvantages: time consuming, people do not always like being banned from certain areas
Explain Marsh Creation And The Advantages And Disadvantages
This is a form of managed retreat, by allowing low lying areas to become flooded by the sea, the land becomes a saltmarsh
Advantages: relatively cheap, provides a buffer to powerful waves, creates an important wildlife habitat
Disadvantages: agricultural land is lost, farmers/ landowners need to be compensated
Explain Landuse Management And The Advantages And Disadvantages
Even if some areas of the coast will eventually be flooded landuse management can minimize the impact. eg: caravan parks on cliff tops are appropriate because they can easily be moved and re-sited
Advantages: an appropriate behavioral approach to coastal management that is sustainable
Disadvantages: some people may not want to have land use restricted at the coast, difficult to implement retrospectively
What Is The Name Of The Case Study For Soft Engineering
Pevensey Bay
Describe The Location Of Pevensey Bay
It is located on the South coast of England in the between Eastborn and Hastings
How Much Does It Cost To Defend Pevensey Bay And Were Does This Money Come From
The initial budget for the 25 year contract awarded by the government was £30 million
What Sea Defenses Are In Place At Pevensey Bay
Shingle ridges, they are mounds made of shingles shaped in a stair. And groynes as well
What Is Pevensey Bay’s Strategy For The Beach
They are Holding the line by methods like beach nourishment, beach recycling and the recycling of old tires to raise the beach height
Are The Methods Being Used At Pevensey Bay Sustainable
No, because once the money and contract run out they won’t be able to run the ship and machines used to re-nourish the beach
