physical landscapes in the UK

what type of rock forms upland areas

hard igneous and metamorphic rocks resistant to erosion

mechanical weathering of rocks

freeze thaw weathering - when temp of what is alternating between above and below 0 degrees

1. water enters a crack in the rock

2. when the water freezes it expands which puts pressure on the rock

3. when the water thaws it contracts, which releases the pressure on the rock

4. repeated freezing and thawing widens the crack and causes the rock to break up

chemical weathering of rocks

changes its chemical composition

carbonation happens in warm and wet conditions

1. rainwater has co2 dissolved in it which makes weak carbonic acid

2. carbonic acid reacts with rock that contains calcium carbonate, so the rocks r dissolved by the rainwater

what is mass movement

when material falls down a slope

the shifting of rocks and loose material down a slope and happens when the force of gravity acting on a slope is greater than the force supporting it

3 types of mass movement

1. slides - material shifts in a straight line along a slide plane

2. slumps - material rotates along a curved slip plane

3. rockfalls - material breaks up, often along bedding planes and falls down a slope

what is the fetch

the distance the wind blows over the sea

characteristics of destructive waves

they erode the coast

• high frequency and are high and steep

• BACKWASH more powerful than their SWASH so material is removed from the beach

characteristics of contructive waves

deposit material

• low frequency and low and long

• their SWASH is more powerful than the BACKWASH so material is deposited

3 processes of erosion which wear away the coast

1. hydraulic power - waves crash against rock and compress the air in cracks which puts pressure on rock and is repeated causing bits to break off

2. abrasion - eroded particles in the water scrape and rub against rock

3. attrition - eroded particles in the water, collide and break into smaller pieces and become more rounded

how does longshore drift work

1. waves follow the direction of the prevailing wind

2. waves hit the coast at an angle

3. the swash carries material up the beach in the same direction of the waves

4. the backwash then carries material down the beach at right angles, toward the sea

5. material zigzags along the coast

4 processes of transportation

traction - large particles like boulders are pushed along the sea bed by the force of the water

suspension - small particles are carried along in the water

saltation - pebbles are bounced along the sea bed by the force of the water

solution - soluble materials dissolve in the water and are carried

what is deposition and when does it happen

when water carrying sediment loses energy and slows down and drops its material

coasts build up when the amount of deposition is greater than the amount of erosion

what increases deposition rate

there is lots of erosion elsewhere on the coasr

constructive waves drop more material than they remove

examples of hard and soft rock

granite and sandstone

discordant vs concordant coastline

made up of alternating bands of hard and soft rock at right angles to coast

made up of alternating bands of hard and soft rock but parallel to each other (behind one another)

how are headlands eroded to form caves, arches and stacks (w/dorset coast examples)

1. the rock often has weaknesses like cracks

2. waves crash into the headlands and widen the cracks (hydraulic action and abrasion)

3. repeated erosion causes enlargement of cracks and a cave to form

4. continued erosion deepens the cave until it breaks through the headland to form an arch (Durdle door)

5. Erosion continues to wear away the rock supporting the arch, until it eventually collapses and forms an isolated arch, separate from the headland (Old Harry)

how are wave cut platforms formed

1. waves cause most erosion most at the foot of the cliff, forming a wave-cut notch

2. repeated erosion causes the rock above the notch to become unstable and it eventually collapses

3. collapsed material is washed away a new wave cut notch starts to form

4. this process is repeated and the cliff retreats, leaving a wave cut platform

how are beaches formed and where

formed by constructive waves between the high and low water marks

how are sand beaches formed

created by low energy waves and are flat and wide

sand particles are small so the weak backwash can move them back down the beach, creating a long gentle slope

how are shingle beaches formed

by high energy waves and are steep and narrow

sand particles are washed away but larger shingle is left behind and build up to create a steep slope

how are spits formed

at a sharp bend in the coastline, longshore drift transports material past the bend and deposits it out at sea

strong winds can curve the end of the spit forming a recurved end

how are bars formed

when longshore drift transports sand and shingle across a bay, connecting two headlands.

the bay between the headlands gets cut off from the sea and a lagoon can form behind the bar

offshore bars can also form if the coast has a gentle slope - friction w/ the sea bed causes waves to slow down and deposit sediment offshore

how are sand dunes formed

sand deposited by long shore drift is moved up the beach by wind

obstacles decrease wind speed so sand is deposited, forming small embryo dunes

they are stabilised by roots of vegetation which encourages more sand to collect there

this forms foredunes and eventually mature dunes, new embryo dunes form in front of the stabilised dunes

dune slacks (small pools) can form in hollows between dunes

swansea bay

discordant coastline - band of soft rock eroded faster than hard rock (clay/graphite)

sandy beach

hard engineering definition and examples

man-made structures built to control the flow of the sea and reduce flooding and erosion

1. sea walls - wall made of concrete that reflects waves back to sea

2. gabions - a wall of wire cages filled w rocks, at the foot of cliffs

3. rock armour - boulders piled up along the coast

4. groynes - wooden or stone fences that are built at right angles to the coast, trap material transported by longshore drift

positive and negatives of sea walls

prevents erosion of coast and acts as a barrier to stop flooding BUT creates a strong backwash that erodes under the wall + is expensive to build and maintain

positive and negatives of gabions

absorb wave energy and reduce erosion, fairy cheap BUT are quite ugly and the wires can erode away

positive and negatives of rock armour

aborbs wave energy ,reducing erosion and flooding and fairy cheap BUT boulders can be moved around by strong waves and need to be replaced

positive and negatives of groynes

create wider beaches which slows waves, give greater protection from flooding and erosion and fairly cheap

BUT they starve beaches further down the coast of sand, making them narrower and unable to protect the coast leading to greater erosion

soft engineering definition and examples

schemes set up using knowledge of the sea and its processes to reduce the effects of flooding and erosion

1. beach nourishing - sand and shingle from elsewhere added to upper parts of the beach

2. dune regeneration - creating or restoring dunes by nourishment or planting vegetation to stabilise the sand

positive and negatives of beach nourishment

creates wider beaches which slows the waves and gives greater protection from flooding and erosion BUT taking material from the sea bed can kill organisms and is very expensive and has to be repeated

positive and negatives of dune regeneration

creates a barrier between land and sea and absorbs wave energy, preventing flooding and erosion and stabilisation is cheap BUT the protection is limited to a small area and nourishment is v expensive

what is a managed retreat

allowing the sea to flood the land behind, the land will overtime become marshland which then protects the land behind from flooding and eroding

cheap and easy and can create new habitats for plants and animals

but can cause conflicts (may flood farmland and damage existing ecosystems)

case study for managed retreat and advantages and disadvantages

Medmerry managed retreat - west sussex

⚖ Advantages

• 🌱 Creates wildlife habitats (birds, salt marsh)

• 💰 Cheaper long-term than maintaining defences

• 🌊 Reduces flood risk to nearby towns

• 🌍 More sustainable (works with nature)

❌ Disadvantages

• 🚜 Loss of farmland

• 🏠 Some people unhappy about land being sacrificed

• 💸 High initial cost (~£28 million)

case study for coastal management and why it was needed

LYME REGIS - dorset southwest England

very powerful waves and much of the town is built along the edge of the cliffs, many properties have been damaged by landslides, slumps and wave breaching the sea walls

around 1km of lyme regis coastline is managed by hard engineering because:

has a pop of 3600 and around 500,000 tourists annually

main road goes along side the coast and it would have been lost within 50 years

the local economy relys on tourism (£42 million a year made by tourism alone in 2015) and tourism of the coast could threaten the historic town centre and tourism industry

overview of different phases of the protection scheme

1. built new rock armour on eastern side of sea front

2. sand shingle beaches were replenished and stabilised, rock armour was extended and drainage systems were improved to reduce water build up and prevent landslides(cost £26 million)

3. was meant to prevent landslides on the western side but was not carried out as v expensive

4. 390m of sea walls and rock armours and protects roads into town COST £19.5 million

positives and negatives of lyme regis

positives -

1. improved beaches have increased trade by arpund 20%

2. rock armour protects the habour and boats inside

3. ppl feel more inclined and secure buying property

negatives -

1. more tourists so more pollution, traffic and noise

2. defences stop new fossils being found in known fossilised areas

3. some think it was too expensive for a relatively short term solution as the defences could need rebuilding in around 60 years

what does a long profile show u about a river

how the gradient changes

what does a cross profile show

what a cross-section of the river looks like

upper, middle and lower course gradient, valley shape and channel shape

upper - steep, v-shaped valley, narrow and shallow

middle - medium, gently sloping valley sides, wider and deeper

lower - gentle, very wide, almost flat valley, very wide and deep

2 types of erosion that change cross profile of a river

vertical - deepens river valley and channel

lateral - widens the river valley and channels and dominant in middle and lower course of the river

4 processes of river erosion

hydraulic action - force of river water colliding w rocks breaks rock particles from the river channel

abrasion - eroded rocks picked up by the river scrape and rub against the channel, wearing it away

attrition - eroded rocks picked up by river crash into eachother and break into smaller fragments and get more rounded

solution - river water dissolves some types of rock

4 types of river transportation

traction - large particles like boulders and pushed along the river bed by force of the water

suspension - small particles are carried along by the water

saltation - pebble sized particles are bounced along the river bed

solution - soluble materials dissolve in the water and are carried along

deposition

when a river drops eroded material, river loses velocity and energy maybe bc:

• vol of water falls

• amount of eroded material increases

• water is shallower

• river reaches its mouth

where are waterfalls and gorges found

the upper course of a river

how are waterfalls and gorges formed

1. where a river flows over an area of hard rock followed by an area of softer rock

2. softer rock is eroded by hydraulic action and abrasion more than the hard rock, creating a step in the river

3. as water flows over the step it erodes more and more of the softer rock

4. a steep drop is eventually created, which is the waterfall (EG HIGH FORCE ON THE RIVER TEES)

5. the hard rock is eventually undercut by erosion and unsupported and collapses

6. the collapsed rocks are swirled around at the foot of the waterfall where they erode the softer rock by abrasion, creating a deep plunge pool

7. overtime, more undercutting causes more collapses and the waterfall retreats leaving behind a steep sided gorge

where are interlocking spurs found and how made

in the upper course of a river bc most erosion is vertically downwards, creating steep-sided, v shaped valleys

the rivers lack the power to erode laterally so they have to wind around the high hillsiddes that stik out into their path either side

the hillsides that interlock w eachother as the river winds around them are called interlocking spurs

how are meanders formed and where

middle and lower courses, in areas where the channel has both shallow and deep sections

1. current is faster on the outside of the bend bc the river is deeper (less friction to slow water)

2. so more erosion takes place on the outside of the bend, forming river cliffs

3. current is slower on the inside of the bend bc the river channel is shallower (more friction)

4. so eroded material is deposited on the inside of the bend, forming slip off slopes

how r oxbow lakes formed

1. erosion causes the outside bends to get closer until theres only a small bit of land left between the bends

2. the river breaks through this land, during flood mayb and the river flows over the shortest route

3. deposition eventually cuts off the meander forming an oxbow lake

what r flood plains

wide valley floor on either side of a river that occasionally floods

when a river floods the water slows down, loses energy and deposits the material its transporting which is built up on the flood plain

what are levees

natural embankments (raised banks) along the edges of a river channel

1. during a flood eroded material is deposited over the whole flood plain

2. the heaviest material is deposited closest to the river channel bc it is dropped first

3. this deposited material builds up, creating levees along the edges of the channel

what are estuaries

tidal areas where the river meets the sea

1. found at river mouths bc this land is closest to sea level and river channel is at its widest

2. water is tidal and when the water floods it carries and deposits sediment onto the valley floor

3. more mud builds there and creates large mudflats, at low tides the wide, muddy banks are exposed

what do contour lines on a map tell u

height and steepness of the land

upper course of river tees

• The upper course has hard impermeable rocks, vertical erosion has formed a V-shaped valley.

• High Force, the UK's largest waterfall by volume when in full flow is located in the upper course. An area of hard rock, called Whin Sill (or Whinstone), is located above a layer of soft rocks (sandstone and shale) and together they create this impressive waterfall.

middle course river tees

• As the River Tees starts to erode sideways (lateral erosion), it forms meanders. These can be identified in the middle course near Barnard Castle.

lower courses

• Near Yarm, the meanders in the lower course are much larger, and oxbow lakes have formed. In this area there are also levees which have formed when the river has flooded.

• The River Tees has a very large estuary with mudflats and sandbanks which supports wildlife in the area. Sites such as Seal Sands are protected areas.

what is the river discharge

the vol of water flowing in a river per second

measured in cumecs (cubic metres per second)

sections of a hydrographs

1. peak discharge

2. lag time (delay between peak rainfall and peak discharge)

3. rising limb (increase in river discharge as rainwater flows into the river)

4. falling limb (decrease in river discharge as the returns to its normal level)

physical factors affecting flood risk

1. heavy rainfall - water arrives too quickly to infiltrate so there is lots of surface runoff which increases discharge

2. geology - clay soils and some rocks are impermeable so run off is increased

3. prolonged rainfall - saturate soil and further rainfall cant infiltrate increasing runoff into river channels

4. relief (changes in land height) - if a river is in a steep-sided valley, water will reach the river channel quicker bc it can flow faster down the steep slopes - rapidly increasing discharge

human factors affecting flood risk

land use

1. building often made from impermeable materials and surrounded by roads made from impermeable surfaces, increasing surface runoff which man made drains then quickly transport into rivers, increasing discharge

2. trees intercept rainwater on their leaves which then evaporates. they also take up and store water from the ground so cutting them down, increases the vol of water that enter the river channel

what is hard engineering

man made structures built to control the flow of rivers and reduce flooding

4 types of hard engineering

dams and reservoirs

channel straightening

embankments

flood relief channels

what are dams and reservoirs and why are they good/bad

dams r barriers built across the rivers, usually in the upper course

reservoir (artificial lake) is formed behind the dam

BENEFITS -

reservoirs store water, control water flow and prevent floods downstream

and can be used to generate hydroelectric power

DISADVANTAGES -

very expensive to build and can flood existing settlements

material is deposited int eh reservoir not in the river so farmland downstream can become less fertile

what is channel straightening and why is it good/bad

meanders removed by building straighter, artificial channels

BENEFITS -

water leaves the ear more quickly so flood risk is lower

DISADVANTAGES -

flooding may happen downstream instead

faster moving water may cause more erosion downstream

what are embankments and why are they good/bad

raised walls are built along river banks

BENEFITS -

the river can hold more water so floods r less frequent

DISADVANTAGES -

quite expensive and risk of severe flooding if water rises above the embankment or if they break

what are flood relief channels and why are they good/bad

channels built to divert water around built up areas or divert excess water if levels get too high

BENEFITS -

gates on the channels mean that the release of water is controlled, reducing flood risk

DISADVANTAGES -

increased discharge where the relief channel rejoins the river, which could cause flooding there

what is soft engineering

schemes set up using knowledge of a river and its processes to reduce the effects of flooding

4 soft engineering methods

flood warnings and prep

flood plain zoning

planting trees

river restoration

what are flood warnings and prep and why r they good/bad

flood warnings are issues through various media

buildings r modified to minimise flood damage

residents can prepare sandbags and flood boards prior to floods

BENEFITS -

warnings give ppl time to move possessions to a safe place or put sandbags in place or evacuate

reducing flood impacts

DISADVANTAGES -

warnings dont prevent floods and some may not have access to warnings

modifying buildings is expensive

prep doesnt guarantee safety and could give ppl a false sense of security

what is flood plain zoning and why is it good/bad

restrictions prevent building on parts of flood plains that are likely to flood

BENEFITS -

risk is reduced bc fewer impermeable surfaces and impact of flooding is reduced as no buildings to damage

DISADVANTAGES -

expansion of a urban area is limited if there arnt any other suitable building sires

it cant help in areas w existing buildings

what is planting trees and why r they good/bad

increases the interception of rainwater and lag time

BENEFITS -

discharge and flood risk decreases

vegetation reduces soil erosion in the valley and provides habitats

DISADVANTAGES -

less land available for farming

what is river restoration and why is it good/bad

making the river more natural - eg removing man made levees so the flood plain can flood naturally

BENEFITS -

discharge reduced so theres less risk of flooding downstream

little maintenance is needed and there are better habitats for wildlife

DISADVANTAGES -

local flood risk can increase, especially is nothing is done to prevent major flooding

flood management scheme case study

banbury flood management scheme in 2012

• On the floodplain of the River Cherwell

• Population ≈ 45,000

COSTED £18.5 million

banbury major floods before scheme

• River Cherwell often burst its banks

• Major floods:

  • 1998 → 150 homes + businesses flooded, £12.5 million damage

  • 2007 → widespread flooding across the region

MAIN BANBURY FLOOD MANAGEMENT STRATEGIES

🏞 Flood storage area

• Large reservoir stores excess water (≈ 3 million m³)

🧱 Earth embankments

• Up to ~4.5 m high to hold water back

⚙ Flow control structures

• Control how fast water enters the river

🚧 Raised A361 road

• Prevents disruption during floods

💧 Pumping station

• Moves excess water away from the town

🌱 Environmental improvements

• Trees, ponds, hedgerows added (soft engineering)

social benefits of banbury

• Less flooding → reduced stress and anxiety

• Roads (A361) stay open → less disruption

• New green spaces improve quality of life

economic benefits of banbury

• Cost: £18.5 million

• Protects:

  • 441 homes

  • 73 businesses

• Benefits worth over £100 million

evnironmental benefits of banbury

• New habitats created (ponds, trees, hedgerows)

• Floodplain used naturally to store water

• Increased biodiversity

disadvantages of banbury

• Expensive (£18.5 million)

• Large amounts of earth needed → some habitat disruption

Some areas deliberately flooded (controlled flooding) - loss of farmland, damage to property in those areas and environmental disruption (short term)