The UK's Evolving Physical Landscape Flashcards
(138 cards)
1
Q
How did geology influence the physical landscape of the UK?
A
- 250m-300m years ago, the UK was covered by tropical seas.
- Calcium carbonate crystallised around the fragments and cemented them together.
- Later other rocks strata were deposited on top of the limestone
- As the fish died, skeleton would fall and compact beneath into rock.
2
Q
How did glaciation influence the physical landscape of the UK?
A
- As the Pennines eroded, rivers eroded into them created v-shaped valleys.
- Altering river valleys, making them deeper and wider making them u-shaped troughs.
- As they melted the glaciers left features.
3
Q
How did tectonic processed influence the physical landscape of the UK?
A
- When uplift, rocks snap and move along faults in a series of earthquakes.
- Convection currents beneath tectonics uplifted rocks from below the sea which created land.
- 3 major tectonic process over 300m years.
- Each movement which happened disturbed the strata causing the rocks to tilt.
- Uplift can raise more parts than others.
4
Q
What are the features of an igneous rock?
A
- Formed by the cooling and solidification of magma/molten.
- Formed beneath the Earth’s surface or on its own as lava.
5
Q
What are the features of a sedimentary rock?
A
- Formed through deposition and solidification of sediment.
- Most commonly found in water.
- Sometimes contain fossils.
6
Q
What are the features of a metamorphic rock?
A
- Been changed by extreme heat and pressure causing the rock to have physical or chemical change.
7
Q
Features of chalk.
A
- Purer, younger form of limestone.
- Very porous.
- Sedimentary
8
Q
Features of limestone.
A
- Permeable.
- Consists pf crushed corals that were formed in tropical seas.
- Sedimentary.
9
Q
Features of clay.
A
- Formed from muds.
- Soft and crumbly.
- Very weak.
- Found near rivers or sea.
- Sedimentary.
10
Q
Features of granite.
A
- Formed from cooling magma.
- Contains glass crystals, white and skinny black crystals.
- Very resistant
- Igneous.
11
Q
Features of schist.
A
- Formed by further metamorphic of slate when it is partly melted and solidified.
- Very resistant.
- Metamorphic.
12
Q
Features of slate.
A
- Formed from heated muds or shale.
- Could be sedimentary.
- Very resistant.
- Metamorphic.
13
Q
Features of an upland area in the UK - Snowdonia.
A
- Igneous rock.
- Slates and shales.
- 600m years.
- Very resistant.
- Heavy relief.
- Black and heavy rocks.
14
Q
Features of a lowland area in the UK - London.
A
- Sedimentary.
- Sands and clays.
- 70million.
- Weak resistance.
- Relief becomes shale.
- Soft and crumbly rock.
15
Q
How have active volcanoes shaped the land - tectonic process?
A
- 520M years ago the land that the UK is on now was closer to a plate boundary than now.
- Forced magma through the crust which cooled to from igneous rocks.
16
Q
How have plate collisions shaped the land - tectonic process?
A
- Caused rocks to be folded and uplifted forming mountain ranges - these are now probably uplands.
- Intense heat and pressure formed metamorphic rocks.
17
Q
How have plate movements shaped the land - tectonic process?
A
- 345-280M Britain was in the tropics.
- Higher sea levels meant it was underwater.
- Carboniferous limestone formed in warm shallow seas which can now be seen in uplands of peak district.
18
Q
When the UK was covered in mostly ice, how did it happen over this 2.6M period?
A
- Very powerful meant it was able to erode the landscape carving out u-shaped valleys in upland areas.
- Glaciers deposited lots of materials as they melted.
- Landscapes formed by glacial melt water and deposits extend south of the ice sheets.
19
Q
How did weathering alter the landscape?
A
- Breakdown of rock into smaller pieces.
- Mechanical, chemical and biological.
20
Q
How did erosion alter the landscape?
A
- Wears away rock.
- During last glacial period, ice eroded the landscape.
- Rivers and sea now constantly erode the landscape.
21
Q
How did post-glacial and river processes alter the landscape?
A
- Melting ice at the end of glacial periods made rivers bigger than normal with more power to erode.
- Ice left distinctive landforms when it melted, for example, hanging valleys.
22
Q
How did slope processes erode the landscape?
A
- Include mass movements - rock falls, slides, slumps and soil creeps.
23
Q
How are physical processes affected?
A
- By climate.
- Cold climate increases the chance of freeze-thaw weathering.
- Wet climate affects the number of streams and rivers.
24
Q
What are the features of a u-shaped valley in an upland area? - Snowdonia
A
- Eroded by ice.
- Flat floor and steep sides.
- Contains a misfit river that looks too small to have created it.
25
How is a tarn formed in a upland area? - Snowdonia
- Sits in a corrie, therefore, it was hollowed out by ice in glacial times.
26
Where does freeze-thaw weathering occur in the corrie in an upland area? - Snowdonia
- Steep back wall.
| - Rocks are broken up and rock falls which forms scree slopes.
27
How does the weather affect snowdonia?
- Most rocks are impermeable when there is lots of rain so lots of streams that are eroding the sides of the corrie and forming gullies.
28
What are rivers like in lowland areas?- The Weald
- Meander on impermeable clay, widening the valley floor -
29
How can climate affect the Weald?
- Due to wet climate heavy rain can lead to flooding.
| - Overflowing river deposits slit on valley floor forming a flood plain.
30
What are dry valleys in lowland areas - The Weald?
- Valleys with no streams visible, streams flow underground in permeable chalk.
- Formed during glacial periods when the colder climate led to freeze-thaw weathering and glacial snow melt meant streams had much more water in them than they do today.
31
How have humans changed the landscape through agriculture?
- People have cleared the land to make space for farming. - Overtime hedgerows and walls have been put in to mark the fields.
32
What is an arable landscape best for in farming terms?
- Flat land with good soil is used for growing crops.
33
What is a dairy landscape good for in farming terms?
- Warm, wet areas are good as theres lots of large greasy fields.
34
What is a sheep landscape good for in farming terms?
- Harsher conditions in Uplands.
- Lack of trees in hills.
- Young trees are eaten or trampled before they get a chance to be matured.
35
How has human forestry changed the landscape?
- Management of woodland areas, used for timber, recreation or conservation.
- UK used to be covered un deciduous woodland but there is very little natural woodland left.
- Coniferous forests have been planted for timber, trees are often planted in straight lines. They don't look natural. When areas are felled the landscape is left bare.
- In some places deciduous woodland is being replanted to try to return the area to a more natural state.
- OS maps show forestry plantations and areas that are bing managed.
36
How has human settlement changed the landscape?
- Settlers needed water supply so they needed somewhere that could easily be defended or that was sheltered from wind and rain.
- Bridging points over rivers and the availability of resources.
- Most of the biggest cities are ports and industrial areas.
- Look for buildings, railways, canals and embankments to identify settlements on OS maps.
37
As settlements grew, how did they affect the landscape?
- Land was concurred over roads and buildings which affected drainage patterns.
- Some rivers were diverted through underground channels.
- Some river channels were straightened or had embankments built to prevent flooding.
38
What are the features of mechanical weathering?
- Breakdown of rock without changing its chemical composition.
- Salt weathering affects coasts.
1. Seawater gets into rock cracks.
2. When water evaporates, salt crystals form. Salt crystals form and expand which puts pressure on the rock.
3. Repeated evaporation of saltwater and forming of salt crystals widens the cracks and causes there rock to break up.
39
What are the features of chemical weathering?
- Breakdown of rock by changing its chemical composition.
- Carbonation weathering is a type and happens in wet and warm conditions
1. Seawater and rainwater have CO2 dissolved in them, making them weak carbonic acids.
2. Carbonic acids react with rock that contains calcium carbonate so the rocks are dissolved by rainwater.
40
What are the features of biological weathering?
- Breakdown of rock by living things.
| - Plant roots break down rocks by growing into cracks on their surface and pushing them a part.
41
What are mass movements and when and how do they occur?
- Shifting of rocks and loose material down a slope. It happens when the force of gravity acting on s slope is greater than the force supporting it.
- Cause coasts to retreat rapidly.
- More likely to happen when material is full of water acting as a lubricant which makes the material heavier.
42
What are the 3 types of mass movements and what do they do?
- Slides: material shifts in a straight line.
- Slumps: Material shifts with a rotation. (Rotational slumping.
- Rockfalls: Material breaks up and falls down slope.
43
How does hydraulic power erode the coast?
- Waves crash against the rock and compress the air in the cracks.
- Pressure is put on the rock.
- Repeated compression widens the cracks and makes bits of the rock break off.
44
How does abrasion erode the coast?
- Eroded particles in the water scrape and rub against the rock, removing small pieces.
45
How does attrition erode the coast?
- Eroded particels in the water smash into each other and break into smaller fragments. Their edges also get rounded off as they rub together.
46
How can the geological structure of a coastline influence the formation of erosional landforms?
- Hard rocks are more resistant so it takes longer for them to be eroded and weathered by physical processes.
- Softer rocks are less resistant which means they are eroded more quickly.
47
What are the features of discordant coastlines?
- Made up of alternating bands of hard and soft rock that are perpendicular to the coast.
- Bays and headlands are more common here because the bands of rocks are being eroded at different rates.
48
What are the features of concordant coastlines.
- Alternating bands of hard and soft rock are parallel to the coast.
- Eroded at the same time so there are fewer erosional landforms.
49
How does the UK's climate have an impact on coastal erosion and retreat?
- Temperature varies with the seasons; coldest in winter, warm through spring, hottest in summer and cool through autumn.
- Differences in temperature have an impact on processes along get coast, for example, salt weathering because water evaporates more quickly.
- Storms are very frequent, especially in winter. Strong winds give high energy, destructive waves increase Erin of cliffs. Intense rainfall can cause cliffs to become saturated creating mass movements.
- Prevailing winds in the UK are mostly warm south westerlies which bring storms from the Atlantic Ocean.
- Cold northerly winds are common.
50
How do destructive waves wear away the coast?
- High, steel and have a high frequency, 10-14 waves per minute.
- Backwash, movement of water back down the beach, is more powerful than its swash, movement of water up the beach means material is removed from the coast.
- Storms increase erosional power which can lead to increased rates of coastal retreat.
51
How are wave-cut platforms formed?
- Waves cause most erosion at the foot of the cliff.
- Forms a wave cut notch, which is enlarged as erosion continues.
- Rock above the notch becomes unstable and collapses.
- Collapsed material is washed away and a new wave cut notch starts to form.
- Repeated collapsing results in the cliff retreating.
52
How do headlands and bays form along a discordant coastline?
- Soft rocks or rocks with lots of joints have low resistance to erosion. Hard rocks with a solid structure have a high resistance to erosion.
- Form where there are alternating bands of resistant and less resistant rock.
- Less resistant rocks eroded quickly snd forms a bay.
- Resistant rock is eroded more slowly and its left out forming a headland.
53
Headlands-Caves-Arches-Stack-Stump
- Usually made up go resistant rocks that have weaknesses like cracks.
- Waves crash into the headlands and enlarge the cracks, mainly by hydraulic power and abrasion.
- Repeated erosion and enlargement of the cracks cause a cave to form.
- Continued erosion deepens the cave until it breaks through the headland forming an arch.
- Erosion continues to wear way the rock supporting the arch, until it eventually collapses.
- Forms a stack, an isolated rock thats operate from the headland.
54
Transportation of material - Longshore Drift.
- Waves follow the direction of the prevailing winds.
- Usually hit the coast at an oblique angle.
- Swash carries material up the beach, the same direction as the waves.
- Backwash carries material down the beach at right angles, back towards the sea.
- Over time, material zig zags along the coast.
55
What is deposition?
- When material is being carried by the seawater and dropped on the coast. Occurs when water carrying sediment slows down so that it isn't moving fast enough to carry so much sediment.
56
How do constructive waves deposit material?
- Waves that deposit more material than they erode.
- Low, long and have a low frequency (6-8 waves per minute).
- Swash is powerful and carries material up the coast.
- Backwash is weaker and it doesn't take a lot of material back down the coast.
57
How does deposited sediment form spits?
- Form at large bends in the coastline.
- Longshore drifts transports sand and shingle pas the bend a deposits it in the sea.
- Strong winds and waves can curve the end of the spit.
- Sheltered area behind spit is protected from waves, lots of material accumulates in this area, which means plants can grow there.
- Overtime, the sheltered area can become a mud flat or a salt marsh.
58
How does deposited sediment form bars?
- Formed when a spit joins two headlands together.
- Bar cuts off bay between the headlands from the sea.
- A lagoon can form behind the bar.
59
How can you identify caves, arches and stacks on a map?
- Caves, arches can't be seen on a map because of the rock above them.
- Stacks look like little blobs in the sea.
60
How can you identify cliffs and wave cut platforms on a map?
- Cliffs and other steep slopes are shown on maps as little black lines.
- Wave cut platforms are shown as bumpy edges along the coast.
61
How can you identify different types of beaches on a map?
- Sand beaches are shown on maps as pale yellow.
| - Shingle beaches are shown as white or yellow with speckles.
62
How can you identify spits on a map?
- Shown by a beach that carries on out to sea, but is till attached to the land at one end.
- Might also be a sharp bend in the coast that caused it to form.
63
What are direct effects on the coastline?
- Immediate result of human activities.
| - Building coastal defences will prevent erosion.
64
What are indirect effects on the coastline?
- Happen as a result of direct effects.
| - Sea defences can prevent erosion in one place but can increase erosion in another.
65
How does agricultural activity effect the coast?
- Low economic value which means its left unprotected directly effecting on coastal landscapes because the sea can erode the cliffs and shape the land.
- Changing the way farmland is used can affect the stability of cliffs; vegetation helps bind the soil together and stabilise cliff tops. Clearing vegetation from gazing land to make room for crops can expose the soil and underlying rock, leaving it vulnerable to weathering by wind and rain.
- Land is sometimes reclaimed and drained. Directly affects the coast because it reduces the natural flood barrier.
66
How does development effect the coast?
- Coastal areas are popular places to live and work, so there is often lots of development.
- Coasts with lots of settlement may have more coastal defences than other areas because people want to protect their homes and businesses which effects the coastline positively as it is protected better from erosion.
- Indirectly effects the coastline is change in transportation across the coast.
67
How does industry effect the coast?
- Coastal quarries expose large areas of rock, making them more vulnerable to chemical weathering and erosion.
- Gravel extracted from some beaches for use in the construction industry for making concrete. This has removed material from the coast and increased the risk of erosion because theres less material to protect cliffs.
- Industrial growth at ports has led to increased pressure to build on salt marshes. These areas provide flat land and sheltered water, ideal for ports. q
68
How does coastal management effect the coast?
- About protecting coastal landscapes from impacts of erosion.
- Alter sediment movement, reducing the amount of protective beach material further along the coast increasing erosion.
- Coasts defences can reduce erosion directly effecting the coast because it prevents the landscape from retreating.
69
Features of Holderness Coast East Coast of England.
- Coastline is 61KM long. Flamborough - Spurn Heads.
- Erosion causing cliffs to collapse.
- 1.8M of land is lost to the sea every year in some places.
- Rate of erosion has been over 10M per year in recent years.
- Cliffs are mostly made of boulder fly which is easily eroded, likely to slump when its wet, causing cliffs to collapse.
- Beaches are narrow meaning they don't provide enough protection for the cliffs from the sea's erosional power.
- Faces prevailing wind direction bringing waves for NE all the way from the Norwegian Sea.
- Waves increase in power a long this long distance, so the coast is battered by highly erosive waves.
- Eroded material is moved south by longshore drift.
70
What parts of Holderness are protected by Coastal Defences?
- 11KM+ is protected by hard engineering strategies.
- Towns where people live that have high-ish populations are protected (Hornsea)
- Important infrastructure - the road the B1242 - which links many of the towns and businesses along the coast.
- Gas terminal at Easington supplies 25% of the UK's and is right on the edge of the cliff.
- Groynes and seawall at Hornsea and Withernsea.
71
What problems have been caused further down the coast at Holderness?
- Groynes protect local areas but cause natural beaches to form further down. Farms and caravan parks are at risk of falling off the cliff due to erosion.
- Material produced is normally transported south, if the material is reduced in erosion and transportation increases risk of flooding in Humber Estuary because there's less material to slow the floodwater down.
- rate of coastal retreat along Lincolnshire coast has increased due to new material.
- Spurn head is at risk of being eroded away because. less material is being added to it.
- Bays are forming between protected areas and protected areas are becoming headlands which are being eroded more heavily.
- Defences are becoming more expensive.
72
How is climate change increasing risk of rising sea levels?
- Threat to low-lying and coastal areas.
- Increase in sea levels could cause higher tides that would flood coastal areas more frequently.
- Higher tides could also removed larger amounts of material from beaches.
- Could expose more of the coastline to erosion, beaches become narrower as the sea will be able to move further in land.
73
How is climate change increasing the risk of storm frequency?
- Storms give the sea more erosional power areas of hard rock will be more vulnerable to erosion and areas of soft rock are eroded more quickly.
- Sea will also have more energy to transport material.
- High energy waves can move more material for greater distances, which could lead to some areas being starved of material leaving these areas vulnerable to erosion and flooding.
- Storm surges could become more frequent and sea levels rise could cause surges to reach further inland.
74
How is coastal flooding a threat to the people?
- Low-lying coastal areas could be permanently flooded or flood often so that thy become impossible to inhabit.
- Coastal industries may be shut down because of damage to equipment and buildings.
- risk of damage to infrastructure like roads and rail networks.
- Booming tourist industry in coastal areas. Flooding and erosion can put people off visiting. Fewer tourists means businesses that rely on tourism may close, leading to loss of livelihoods.
75
How is coastal flooding a threat to the environment?
- Ecosystems will be affected because seawater has high salt content, increased salt levels due to coastal flooding can damage or kill organisms in an ecosystem. Can also affect agricultural land by reducing soil fertility.
- Force of floodwater can uproot trees and plants, and standing floodwater drowns some trees and plants.
- Some conservation areas are threatened to coastal erosion. Lagoons on Holderness coast are protected for example.
76
What is hard engineering?
- Man made structure built to control the flow of the sea and reduce flooding and erosion.
77
What is soft engineering?
- Schemes set up using knowledge of the sea and its processes to reduce the effects of flooding and erosion.
78
What is a sea wall, benefits and costs?
- Hard engineering.
- Wall made out of hard material like concrete that reflects waves back to sea.
- B: Prevents erosion of the coast, also acts as a barrier to prevent flooding.
- C: Creates strong backwash which erodes under the wall. Sea walls are very expensive to build and maintain.
79
What are groynes, benefits and costs?
- Wooden or stone fences that are built at right angles to the coast. They trap material transported by longshore drift.
- B: Create wider beaches which slow the waves. Gives greater protection from flooding and erosion. Fairly cheap defence.
- C: Starves beaches further down the coast of sans making them narrower, narrower beaches don't protect the coasts as well, leading to greater erosion and floods.
80
What is beach replenishment, benefits and costs?
- Sand and shingle from elsewhere or from lower down the beach are added to the upper part of the beaches.
- B: Creates wider beaches which slow the waves. Gives greater protection from flooding and erosion.
- C: Taking material from seabed can kill organisms like sponges and corals. Very expensive defenced and has to be repeated.
81
What is slope stabilisation, benefits and costs?
- Reinforced by inserting concrete nails into the ground and covering the slope with metal netting.
- B: Prevents mass movement by increasing the strength of the slope.
- C: Very expensive and sometimes very difficult to install.
82
What is strategic alignment, benefits and costs?
- Removing and existing defence and allowing the land behind it to flood.
- B: Over time the land will become marshland - creating new habitats. Flooding and erosion are reduced behind the Marshland.
- C: People may disagree over what land is allowed to flood.
83
How can doing nothing affect the coast?
- Nothing as it doesn't cost anything to let the coast retreat but infrastructure could be lost.
- People might be forced to move away from the retreating coastline.
84
Why do management strategies need to be sustainable?
- Making sure erosion and flooding are controlled without causing more problems elsewhere. Strategies need to be cheap to avoid conflicted about the spending of public money.
- ICZM is an approach that aims to protect the coast while taking everyone's interests into account making it easier to find solutions that people can all agree on.
- Long term approach so it can be adapted to any future needs and changes along the coastline which makes it a sustainable approach to managing the coast.
85
Features of a river.
- Path of a river as it flows downhill is called its course.
- Rivers have an upper course and a lower course.
- Rivers form channels and valleys as they flow downhill.
- Erode the landscape then transport material to somewhere where it is deposited.
- Shape of valley and channel changes along the river depending on whether erosion amor deposition is having the most impact.
- Long profile of a river shows you how the gradient changes over different courses.
- Cross profile shows you what a cross section of the river looks like.
86
Upper Course features.
- Steep gradient.
| - V-shaped valley, steep sides, narrow, shallow channel.
87
Middle Course features.
- Medium gradient.
| - Gently sloping valley sides, wider and deeper channel.
88
Lower Course features.
- Gentle gradient.
| - Very wide, almost flat valley, very wide and deeply channel.
89
How does vertical erosion change the cross profile of a river?
- Deepens the river valley making it v-shaped.
- Dominant in the upper course of the river.
- High turbulence causes the rough, angular particles to be scraped along the river bed, causing intense downwards erosion.
90
How does lateral erosion change the cross profile of a river?
- Widens the river valley during the formation of meanders
| - Dominant in the middle and lower courses.
91
River Eden features.
- North West England between the Pennines and the Lake District mountains.
- 145KM long from source to mouth.
92
Upper Course of the River Eden
- Source of the Eden is about 600M above sea level in an area of hard, resistant rock.
- Valley is steep sided due to vertical erosion and the channel has a steep gradient.
- River channel is narrow and shallow meaning the discharge is low.
- Velocity is low due to friction from rough channel sides and bed.
93
Middle Course of River Eden
- Made from soft, resistant rock which becomes easily eroded by the river meaning that the river valley becomes wider because of lateral erosion.
- Valley sides become gentle slopes and the gradient of the channel is less steep.
- River channel also becomes wider and deeper.
- Discharge increases as more streams join the main river.
- River's sediment load is made up of smaller and more rounded rocks than it was in upper course.
94
Lower Course of River Eden.
- Valley is very wide and flat.
- When near Carlisle, only a few metres above sea level.
- High velocity because there's little friction from the channels smooth sides.
- Large discharge because two other rivers join Eden in Carlisle.
- River channel is very wide and deep, Eden is 50M+ wide in Carlisle.
- Material carried by the river is fine and well-rounded, most of it is carried by suspension or solution.
95
What is freeze-thaw weathering?
- Happens when the temperature alternates above and below 0 degrees Celsius.
- Water gets into rock that has cracks.
- When water freezes it expands putting pressure on the rock.
- When water thaws it contracts, which releases pressure on the rock.
- Repeated freezing and thawing widens the cracks and causes the rock to break up.
96
What is solution?
- River water dissolves some types of rock.
97
What is traction transportation?
- Large particles like boulders are pushed along the river bed by the force of the water.
98
What is suspension transportation?
- Small particles like slit and clay are carried along by the water.
99
What is saltation transportation?
- Pebble-sized particles are bounced along the river bed by the rock of the water.
100
Why do rivers slow down and deposit material?
- Volume of water in the river falls.
- Amount of eroded material in the water increases.
- Water is shallower.
- River reaches its mouth.
101
How are waterfalls formed?
- Where a river flows over an area of hard rock followed by an area of soft rock.
- Softer rock is eroded, by hydraulic action and abrasion, more than hard rock, opening a step in the river.
- Water goes over the step and erodes more and more of the softer rock.
- Steep drop is eventually created.
- Hard rock eventually undercut by erosion, becomes unsupported and collapses.
- Collapsed rocks are swirled round at the foot of the waterfall where they erode softer rock by abrasion creating a deep plunge pool.
- Over time, more undercutting causes more collapses. Waterfall will retreat leaving a step-sided gorge.
102
What are interlocking Spurs?
- Upper course of a river most of the erosion is vertically downwards creating steep sided v-shaped valleys.
- Rivers aren't powerful enough to erode lateral, they have to wind around the high hillsides that stick out into their paths on either side.
- Hillsides that interlock with each other as the river winds around them are called interlocking spurs.
103
How are meanders formed by erosion and deposition?
- Current is faster on the outside of the bend because the river channel is deeper, so there is less friction to slow the water down.
- More erosion takes place on the outside of the bend forming river cliffs.
- Current is slower on the inside of the bend because the river channel is shallower, more friction to slow the water down.
- Eroded material is deposited on the inside forming slip off slopes.
104
How are ox-bow lakes formed from meanders?
- Erosion causes the outside bends to get closer.
- A tiny bit of land left between the bends.
- River breaks through this land usually during a flood.
- The river flows along the shortest course.
- Deposition eventually cuts off this meander which then the ox-bow lake is formed.
105
What are flood plains?
- Wide valley floor on either side of a river which occasionally gets flooded.
- When a river floods onto the flood plain, the water slows down and deposits the eroded material thats being transported making the flood plain higher.
- Meanders migrate across the floods plain making it wider. - Meanders also migrate downstream, flattening out the valley floor.
- Deposition that happens on the slip off slopes of meanders also builds up the flood plain.
106
What are Levees?
- Natural embankments.
- During a flood, eroded material is deposited over the whole flood plain.
- Heaviest material is deposited closest to the river channel, because it gets dropped first when the river slows down.
- Over time, the deposited material builds up, cresting levees along the edges of the channel.
107
What are deltas and how are they formed?
- Rivers are forced to slow down then they meet the sea or a lake causing them to deposit the material they're carrying.
- If the sea doesn't wash away the material it builds up and the channel gets blocked which forces the channel to split up into lots of smaller rivers called distributaries.
- Eventually this material builds up so much that low lying areas of land called deltas are formed.
108
What are contour lines and how do you read them?
- Orange lines drawn all over maps.
- Tell you about the height of the land in metres by the numbers marked on them and the steepness of the land by how close together they are.
- River flows from higher to lower contour lines.
109
Evidence for upper course on a map.
- Waterfalls are often marked on maps. Symbol for a cliff new black blocky lines and close contour lines which can also be evidence of waterfalls.
- Nearby land is high.
- River crosses lots of contour lines in a short distance, which means its steep.
- River's narrow.
- Contour lines are very close together and the valley floor is very narrow, means the river is in a steep-sided v-shaped valley.
110
Evidence for lower course on a map.
- Nearby land is low.
- River doesn't cross any contour lines so its very gently sloping.
- River meanders across a large flat area which is the flood plain.
- Rivers wide; thick blue line.
- River has large meanders and an ox-bow lake may be formed here.
111
How are river landscapes and sediment load affected by climate?
- Rivers in wetter climates have a higher discharge because theres more water entering the river channel.
- Higher discharge increases rate of erosion, if a river has a higher volume of water.
Has more power to erode the river banks and beds. Adds material to the river's load.
- Also shapes the landscape forming v-shaped valleys in the rivers upper course and a wide flat flood plain in the lower course.
- Transportation also increases when there's higher discharge because the river has more energy to carry material.
- Weathering increases the river's sediment load and can affect the shape of the landscape.
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How can river landscapes and sediment load affected by geology?
- Rivers flowing through areas of hard rock have a slower rate of erosion because hard rocks are more resistant meaning 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.
- Landscapes with more resistant rocks tend to have steeper valley sides, landscapes with less resistant rocks have gentle sloping valley sides.
- Waterfalls form where there is a layer of hard rock on top of softer rock.
- Interlocking Spurs from when softer rock is eroded first leaving areas of harder con sticking out.
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How can slope processes affect river landscapes and sediment load?
- Vertical erosion by rivers makes valleys steep, increasing the movement of material down the slopes.
- Mass movement can add large amounts of material to the river's load. Mass movements are more likely during cold weather and during period of intense rainfall.
- Soil creep is when soil particles move down a slope because of gravity it's caused by the expansion and contraction of the soil. Water adds weight to the soil and makes it expand causing it to move down the slope.
- When soil dries out, it contracts.
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What is river discharge?
- The volume of water that flows in a river per second.
| - Measured in cumecs - cubic meters per second (m3/s).
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How are rivers shown graphically around the time of a storm?
In storm hydrographs.
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What is peak discharge?
Highest discharge in the period of time you're looking at.
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What is lag time?
- The delay between peak rainfall and peak discharge.
- Happens because most rainwater doesn't land directly in the river channel theres a delay as rainwater gets to the channel. It gets there by flowing quickly overland called run off or by soaking into the ground.
- If more water flows as run off lag time will be reduced meaning discharge will increase and the hydrographic will be steeper become more water gets tot the river in a short space of time.
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What is the rising lamb?
- Increase in river discharge as rainwater flows into the river.
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What is the falling limb?
- The decreases in river discharge as the river returns to its norma level.
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How does geology affect the hydrographic?
- Water can't infiltrate into impermeable rocks so there's more runoff.
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How does soil type affect the hydrographic?
More permeable soils can't absorb as much water as sandy soils, which increases runoff. Shallower soils also become saturated more quickly than deeper soils.
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How does slope affect the hydrographic?
Steeper the slope, the less infiltration and the higher the runoff.
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How does the drainage basin type affect the hydrographic?
- Circular drainage basins have a shorter lag time and higher discharge than narrow basins because water reaches the main river channel at the same time. In a narrower basin, water from the far end of the basin takes a long time to reach the main channel.
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How does antecedent conditions affect the hydrographic?
- Previously wet or very clod weather can increases runoff because water can't infiltrate saturated or frozen soil.
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How does urbanisation affect the hydrographic?
- Water can't infiltrate into impermeable surfaces so there's more run off. Gutters and drains quickly take runoffs or rivers, which rapidly increases discharge.
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How does deforestation affect the hydrographic?
- Trees take up water from the ground and store it, which reduces runoff. Cutting down trees increases runoff and causes more water to enter the river channel which increases discharge.
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How do physical factors make the River Eden prone to flooding?
- Cumbria is on the west coast of the UK, facing the prevailing south-westerly winds, the climate is mild and wet.
- One of the wettest parts of the UK, often experiencing periods of intense rainfall.
- Eden is basin is bordered by the Lake District to the west and North Pennines to the east. Both these areas are made up of hard impermeable rock meaning water can't soak through then runs off into the river channel.
- Snowfall is common on higher ground in winter month and snow melt can add lots of water to the river channel in a short space of time.
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How do human activities make the River Eden prone to flooding?
- Carlisle is a large built up area and development has occurred on Eden's flood plain affecting the flood plains ability to absorb and store floodwater. Lack of soil or vegetation means there's little infiltration of rainfall, which leads to high surface runoff.
- Natural woodland and heathland have been cleared from many upland areas in the Eden basin increasing surface run off when it rains and means that more water ends up in the river channel more quickly.
- Parts of the Eden valley have been drained to make them more suitable for farming. Drainage ditches mean water flows rapidly to the river channel.
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Why is the frequency of storms increasing?
- Could be a consequence of global climate change.
- Storms are becoming more extreme, more intense rainfall is increasing the scale of flood events.
- More periods of wet weather mean that ground is saturated, making flooding more likely.
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How is the risk of UK flooding due to Land use change?
- Growth in population increases pressure to expand urban areas leading to an increase of impermeable surfaces which causes huge surface runoff.
- Removing vegetation and permeable surface means that water that would have been stored in the soil or plants and trees now flows quickly downstream.
- Lots of development are taking place on flood plains.
- Areas naturally prone and is a risk to developed areas.
- More people living on flood plains mean that there are more people at risk.
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How does flooding threaten the people?
- People can be killed or injured by floodwater.
- Roads, bridges and rail lines can be destroyed or damaged.
- Floodwater can become contaminated which can lead to a lack of clean drinking water.
- Possessions can be damaged or washed away.
- People can be made homeless due to property damage.
- Businesses may be forced to shut down because of flood damage.
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How does flooding threaten the environment?
- Floodwater contaminated with sewage or rubbish can pollute rivers damaging wildlife habitats.
- Farmland can be ruined by silt and sediment deposited after a flood.
- River banks are eroded, causing huge changes to the river landscape.
- Force of floodwater can uproot trees and plants and standing floodwater may cause those that survive the initial wave of water to die.
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How can flood walls reduce the risk of flooding?
- Artificial barriers built along river banks.
- Designed to increase the height of the river banks allowing the river channel to hold more water.
- Flood walls are very expensive and they can be unsightly and block the view of the river.
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How can embankments reduce the risk of flooding?
- high banks built along or near the river banks.
- Stop the river flowing into buit up areas during a flood protecting buildings and infrastructure on the flood plain.
- Can be made from earth or other natural materials.
- Expensive to build and a risk of severe flooding if water rises above the level of them if they break.
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How can flood barriers reduce the risk of flooding?
- Built on river estuaries
- Stop storm surges or very high tides.
- Can be shut when theres a surge forecast to prevent flooding and they can protect a large area of land.
- Very expensive and need to be maintained regularly.
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How can demountable flood barriers reduce the risk of flooding?
- Temporary protection against flooding.
- Barriers are only put up when there's a flood forecast so there's always a risk they might not be put up in time.
- Quite expensive to build but they don't spoil the loo of attractive locations.
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How can flood plain retention reduce the risk of flooding?
- Involves maintaining the rivers flood plain.
- Helps slow floodwaters down and maintain the flood plain's ability to store water.
- No money has to be spent on building flood defences, but it restricts development and can't be used in urban areas.
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How can river restoration reduce the risk of flooding?
- Involves making the river more natural so the flood plain can flood naturally.
- Less risk of flooding downstream because discharge is reduced.
- River left in natural state so theres very little maintenance required.
- Can increase local flood risk especially if there's nothing to prevent major flooding.
