Coasts - A-Level Geography

Define a negative feedback loop

Changes are met with responses that restore the balance back to the original state - e.g the carbon cycle

Define a positive feedback loop

One change from the original state that triggers continuous problems, and cannot restore itself - e.g cliff erosion

What is the wave crest?

Highest point of the wave

What is the wave trough?

Lowest point of the wave

What is the wavelength or amplitude?

Distance between one crest/trough to the next

How is the wave height measured?

Distance from trough to crest

What is the wave fetch?

Distance of open water over which the wave has passed, being uninterrupted by obstacles

What is the maximum fetch?

Distance from one coastline to the next landmass. Often corresponds with the prevailing wind direction

What is the direction of prevailing winds in the UK?

South-West

How are tides caused?

gravitational pull of the sun and moon, happening twice a day

When does maximum high tide occur?

When the moon and sun are in line

What three points is wave energy controlled by?

Wind force and direction

Duration of wind

Fetch size

How are waves formed?

Wind blows over the surface of the water, creating drag and gaining grip, with the friction causing disturbance and forming waves as a result

Why don't objects travel forward in water?

Because waves have an orbital movement, and instead causes an up and down movement known as the swell

What happens when waves reach shallower water?

The movement is slowed by friction with the seabed, the wave increases in height due to the rising seabed level, becoming taller and thinner, eventually breaking and moving objects with it

The water comes up the beach as _______, and returns as __________

Swash, Backwash

Give features of a constructive wave

Deposit material, building gently sloping beaches

Created in calm weather

Strong swash, weak backwash

Low frequency (6-8 per min)

Long wavelength, low in height

Upper beach marked by ridges, berms, showing marks from previous high tide as the beach material builds up

Give features of a destructive wave

Created from distant storms, powerful

High wave energy with long fetch

High frequency (10-14 per min)

Strong backwash, weak swash

Short wavelength, steep height

Creates steeper beach profile as a result

Creates storm beaches, which are shingle ridges at the back of the beach or where large material is hurled and deposited

Give an example and explanation of high energy coastlines

Wave energy is strong throughout he majority of the year, e.g Western coast british isles. Prevailing and dominant wind direction is westerly, and face the longest fetch (across atlantic). Max wave height is greater on the west coast as opposed to the east

What is a high energy coastline?

Strong prevailing winds lead to high energy waves with greater erosion than deposition

Give an example and explanation of low energy coastlines

Islands add shelter, e.g the Isle of Wight, Estuaries and sheltered bays have lower wave heights, waves spread out and energy is dissipated. As a result, material is deposited. Enclosed seas also have these features e.g Baltic Sea, with some of the longest depositional landforms because of the sheltered water and low tidal range

What is a low energy coastline?

Low energy waves, deposition exceeds erosion rate

What is spring tide?

Gravitational pull of both sun and moon, when alligned gives a higher high tide and lower low tide, increasing the overall tidal range

Sun, moon and earth in straight line

Twice a lunar month

What is neap tide?

Sun and moon are at right angles to the earth, gravitational pull is less effective in comparison to alligned in spring tide. High tide is less and low tide is higher, giving a smaller tidal range. Occurs on alternate week, twice a month

What is tidal scour?

The movement/removal of large amounts of localised sediment by tidal currents

What are sediment cells?

Areas along the coastline where sediment is recycled within themselves, and are therefore considered closed systems - distinct areas of coastline separated by headlands

What are the boundaries of sediment cells?

Headlands and peninsulas, acting as natural barriers to stop further movement of the sediment

What can affect the some of the sediment in sediment cells under high energy conditions?

Even though the majority of the sediment will remain within the cell, some may move offshore into long term ocean floor stores. This could be due to changed in wind direction or movements of ocean currents

Within each sediment cell, there can be smaller ___________

Smaller sub cells. In England and Wales, there are 11 sediment cells, but each can be divided into smaller sub cells

What do sediment cells help with?

Sediment cells helps define coastal processes as a system, and assists in shoreline management plans (SMPs). Identifies the links between inputs, components, stores, transfers and outputs

What is an SMP?

Shoreline management plan

What is a sediment budget?

A balance between changes in the volume of sediment held within the system and the volume of sediment entering or leaving the system

Human interventions in a coastal system is likely to what?

In the form of coastal defences for example, is likely to have repercussions elsewhere in the system

What is a positive budget?

When there are more inputs than outputs to the system

What is a negative budget?

When the outputs are higher than the inputs to a system

What can cause input changes?

Volume of material being deposited into the coastal system and the impact that human intervention can have on that, e.g damming a river. Coastal defences can also impact on inputs with reduced cliff face erosion taking place. Sea level rise may add more sediment with increased coastal erosion

What can impact output changes?

Human intervention, e.g removing large amounts of sand from an area for industrial or coastal protection use. Sea level rise can increase likelihood of changing ocean currents and therefore material being removed from sediment cells

What are inputs to a coastal system?

Energy from waves, winds, tides and currents - intermittently increasing with storms

Sediment from erosion of the coastline and brought from rivers. Weathering and mass movement contribute material from cliff faces

Sea level changes as a consequence of climate change increases energy input along the coast. Geology of the coastline

What are outputs to a coastal system?

Coastal landforms - erosional and depositional

Accumulations of sediment above tidal range - dunes

Loss of energy from waves through refraction

Dissipation of wave energy

Sediment removed beyond local sediment cells

Give an example of a store in a coastal system

Water in the sea and shingle on beaches

What is a transfer in a coastal system?

Transfers from the action of wind and waves - e.g longshore drift

What is meant by dynamic equilibrium?

Balanced state of a system where the inputs and outputs are equal

If one element changes because of an outside influence in a coastal system, what occurs?

Upsets the internal equilibrium and affects other components of the system

What process allows a system to regain equilibrium?

By a process of feedback, the system adjusts to the change and regains equilibrium

Define equilibrium

The long term condition of balance or stability in a system, with inputs of energy and matter equal to outputs of energy and matter

Give and example of positive feedback in relation to sand dunes

Damage to vegetation on a sand dune by trampling causes erosion of sand, resulting in further loss of vegetation, more erosion

What is an isolated system?

There is no input or output of energy or matter. No interactions outside, for example the universe

What is a closed system?

There is input and output energy, however no matter. E.G the earth, where the sun is an input and elements are recycled

What is an open system?

Inputs and outputs of both energy and matter, E.G coasts

Where can feedback loops take place?

In any of the four spheres of earth - hydrosphere, biosphere, atmosphere and lithosphere

Where would lots of erosional landforms be found?

On a high energy coastline

Where would lots of depositional landforms be found?

On a low energy coastline

Collective term for mean, mode and median

Central tendency

What is another name for a sedmient cell?

Littoral cell

How many sediment cells are located around England and Wales?

11

Why is a wind rose diagram useful in geography?

Size of wind can be easily identified, as well as the direction. Can also be used to represent time and number of people in a given area for the human side of geography. Can also be plotted onto a map to show different data for different areas

The wind rose diagram is a type of _____ graph?

Radial graph

Define tidal bore

Sudden rise in the influx of water in a small estuary, e.g River Severn

What is a storm surge?

Important for generating waves, which can then travel long distances without losing power due to reduced pressure. Caused by low pressure and high wind speeds. Erosive

What is a subaerial process and what does it include?

Includes both weathering and mass movement. It is the breakdown of rock above tidal influence, e.g cliffs. "in situ"

What are the three types of weathering?

Chemical

Physical/Mechanical

Biological

What is carbonation?

Where rain falls through the air, and picks up CO2 from the air along the way

What is regolith?

Where the weathered product remains on top of the rock and acts as a protective layer, making it harder for weathering processes to penetrate the rock underneath

What is a eustatic change?

A global change in sea level

What is an isostatic change?

A local change in sea level

The typical sequence of sea level change can be separated into four stages. Describe each stage

Stage One: Climate gets colder, leading to snow and ice. Water stored on the land as ice causing sea level to fall, creating a eustatic change

Stage Two: Weight of the ice causes land to sink/submerge. This only affects more localised coastlines and is an isostatic change

Stage Three: Climate gets warmer causing ice on land to melt creating a eustatic sea level rise, with submergent features

Stage Four: Due to ice melt on land, land bounces back (isostatic readjustment). Localised. May form emergent features

What is currently happening over time to the land in the Scottish highlands due to previous eras?

Land is rising due to the rebound of the heavy ice from the Ice Age. This causes emergent features to form, such as raised beaches

Due to the rebound of the Scottish highlands, what is occuring on the south coast of the UK?

South coast begins to sink because the North is rebounding, being opposite ends. Submergent features form, such as rias and fjords

Many coastlines become _________ as a result of global warming

Submerged

A raised beach is an example of what kind of landform?

Emergent

What is a ria?

River valley drown by rising sea levels, causing floodplain to vanish. Has a dendritic drainage system meaning it had many contributing truibutaries. The cross section of a ria looks similar to a normal river

What is a fjord?

Glacial valley drowned by rising sea levels, with steep sides and is U-Shaped. Tends to be fairly straight and narrow

What is a dalmation coast?

Formed when the geology created valleys parallel to the coast so that when sea level rises, a series of elongated islands remain offshore - e.g Croatia

Rias, fjords and dalmation coasts are all examples of what?

Submergent landforms

What impact does sea level change have on storms?

Storms become more frequent and intense, impacting various ecosystems such as coral reefs, marshes and mangrove swamps, as well as settlements

Climate change causes sea levels to rise, making storms more frequent and intense. What happens because of this and what is affected?

Coastal erosion increases, meaning ecosystems, homes, businesses and communications are all at risk. Communications include roads and pipelines too

What impact does sea level change have on coastal flooding? Name an example

More frequent and severe coastal flooding in low lying areas. 1995 to 2004, kings point in NYC flooded 80 times. 2005 to 2024 it flooded 180 times (doubled)

What impact will sea level changes have on submergence?

Low lying islands will become submerged. A 0.5m sea level rise would submerge most of the maldives. A 0.3m rise would remove 8000 square km of our land

What impact does sea level change have on water sources and farmland?

Salt water inundation into lakes (ecosystems) and crop land (food insecurity)

What is meant by hard engineering?

Making a physical change to the coastal landscape using resistant materials, like concrete, boulders, wood and metal

What is meant by soft engineering?

Using natural systems for coastal defense, such as beaches, dunes and salt marshes, which can absorb and adjust to wave tide and energy

Give the main features of a sea wall

Hard engineering

Recurved to reflect waves back

Dissipate wave energy reflecting them back onto oncoming waves

Physical barrier to flooding

Continuous face - no gaps, or will be exploited by hydraulic action

Has drains, stops water accumulating inland

Give the main features of rock armour (riprap)

Hard engineering

Large boulders infront of a cliff or sea wall

Left angular to increase surface area

Dissipates wave energy

Not secured so that wave energy is dissipated by nudging them

Give the main features of groynes

Hard engineering

Can be wooden, stone or steel

Built at almost right angles to the waves

Control longshore drift and trap sediment

Could deprive beaches of sediment downshore

Give the main features of gabions

Hard engineering

Small rocks contained in a wire cage

Cages can be joined to create large structure

Dissipates wave energy

Can however rust from water so need replacing

Give the main features of revetments

Hard engineering

Concrete, wooden or stone

Place across beach or coastline to take force

Prevents further erosion to coast

Give the main features of cliff fixing

Hard engineering

Driving iron bards into cliff face

Stabalises and absorbs

Give the main features of offshore reefs in reference to hard engineering

Hard engineering

Force waves to break offshore, reducing impact at cliff base

Some ships deliberately sunk parallel to shore to slow waves, allowing reef material to colonise

Give the main features of barrages

Hard engineering

Large structures built to preventing flooding on major estuaries/sea inlets. Acts as a dam, prevents incursion of seawater into freshwater estuary

What are the main disadvantages to hard engineering?

Structures expensive to build and maintain

Defence in one area can impact badly elsewhere

Can be eyesore, disrupting natural habitat and landscape

Give the main features of beach nourishment

Soft engineering

Replacing material lost from longshore drift

Sand may be moved from one end of the beach to the other by local councils

Give the main features of dune regeneration

Soft engineering

Dunes are fragile and highly affected by human activity

Loss of vegetation could lead to blowouts, where large amounts of sand are carried inland onto agricultural land

Regeneration includes:

Stablising surface with wire mesh

Replanting vulnerable areas with marram grass

Restricting areas

Boardwalks for tourists

Selective grazing

Informing toursits

Give the main features of managed retreat

Soft Engineering

Flooding the land by abandoning the current line of sea defences

Land is reclaimed as Marsh

New marsh acts as a defence to rising sea levels, reducing hard engineering as well as costs

Give the main features of land-use management in soft engineering

Soft engineering

Authority can mitigate impact of flooding/erosion if inevitable

Educating the local community

Having caravan parks on areas at risk as can be easily moved

Population must agree to have their land use limited

Give the main features of the 'do nothing' idea in engineering techniques

Cheaper to let nature take its course

Allows money to be used elsewhere

Define mitigation

Action taken to reduce the severity of something or moderate their risk - e.g electric cars

Define adaptation

Actions taken to counteract new or chanibng environmewntal challened and reduce vulnerability of humans

Define resilience

Adapting what you do to increase your ability to cope with change in human issues or natural change

Define sustainable development

Development that meets then needs of the present without compromising the needs of future generations

Define chars

Sediment is deposited to form islands behind the dunes