Paper 2 Section A - The Uk's evolving physical landscape

Name the three different types of rock:

• State how they are formed

• Their characteristics

• Where they are found in the UK

• Examples for each

• Igneous rocks

  • When lava cools and solidifies on the surface

  • The molten rock crystallises as it cools producing sparkly quartz within the rock; very hard and resistant; interlocking crystalline structure makes it impermeable

  • Predominantly found in the upland areas of Scotland, North Wales and Northern Ireland

  • Examples: Granite, basalt

• Sedimentary rocks

  • When weathering breaks existing rocks into particles (sediment) which are transported and deposited in layers; over time compress under pressure to form rock.

  • Made of distinct layers (as sediment is deposited in stages), usually softer and less resistant, sometimes contain fossils, often permeable due to gaps between sediment and many joints

  • Lowland areas of South England and South Wales

  • Examples: Chalk, carboniferous limestone, sandstone, clay

• Metamorphic rocks

  • Formed when existing rocks undergo intense heat and pressure

  • Very hard and resistant and usually impermeable (as the minerals have been compressed very tightly together), banded (as different minerals align into different bands/layers)

  • Upland areas of North Scotland, Northern Ireland, North Wales

  • Examples: Schist, slate, marble

Describe the role of geology, past tectonic and glacial processes in the development of upland and lowland landscapes

Geology:

• Igneous and metamorphic rocks are harder and more resistant to erosion, so tend to form upland landscapes

• Sedimentary rocks are usually softer and less resistant to erosion, so tend to form lowland land scapes

Past tectonic processes:

• Active volcanoes: millions of years ago, the UK used to be closer to a plate boundary; active volcanoes on the plate boundary forced magma through the Earth’s crust, which cooled to form igneous rocks (forming upland landscapes)

• Plate collisions: caused rocks to be folded and uplifted, forming upland mountain ranges.

• Plate collisions: the intense heat and pressure caused by plate collisions formed metamorphic rocks (forming upland landscapes)

• Plate movements: millions of years ago, past plate movements meant that Britain was in the tropics, and higher sea levels meant that it was partly under water.

  • Carboniferous limestone formed in the warm shallow seas when marine creatures died, forming uplands in South West England and Wales

Past glacial processes:

• During glacial periods, large glaciers moved, eroding the landscape and carving out u-shaped valleys

• When glaciers melted, they deposited lots of material. Large parts of Eastern England are still covered in till that was deposited

  • HANGING VALLEYS

  • OUTWASH PLAINS

  • MISFIT STREAMS

Describe the physical processes that have shaped the UK’s physical landscape

• Erosion; wearing and transportation of rock away

• Weathering: breakdown of rock into smaller pieces (mechanical, chemical, biological)

• Post-glacial river processes: after glaciers melted, rivers had greater discharge and therefore greater power to erode the landscape

• Slope processes (including mass movements)

Physical processes are affected by the climate (decreased/ increased)

Describe the different types of weathering

• Mechanical: breakdown of rocks through physical force without changing their chemical composition

  • Eg. salt weathering (as salt expands when water evaporates, widening cracks)

• Chemical: breakdown of rocks by changing its chemical composition

  • Eg. carbonation weathering as carbon dioxide dissolved in rain and oceans forms weak carbonic acids

• Biological: breakdown of rocks by living things

  • Eg. plant roots growing into rocks and pushing them apart

Describe the different types of mass movement

Mass movement is the shifting of rocks and loose materials down a slope; it occurs when the force of gravity acting on the slope is greater than the force supporting it

• Slides: material shifts in a straight line

• Slumps: material shifts with a rotation

• Rockfalls: material breaks up and falls down a slope

Describe the different types of erosion

• Hydraulic action: waves crash against rocks and compress the air in the cracks, putting pressure on the rocks. This repeated compression widens the cracks and makes bits of rocks break off

• Abrasion: sediment in the water scrapes and rubs against the rock removing small pieces

• Attrition: sediment in the water smash into each other and break into smaller fragments

• Solution: acidic water dissolves the rock, causing it to wear away

Describe how humans have caused distinctive landscapes to form

• Agriculture

  • People have cleared the land of forest to make space for cattle/ sheep farming

  • Hedgerows and walls have been built to mark out fields

  • Drainage ditches have been dug to make land dry enough for farming

• Forestry:

  • Trees have been planted in straight lines for timber

  • When trees are felled, the landscape is left bare

  • Some trees are being replanted to attempt to return the landscape to a more natural state

• Settlement:

  • Land was concreted over for roads and buildings

  • Some rivers were diverted or straightened

  • Some rivers had embankments built to prevent flooding

Explain the two different types of coastline and name the different landforms formed on each

• Concordant: rock strata is parallel to the coastline

  • High cliffs, coves

• Disconcordant: rock strata is perpendicular to the coastline

  • Headlands and bays

What are joints and faults?

Joints - small, vertical cracks in rocks

Faults - larger cracks

Explain why some coastlines erode more quickly than others

• Geology

  • Coastlines with soft, less resistant rock will erode more quickly

• Human activities/ value of land

  • (How human activities have effects on the coastline (eg. development, agriculture, industry, coastal management)

• Waves

  • The type of wave (constructive/ destructive) and the wave’s fetch and energy will affect the rate of coastal erosion

Explain how coves are formed

Coves are an erosional landform:

They form on concordant coastlines

• Erosion (name of erosion) weakens the rock, forming joints and cracks

• Over time the hard, resistant rock erodes to expose the soft, less resistant rock behind

• The less resistant rock erodes much faster than the more resistant rock, so the cove widens more in the soft rock band

• Erosion continues to widen the cove, but cannot extend further inland due to the band of rock behind the soft rock, which forms steep cliffs

Explain how wave-cut platforms are formed

Wave cut platforms are an erosional landform:

• Waves cause most erosion at the foot of a cliff

• This forms a wave-cut notch, which is enlarged as erosion continues

• The rock above the notch becomes unstable and eventually collapses

• The collapsed material is washed away and a new wave-cut notched starts to form

• The repeated collapsing results in the cliff retreating

• A wave-cut platform is the platform left behind as the cliff retreats

Explain how bays and headlands are formed

Headlands and bays are erosional landforms:

They form along disconcordant coastlines

• Soft rocks or rocks with lots of joints are less resistant to erosion compared to hard rocks with a solid structure

• The less resistant rock is eroded away quickly forming a bay

• The resistant rock is eroded more slowly and is left jutting out, forming a headland

Explain how caves through stumps are formed

Caves through stumps are erosional landforms:

They form on disconcordant coastlines on headlands

Cave, arch, stack, stump

• Waves crash into the base of the headlands enlarging cracks through hydraulic action and abrasion

• Repeated erosion and enlargement of cracks cause a cave to form

• Continued erosion deepens the cave until it breaks through the headland forming an arch

• Erosion continues to wear away the rock supporting the arch until it eventually collapses

• This forms a stack

• As erosion continues to attack the base of the stack, eventually it will collapse into a stump

Describe the impact of the UK’s climate on coastal erosion and retreat

Climate: the long term patterns of weather conditions in a specific area

Different seasons bring different weathers:

• In Summer, warm temperatures increase the rate of salt weathering

• In Winter, low temperatures cause freeze-thaw weathering

• Strong winds from storms create high energy, destructive waves which increase erosion

• Intense rainfall can cause cliffs to become saturated, causing mass movement

• Prevailing wind: mostly south westerlies which bring storms from the Atlantic Ocean; the UK’s south coast is exposed to these winds

Describe the different types of waves

• Constructive waves are depositional (they deposit more material than they erode), so build up beach material

  • Strong swash

  • Weak backwash

  • Low wave height

  • High wavelength

  • Low wave frequency

• Destructive waves are erosional (they arode more material than they deposit), so they remove beach material from the coast

  • Weak swash

  • Strong backwash

  • High wave height

  • Low wavelength

  • High wave frequency

What is a wave’s fetch?

The distance of the sea over which the wave has travelled

Describe the process of longshore drift

Longshore drift is the process by which material is transported along coasts

• Waves follow the direction of the prevailing wind

• They usually hit the coastline at an oblique angle (in the direction of the prevailing wind)

• The swash carries material up the beach in the same direction as the waves

• The backwash carries material back down the beach at right angles due to gravity

• Over time this causes material to zig zag along the coastline

Describe how beaches are formed

A beach is a depositional landform; beaches are large deposits of shingle and sand

• Deposition occurs when water carrying sediment slows down/ loses energy so that it isn’t moving fast enough to continue to carry the sediment, thus dropping it

• Constructive waves have a strong swash, so carry large amounts of material onto the coast

• However, they have a weak backwash so cannot carry the material back, thus depositing material such as sand and shingle along the coast to form beaches

Explain how a spit is formed

Spits are depositional landforms; they are long narrow strips of beach material

Sediment moved along a coastline by longshore drift (1) in direction of prevailing wind (1). The coastline changes direction (1) but the deposition of sediment continues (1)

• Spits form at sharp bends in the coastline

• Longshore drift transports sand and shingle past the bend and deposits it into the sea as it loses energy (usually due to going into a sheltered area behind the bend in the coastline)

• If the prevailing wind changes direction, strong winds and waves can curve the end of the spit, forming a recurved end

• The sheltered area behind the spit is protected from waves, therefore lots of material can accumulate behind this area, which means that plants can grow there

• Over time the sheltered area can become a mud flat or salt marsh

Explain how a bar is formed

Bars are depositional landforms; bars are spits that have grown across the mouth of a bay

• A bar is formed when a spit joints two headlands together

• The bar cuts off the bay between the headlands from the sea

• This means that a lagoon can form behind the bar

How to identify coastal landforms on maps (Caves-stumps, cliffs, wave cut platforms, spits)

• Caves, arches, stacks, stumps

• Cliffs

• Wave cut platforms

(Shown as bumpy edges along the coast)

• Spits

Explain how human activities have effects on the coastline

Development, agriculture, industry, coastal management

• Development:

  • Coastal areas are popular to live in, so often have lots of development infrastructure (eg. hotels, shops, homes, roads, power lines etc.)

  • Positive effects:

    • May mean more coastal protection as land has a greater value

  • Negative effects:

    • Building on cliffs adds weight to them, making them unstable and causing mass movement

    • Impermeable surfaces may alter natural drainage system (water goes to cliffs, saturated, mass movement)

    • Infrastructure may alter natural sediment movement (interrupt longshore drift) along the coast (starving further parts)

• Agriculture:

  • Clearing vegetation (eg. for grazing land)

    • Vegetation helps to bind soil together to stabilise cliffs with their roots. Removing this can make cliffs unstable and cause mass movement

    • Can expose underlying rock beneath the vegetation, making it vulnerable to weathering by wind and rain

  • Land (eg. marshland) is sometimes reclaimed and drained for agricultural use.

    • Reduces natural flood barrier that marshland provides

• Industry:

  • Coastal quarries (mine/ excavation sites) expose large areas of rock, making them more vulnerable to weathering and erosion

  • Gravel has been extracted from beaches for use in construction industries; this leads to increased erosion as there is less material to protect the cliffs

  • Industrial growth at ports has led to increased pressure to build on marshland - building on them removes the land's natural flood barrier, leaving it more vulnerable to erosion

• Coastal management:

  • Some management strategies (eg. groynes) can alter sediment movement, restricting it from reaching further down the coast. This can make the beach narrower, increasing erosion

  • Coastal defences can reduce erosion, which prevents the landscape from changing (eg. retreating)

Describe the significance of the coastal case study location

Named location: Christchurch bay

• Located on England’s WEST coast,

  • Vulnerable to powerful, long-fetch, destructive waves from the Atlantic

• Lots of residential areas and developments around the bay (HEAVY MANUFACTURING)

• Weak, less resistant geology (weak clays and sandstones)

The coastal landscape surrounding Christchurch bay has experienced landslides and cliff collapses due to extensive erosion and instability on the coastline.

Describe the physical processes along a named coastal landscape

Named coastal landscape: Christchurch bay

• Experiences South westerlies which bring full-force destructive waves from the Atlantic; these waves have a long fetch so are very powerful

  • These waves quickly erode the cliff bases (through hydraulic action and abrasion), making them unstable and vulnerable to collapse

• The cliffs are made of sandstones and clays; these rock types are easily eroded and weathered as they are very soft

• Its sandstone geology is highly permeable, meaning that water infiltrates the cliffs easily and saturates the cliffs during wet periods. This adds weight, increases instability and causes mass movement and cliff collapse

Describe the human processes along a named coastal landscape

Named coastal landscape: Christchurch bay

• Decades of erosion has caused the coastline to retreat by tens of metres, meaning that now many buildings are very close to the cliffs.

  • This extra weight on the cliff edge can cause cliffs to become too unstable and collapse (several houses and a cafe have already been lost)

• Poor planning has led to terminal groyne syndrome; starved the beach of sediment further east, causing rapid erosion

• Residential and industrial developments have led to impermeable surfaces further inland and altered the natural drainage system of the coastal area; more water is drained directly into cliffs, causing them to become saturated, leading to mass movement

Explain why there are increasing risks for coastal flooding

Climate change is causing an increased frequency of storms and rising sea levels

• Storm frequency

  • Storms bring high winds that give the sea more erosional power, removing natural defenses

  • The sea will have more energy to transport material over longer distances; this could lead to some areas being starved of material, leaving those areas vulnerable to erosion and flooding

  • Storm surges could become more frequent, leading to more frequent flooding

• Rising sea levels: as seas warm up, it leads to thermal expansion, so the volume of water in the ocean becomes greater.

  • This can cause higher tides, meaning that coastal areas flood more frequently

  • Higher tides can remove larger amounts of material from beaches, leading to increased erosion of cliffs as there’s less material to protect them from the sea

Give the threats of increased risk of coastal flooding to people

• Low-lying areas could become flood, causing them to become impossible to inhabit, forcing people to migrate elsewhere, causing overpopulation and strain on houses elsewhere

• Coastal industries may be shut down because of damage to equipment and buildings (eg. fishing boats destroyed)

• Risk of damage to infrastructure (roads and rails)

• Flooding and erosion can prevent tourists from visiting; fewer tourists mean that the businesses that rely on tourism may be forced to close, leading to a loss of livelihoods

Give threats of increased risk of flooding to the enviroment

• Flooding can cause damage to ecosystems as seawater have a high salt content; increased salt levels can damage or kill organisms

• The force of floodwater can uproot trees or plants

• Can threaten conservation areas (eg. if bars are eroded, protected lagoons will be destroyed)

Define hard and soft engineering

• Hard engineering: the use of artificial, man-made structures built to control natural processes (eg. to control the flow of the sea and reduce flooding and erosion)

• Soft engineering: involves the use of the natural environment, using knowledge of the environment to set up schemes to control natural processes (eg. to reduce the effects of flooding and erosion)

Name the hard engineering coastal defences

• Sea wall

• Groynes

• Rock armour

• Gabions

• Slope stabilisation (with concrete nails)

Give the benefits and costs for hard engineering coastal defences

Sea wall, groynes, rock armour, gabions, slope stabilisation

• Sea wall: A wall made out of a hard material like concrete that reflects waves back to sea

  • Benefits:

    • Prevents erosion of the coast

    • Acts as a barrier to prevent flooding

    • Can provide a walkway on top, providing tourism benefits

  • Costs:

    • Visually unappealing

    • Expensive to construct and maintain

    • Creates a strong backwash, eroding under the wall

• Groynes: Wooden or stone fences built at right angles to the coast that trap material transported by longshore drift

  • Benefits:

    • Allows the beach to build up, creating wider beaches which slow the waves, giving greater protection against flooding and erosion

    • Cheap defence

  • Costs:

    • Deprives areas further down of sediment, making them narrower and increasing erosion

    • Visually unappealing

• Rock armour: A barrier of large rocks placed before a cliff or sea wall to absorb wave energy and reduce backwash

  • Benefits:

    • Cheaper than sea walls

    • Quick and easy to construct

    • Does not impede longshore drift

  • Costs:

    • May affect access to the beach

    • Looks unattractive

    • Rock has to be quarried, which causes environmental damage

• Gabions: Wire mesh cages filled with pebbles or rocks, absorbing wave energy

  • Benefits:

    • Does not impede access to the beach

    • Cheap

    • Easy to construct

    • Do not impede longshore drift

    • Blend in better than most hard engineering (eg. when covered by sand, vegetation)

  • Costs:

    • Access to the beach is difficult

    • When damaged can be dangerous

    • Can be unsightly

• Slope stabilisation: slopes are reinforced by inserting concrete nails into the ground and covering the slope with metal netting

  • Benefits:

    • Relatively cheap

    • Minimal impact on the environment, enabling wildlife to live there

    • Prevents mass movement by increasing the strength of the slope

  • Costs:

    • Very time consuming to build

    • Can be damaged in a storm

Name the soft engineering coastal defences:

• Beach replenishment

• Slope stabilisation (with marram grass)

• Strategic realignment

Give the benefits and costs for soft engineering coastal defences

Beach replenishment, slope stabilisation, strategic realignment

• Beach replenishment: sand and shingle from elsewhere are added to the beach

  • Benefits:

    • Maintains the beach, which acts as a major tourist attraction

    • Blends in with the rest of the beach, so isn’t unattractive

    • Gives greater protection against flooding and erosion

  • Costs:

    • Large quantities of sand are needed repeatedly to maintain the beach

    • Can kill organisms if taken sand taken from the seabed

    • Very expensive

• Slope stabilisation: marram grass is planted on sand dunes; its long roots bind and hold dunes together

  • Benefits:

    • Relatively cheap

    • Minimal impact on the environment, enabling wildlife to live there

    • Prevents mass movement by increasing the strength of the slope

  • Costs:

    • Can be damaged by storm waves

    • Areas may have to be zoned off from the public so that the newly planted grass is not trampled on, which may be unpopular

• Strategic realignment: removing an existing defence and allowing the land behind it to flood or erode naturally

  • Benefits:

    • Over time the land will become marshland, creating new habitats

      • Good for environment

    • New natural landforms (eg. salt marshes) act as natural defences

    • No maintenance costs

    • Looks natural (good for tourism)

  • Costs:

    • People may disagree over which land should be allowed to flood

    • Loss of land

    • High initial costs to breakdown and remove previous infrastructures

Give the more sustainable approaches to coastal defences

• Strategic realignment: removing an existing defence and allowing the land behind to flood, creating new habitats which can act as natural defences that adapt naturally to sea level rise for the land behind the flooded area

• Do nothing approach: no new coastal defences are built and erosion and flooding are dealt with as they occur; it doesn’t cost anything, but infrastructure may be lost and people may be forced to migrate away if the coast continues to retreat

  • Usually because the cost of new management is greater than the value of the land that it is protecting

What is ICZM?

Integrated coastal zone management; is a sustainable and holistic strategy used to manage whole coastal systems (as it recognises that different parts of the coastline affect other parts).

It balances:

• Human activity

• Economic development

• Environmental protection

Is coastal management planning that:

• aims to protect the coast as a whole

• long term (can be adapted to future needs and changes)

• while balancing and taking everyone’s interests into account (all stakeholders)

This makes it easier to find solutions that people can agree on.

Describe the upper course of the river

Name the features it has

The river starts as many tributaries usually in mountainous or upland areas; rivers have the lowest energy due to limited discharge.

Vertical erosion dominates, deepening the river valley.

The channel has:

• steep gradient

• small discharge

• shallow depth

• narrow channel with steep sides

• quite fast velocity

• large, angular load

  • large bedload

• steep, v-shaped valleys

• rough channel bed

  • large amounts of friction

• vertical erosion

Transportation mainly occurs via traction and saltation due to the large size of sediment

Features: Waterfalls, interlocking spurs, steep v-shaped valleys

Describe the middle course of the river

Name the features it has

The river gains more energy as discharge increases with added tributaries; lateral erosion becomes dominant, widening the channel.

The channel has:

• Less steep gradient

• Large discharge

• Wider, deeper channel

• Greater velocity

• Smaller, smoother load due to friction

• Smoother channel bed

  • Lower levels of friction

• Gentle, sloping valley sides

• Lateral erosion

Features: meanders, floodplains

Describe the lower course of the river

Name the features it has

The river has its greatest discharge, making it powerful and have lots of energy; the gradient is very gentle, and deposition becomes the dominant process.

The channel has:

• gentle gradient

• very large discharge

• very deep

• very wide, almost flat valley

• carries fine, suspended sediment and alluvium

• flat riverbed, gentle sliding sides

• very fast velocity

• very smooth channel bed

  • minimal friction

• mainly deposition

Features: floodplains, levees, deltas, broad flat valleys

State the dominant process in the upper course, middle course and lower course

Upper course: vertical erosion

Middle course: mixture of deposition and lateral erosion

Lower course: deposition

• As it slows down and loses energy because the land becomes very flat

Describe how vertical and lateral erosion occur

Vertical erosion: rough, angular particles are scraped along the riverbed, causing intense downward erosion due to steep gradient

Lateral erosion: when the river flows at a lower gradient, the load collides into the sides of the river, eroding it sideways

What course of the river is the velocity of the water quickest in, why?

Lower course

The more friction that occurs with the water and the riverbed, the more the water is slowed down; in the middle and lower courses of the body of water receives less relative friction due to the greater volume of the water; this therefore makes the channels wider and deeper as the water has greater erosional power

Describe how a named river’s landscape changes between its upper course, middle course and lower course

Named river: River Tees

Source from the Pennines mountains, flows eastwards.

Upper course:

• Narrow and shallow channel

• Uneven river bed; high friction slows the water flow

• Large, angular boulders

• Vertical erosion has shaped a steep river gradient and high valley sides; waterfalls and interlocking spurs

Middle course:

• Valley widens and river sides become more gently sloped

• Lateral erosion replaces vertical erosion, creating meanders

• Many tributaries join (eg. River Lune, River Greta) leading to a notable increase in water volume

Lower course:

• Gentle gradient

• Deposition is the main process; forms oxbow lakes and levees

• The Tees mouth forms a large estuary

How to calculate river discharge and what is it measured in

River discharge is the volume of water that flows in a river per second

discharge = cross sectional area x velocity

m³/s or cumecs

Explain the water transportation processes

• Traction: large particles like boulders are pushed along the riverbed by the force of the water

• Saltation: Pebble-sized particles are bounced along the riverbed by the force of the water

• Suspension: small particles like silt and clay are light enough to float so are carried along by the water

• Solution: soluble materials are dissolved in the water and are carried along

Describe how waterfalls and gorges are formed

Waterfalls and gorges are erosional landforms

• Waterfalls from when a river flows over a band of hard rock that overlies a band of soft rock

• The soft rock is eroded more quickly than the hard rock, creating a step in the river

• As water goes over the step it erodes more and more of the softer rock

• A steep drop is created (the waterfall)

• The hard rock is eventually undercut and left suspended in the air until it becomes unsupported and collapses

• The collapsed rocks are swirled around at the foot of the waterfall where they continue to erode the softer rock by abrasion, creating a deep plunge pool

• Erosion continues to undercut the hard rock, creating another overhand again further upstream

• This continual process of overhang collapsing causes the waterfall to retreat upstream over time; as the waterfall retreats it leaves behind a gorge

Describe how v-shaped valleys are formed

• Vertical erosion occurs in the upper course of the river

  • Due to force of gravity scraping load along riverbed

• This cuts down riverbed and deepens the channel

• Weathering weakens the valley sides

• Mass movement leads to material from the weakened valley sides collapsing into the river forming a steep v-shaped valley

• River transports this material away, leaving behind steep valley sides

Describe how interlocking spurs are formed

Interlocking spurs are an erosional landform

• In the upper course of a river, most of the erosion is vertical

• This creates steep-sided v-shaped valleys

• When the river encounters hard rock (in the spurs), it is not powerful enough to erode it, so are forced to wind around it

• So high hillsides project into the valley from alternating sides as the river winds around them

Describe how meanders are formed

Meanders are formed by both erosion and deposition; they are bends in the river usually found in the middle course

• Rivers have a helicoidal flow, meaning that the water travels fastest on the outside of the bend and travels slower on the inside of the bend

• This means that more erosion occurs on the outside of the river bend, forming river cliffs

• More deposition occurs on the inside of the river bend, forming slip-off slopes

• Over time this creates bends in the river

Describe how ox-bow lakes are formed

Ox-bow lakes are formed from meanders

• As erosion continues on the outer bend, the outer bends of a meander become closer

• This leads to the formation of a meander neck

• Eventually the river breaks through the neck (usually during a flood as there will be greater river discharge and thus more erosional power) and the river flows along the shortest course

• The flow of water at entry and exit of the meander will be slower, leading to deposition

• This deposition eventually separates the meander from the main river, creating the separate ox-bow lake

Describe how floodplains are formed

Flood plains are depositional landforms; they are flat areas of land that flood

• As river flows, it erodes outer banks, widening the river valley

• When a river floods, the water overflows onto the surrounding land

• The water loses velocity, causing it to deposit some of its load

• The deposition of sediment like silts make the floodplain fertile

• Layers of sediment build up the river plain after each flood, increasing its height and creating a flat, fertile floodplain

Describe how levees are formed

Levees are depositional landforms; they are natural embankments

• When a river floods, the water overflows onto the surrounding land

• As the water loses its velocity, it deposits some of its load

• The heaviest material is deposited closest to the river channel as it gets dropped first when the river slows down

• Over time the deposited material builds up, creating levees along the edges of the channel

Describe how deltas are formed

Deltas are depositional landforms; they are plains made up of material deposited by a river at its mouth

• When a river meets the sea or a lake, they are forced to slow down

  • due to increased friction and resistance from the standing water

• This means that the water is forced to deposit the material that it’s carrying

• If the material is not washed away (eg. by the sea), the layers of sediment build up

  • Deposits material faster than it can carry it away

• This causes the main channel to become blocked, causing the river to split into many smaller channels (dstributaries)

• Eventually the material builds up so much that low-lying areas of land (deltas) are formed

How to identify the direction that rivers flow from a map?

Rivers flow from high gradient to low gradient; using contour lines (the closer together the contour lines, the higher the gradient) and height values it can show the height of land and thus the direction of the river

How to give evidence that a river is in its upper/lower course on a map?

Upper course:

• Nearby land is high

• Waterfalls are marked on maps

• River crosses lots of contour lines in a short distance (shows it has a steep gradient)

• The river is narrow (thin blue line)

• Counter lines are very close together, meaning that the valley floor is narrow

Lower course:

• Nearby land is low

• River doesn’t cross any counter lines, very gentle gradient

• River meanders, ox bow lakes

• River is wide (thick blue line)

Explain how physical factors impact river landscapes and sediment load

Climate, geology, slope processes

• Climate:

  • Rivers in wetter climates have higher discharge as there is more water entering the river channel;

    • high discharge increases rate of erosion, adding more material to the river’s load

    • also shapes the landscape, forming v-shaped valleys in the upper course (vertical erosion) and wide, flat flood plains in the lower course (lateral erosion)

    • transportation increases as the river will have more energy to carry material

  • Stormy/ rainy climates increase weathering, which increase the river’s sediment load

• Geology:

  • Rivers flowing through hard rock have a slower rate of erosion because hard rocks are more resistant; this means that the river will have a lower sediment load

  • Areas with softer rocks will experience more erosion, adding more material to the river’s sediment load

  • Waterfalls form when there’s a layer of soft rock over hard rock

  • Interlocking spurs form when softer rock is eroded first, leaving areas of harder rock sticking out

• Slope processes

  • Mass movement can add large amounts of material to the river’s load

  • Steep slopes increase the movement of material down the slopes

  • Steep slopes encourage rapid surface runoff, leading to increased erosion and a higher sediment load

  • Gentle slopes slow down water flow, encouraging rivers to deposit their load

What do storm hydrographs show?

The changes in river discharge around the time of a storm

Explain the four features of a storm hydrograph

• Peak discharge; highest discharge in the period of time

• Lag time; the delay between peak rainfall and peak discharge

• Rising limb; the increase in river discharge as rainwater flows into the river

• Falling limb; the decrease in river discharge as the river returns to its normal level

Name and explain how physical factors can impact storm hydrographs (5)

• Geology; water cannot infiltrate impermeable rocks, so this increases surface runoff which decreases lag time

• Soil type; impermeable soils cannot absorbs as much water as permeable soils, so this increases surface runoff which decreases lag time

• Slope; the steeper the slope the less infiltration (as the angle of the land forces the water to move faster, giving it less time to absorb) which increases surface runoff

• Drainage basin type; circular drainage basins have shorter lag times as all points are roughly equidistant to the river, so water reaches the main river channel at the same time. Whereas, in a narrower basin, water from the far end of the basin takes a long time to reach the main channel

• Antecedent conditions; previously wet or very cold conditions can increase surface runoff as the water cannot infiltrate saturated or frozen soil

What is a drainage basin?

The entire area of land where all precipitation collects and drains into

How do human activities change river landscapes which alter storm hydrographs

Humans can change land use by: urbanisation, deforestation

• Urbanisation

  • Water cannot infiltrate through impermeable surfaces (eg. concrete, tarmac), so there is greater surface runoff

  • Gutters and drains quickly take runoff to rivers, which rapidly increases discharge, increasing peak discharge

• Deforestation

  • Trees take up water from the ground and store it which reduces surface runoff; therefore cutting down trees increases surface runoff which causes more water to enter the river channel

• Climate change

  • Led to more extreme and frequent weather events, meaning that antecedent conditions are usually saturated, so land cannot absorb as much rainfall leading to more surface runoff

Explain how physical factors and human activities have caused river flooding on a named river

Named river: River Tees

The River Tees is prone to flash flooding

Physical factors:

• Surrounded by impermeable rocks (eg. shale), so water cannot infiltrate

• Surrounded by high slopes in the upper course as it flows through a steep, V-shaped valley in the North Pennines

• Source is in Pennines, high altitude so experiences frequent, heavy rainfall - antecedent conditions are usually also saturated

Human factors:

• In the lower course, Tees Barrage built to control river flow to prevent flooding

• Lower Tees estuary is very industrialised (river supports large scale production and chemical works), lots of impermeable concreted land, increasing surface runoff.

  • Also very urbanised with a large population (nearby large towns like Darlington and Middlesborough)

• Sheep and cattle grazing in uplands, cause lots of deforestation — reducing interception and thus increasing surface runoff

Explain the reasons that the risk of flooding is increasing in the UK

• Increased frequency of storms

  • More periods of wet weather mean that the ground is saturated; poor antecedent conditions make it more likely to flood

  • Increasing significance of intensive rainfall events can cause significant runoff, exceeding the capacity of the river’s drainage basin and causing the river to flood more extremely

• Land use change

  • Urbanisation causes an increase in impermeable concrete surfaces, which cause rapid surface runoff

  • Deforestation, removing vegetation mean that water that would’ve been absorbed/ stored by plants now flow quickly downstream, increasing surface runoff

  • Lots of development on flood plains, as there is an increase in people living near there it means that there is an increasing flood risk to more people

Explain the threats of river flooding to people

• People can be killed or injured by floodwater

• Roads, bridges, train lines can be damaged or destroyed

• Floodwater can become contaminated with sewage, leading to a lack of clean drinking water

• Homes can be damaged or destroyed, causing people to become homeless

• Businesses can be forced to shut down because of flood damage and disrupted power supplies, leading to a loss of livelihoods

Explain the threats of river flooding to the environment

• Floodwater can become contaminated with sewage, damaging wildlife habitats

• Floodwater can become contaminated with rubbish and litter, polluting rivers and wildlife habitats

• The force of floodwater can uproot trees and plants, damaging the plants and the surrounding ecosystem

• River banks can become eroded, causing an increased risk of future river flooding and leading to huge changes to the river landscape, which can damage habitats

Name the hard engineering techniques for river management

• Flood walls

• Embankments

• Flood barriers

• Dams and reservoirs

• River straightening and dredging

Give the benefits and costs for hard engineering for river management

Flood walls, embankments, flood barriers, dams and reservoirs, river straightening and dredging

• Flood walls

  • Benefits:

    • Increase the height of river banks, allowing the river channel to hold more water

    • Long lasting and durable

  • Costs:

    • Very expensive

    • Unsightly

    • Block the view of and access to the river

    • Increased flood risk downstream

• Embankments

  • Benefits:

    • Stop the river from flowing into built-up areas when the river floods, protecting buildings and infrastructure — by increasing river capacity

    • Can be made from Earth or other natural materials, making them less unsightly

  • Costs:

    • Expensive

    • Increased flood risk downstream

    • Required maintenance

• Flood barriers

  • Benefits:

    • Prevent the river from flooding

    • Permanent flood barriers can open and close, allowing the river to flow naturally when it is not flooding

    • Can be de-mountable, so only used when needed, not disrupting visually/ the environment at all times

  • Costs:

    • Permanent flood barriers are very expensive

    • Permanent flood barriers need constant maintenance

    • De-mountable flood barriers may not be put up in time

• Dams and reservoirs

  • Benefits:

    • Provides reliable water supply

    • Hydroelectric power

    • Water can be held back during rainfall, preventing river flooding downstream

    • Can be used for recreation and tourism

  • Costs:

    • Very expensive to build and maintain

    • Environmental damage

      • Flooding land to form reservoirs destroys habitats and ecosystems

    • Reservoirs may displace people

    • May be visually unappealing

• River straightening and dredging (making it deeper)

  • Benefits:

    • Reduces flood risk locally as there is faster water removal from an area

    • Improved navigation for boats

  • Costs:

    • Increased flood risks downstream

    • Increased erosion (as moves faster with more energy)

    • Environmental damage (eg. meander habitats are destroyed)

    • Artificial and unnatural look

Name the soft engineering techniques for river management

• Flood plain retention

• River restoration

• Afforestation

Give the costs and benefits of soft engineering for river management

• Flood plain retention

  • Allows floodplains to naturally flood, restricting building developments in these areas to reduce flood risks downstream

    • Benefits:

      • Helps slow the floodwaters down and maintain the flood plain’s ability to store water

      • No money has to be spent on building flood defences

      • Allows natural ecosystem to remain natural and thrive

    • Costs:

      • Restricts development on that area

      • Cannot be used in urban areas

• River restoration:

  • Returns altered rivers to their natural state

    • Benefits:

      • Restores natural habitats, allowing the ecosystem to thrive and encouraging biodiversity

      • Very little maintenance required

      • Improves water quality

      • Reduces flood risk (by allowing flood plains to restore and work to absorb water naturally)

      • Improves natural visual aesthetics

    • Costs:

      • High initial costs

      • May lead to a loss of land (for urban/ industrial use), which can lead to land conflicts

      • Can increase flood risk if nothing is done to prevent major flooding

• Afforestation

  • Benefits:

    • Reduces surface runoff by increasing interception and infiltration, lowering flood risk

    • Environmental benefits

  • Costs:

    • Takes a long time to be effective and trees take a long time to grow

    • Land use conflict

    • Limited impact in extreme floods as soil can become saturated

Explain one reason why sedimentary rocks are usually eroded faster than igneous rocks.

More bedding planes/joints (1) so more access for water etc. (1)

Chemically less resistant to solution (1) for example chalk and limestone s (1)

Suggest one reason why only a small percentage of the Scottish coastline is being protected.

Much of the coastline is made up of hard, resistant rocks (1) so erosion rates are very low without protection (1)

Much of the coastline is very lightly populated (1) making protection expensive and pointless (1)

There is a great deal of coastline to protect (1) so only a small proportion is likely to need and/or warrant protection

Explain how coastal erosion processes create cliffs.

Waves erode the coastline with hydraulic energy and abrasion (1)

exploiting weaknesses in the structure of the rocks (1)

leading to the undercutting of the cliff (wave cut notch)(1)

leading to rockfall and/or slumping due to gravity (1)

development of cliffs and their retreat over time (1)

these processes can be exacerbated by weathering (1)

If asked about the shape of the river valley, what should you refer to?

• Gradient

• Shape

of the land either side of the river channel

Name the four types of coastal management policies

• Hold the line

• Advance the line

• Do nothing approach

  • Includes leaving current management

• Strategic realignment