Physical landscapes in the UK - section c

Question 1

what is weathering and erosion

Answer 1

weathering is where rocks are broken down where they are
erosion is when rocks are broken down and carried away by something

Question 2

what is freeze-thaw weathering

Answer 2

It happens when the temp alternates above and below 0*c. Water fills the cracks of rock and eventually freezes (when water freezes it expands) which puts pressure on the rock. One the water thaws it contracts which releases the pressure on the rock. Repeated freezing and thawing widens the crack into the rock breaks up.

Question 3

What is chemical weathering

Answer 3

Rainwater contains dissolved carbon dioxide making it a weak carbonic acid. Carbonic acid reacts with the rock that contains calcium carbonate so the rock is dissolved by the rainwater

Question 4

what is mass movement

Answer 4

its the shifting of rocks and loose materials down a slope and can cause coasts to retreat rapidly. Its more likely to happen when the material is full of water as water acts as a lubricant and makes the rock heavier. When material shifts it can create a scarp (steep cut in slope).

Question 5

Explain destructive and constructive waves

Answer 5

When wind blows over the surface of the sea it creates waves. The greater the fetch ( the distance the wind blows over the sea) the greater the wave. Storms can cause storm surges where the sea level is temporary risen caused as strong winds push water onshore.
Destructive waves erode the coast:
- high frequency and high and steep
-Their backwash is more powerful (water moving down the beach) than their swash (water moving up the beach) so material is removed.
Constructive waves deposit material:
-low frequency and are low and long
-swash is more powerful then backwash

Question 6

what three ways do waves wear away coasts.

Answer 6

Hydraulic power - waves crash against rocks and compress the air in their cracks this put pressure on the rocks. repeated compression widen the cracks and breaks the rock off
Abrasion - eroded particles in the water scrape and rub against rock removing small pieces.
Attrition - eroded particles in the water collide, break into smaller pieces and become more rounded

Question 7

Explain longshore drift

Answer 7

waves follow the direction of the mot common wind they usually don’t hit the coast at a right angle. The swash carries material up the beach in the same direction as the waves but the backwash carries material down the beach at a right angle eventually creating a zig zag of material over time.

Question 8

Explain traction

Answer 8

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

Question 9

explain saltation

Answer 9

pebble -sized particles are bounced along the sea bed by the force of the water

Question 10

explain suspension

Answer 10

small particles like silt and clay are carried along in the water

Question 11

explain solution

Answer 11

soluble materials dissolve in the water and are carried along

Question 12

what is deposition and what causes it

Answer 12

deposition occurs when water carrying material loses energy and slows down.
-coasts build up when the deposition is greater then the erosion
the amount of material deposited is increased when:
-there lots of erosion elsewhere on the coast (more material available)
-lots of material is transported into the area
-constructive waves as they drop more then remove.

Question 13

what is a discordant and concordant coastline

Answer 13

discordant coastline is made up of alternating bands of hard and soft rocks at right angles to the cost
concordant - the alternating bands of rocks it parallel to the coast

Question 14

How are headlands and bays formed

Answer 14

Headlands and bays are formed on concordant coastline so the erosion happens faster on the softer rock than the hard rock. This causes the soft rock to be eroded faster creating a bay with a gentle slop whereas the hard rock is eroded slowly meaning it juts out forming a headland with steep sides.

Question 15

How are headlands eroded in to caves, arches and stacks

Answer 15

The resistant rocks that form a headland often have weaknesses likes cracks so when waves crashes against these cracks hydraulic action and abrasion erodes it. repeated erosion causes a cave to form. Then the cave is further eroded until it breaks through creating an arch. The rock that supports the arch continues to be eroded until it collapse leaving a stack (an isolated rock separate from headland).

Question 16

How are cliffs eroded to form wave-cut platforms.

Answer 16

Erosion happens at the foot off a cliff over time eventually creating a wave-cut notch. This is the enlarged over time until the rock above the notch is unstable and collapses. The fallen material is then washed away and a new notch begins to form. After repeated collapsed the cliff retreats leaving behind a wave-cut platform

Question 17

How are beaches formed

Answer 17

Beaches are formed by constructive waves and can form either a sand beach or a shingle beach.
Sand beaches are created by low energy waves that are flat and wide. Sand particles are small so the weak backwash can move them back down the beach, creating a long gentle slope.
Shingle beaches are created by high energy waves that are steep and narrow. Sand particles are washed away but larger shingles are left behind. The shingles particle build up to create a steep slope

Question 18

How is a spit formed

Answer 18

Spits form at sharp bends at rivers. Long shore drift transport sand and shingle past the bend and deposits it in the sea. Strong winds and waves can curve the end of the spit creating a recurved end. The area behind the spit is sheltered from waves so material can accumulate over time. Over time the sheltered area can become a mud flat or saltmarsh

Question 19

How are bars formed

Answer 19

A bar forms when a spit joins two headlands together. The bay behind the bar is cut off from the sea meaning a lagoon behind the bar can form. Offshores bars can form if the coast has a gentle slope - friction with the sea bed causes waves to slow down and deposit sediment offshore creating a bar that is not connected to the coast.

Question 20

How is a sand dune formed

Answer 20

When sand is deposited by longshore drift is moved up the beach by wind. Obstacles cause the wind speed to decrease so sand is deposited, forming small embryo dunes. Embryo dunes are then colonised by plants e.g. marram grass. The roots of the plants stabilise the sand encouraging more sand to accumulate their this form foredunes and eventually mature dunes. New embryo dunes form in front of stabilised dunes. Dune slacks (small pools) can form in hollows between dunes

Question 21

what is hard engineering

Answer 21

man-made structure built to control flow of the sea and reducing flooding and erosion

Question 22

what is soft engineering

Answer 22

Schemes set us using knowledge of the sea and its processes to reduce the effects of flooding and erosion

Question 23

What is a sea wall and its benefits
hard engineering

Answer 23

A wall made up out of a hard material like concrete that reflects waves back to the sea.
It prevents erosion of the coast and acts as a barrier to prevent flooding. However it creates a strong backwash that erodes under the wall and its expensive to build and maintain

Question 24

What is gabions and its benefits
hard engineering

Answer 24

A wall of wire cages filled with rocks usually built at the foot of cliffs. It absorbs wave energy reducing erosion and flooding. Its also fairly cheap. However they are ugly and the wire cages can corrode over time.

Question 25

What is rock armour and what is its benefits
hard engineering

Answer 25

Boulders that are piled up along the coast. It absorbs wave energy, reducing erosion and flooding and it cheap. However the boulders can be moved by strong waves so may need to be replaced.

Question 26

What is Groynes and its benefits
hard engineering

Answer 26

Wooden or stone fences that are built at right angles to the coast. They trap material transported from longshore drift. They create wider beaches which slow waves. This gives better protection from their flooding and erosion there also cheap. However They starve beaches further down the coast making them narrower. Narrow beaches don’t protect the coast very well leading to greater erosion.

Question 27

What is beach nourishment and reprofiling and its benefits
soft engineering

Answer 27

Sand and shingle from elsewhere (sea bed) are transported to the upper part of beaches. This creates wider beaches which slow waves giving greater protection from flooding and erosion. However its expensive has to be repeated and taking material from seabed can kill organisms like sponges and coral.

Question 28

What is dune regeneration and its benefits
soft engineering

Answer 28

Creating or restoring sand dunes by planting vegetation or nourishment to stabilise the sand. This creates a barrier between land and sea and absorbs waves energy preventing flooding and erosion. Stabilisation is cheap. However the protection is limited to a small area nourishment is very expensive.

Question 29

What is managed retreat.

Answer 29

Allowing the sea to flood the land behind which will create a marshland overtime which then protects the land behind it from flooding and erosion. Its cheap and easy and doesn’t need maintaining and can also create new habitats for animals and plants. However it can cause conflicts e.g. flooding farmlands affects farmers.

Question 30

What is a rivers course

Answer 30

-The path of a river as it flows down hill is called its course
-rivers have steep upper course, a gently sloping middle course and a almost flat lower course
-rivers form valleys and channels as they flow downhill
-They erode the landscape and transport eroded material to somewhere further down the course.
The shape of a valley and channel changes along the river depending on weather erosion or deposition is the dominant process.

Question 31

what is the upper course like

Answer 31

steep gradient
v-shaped valley, steep sides, narrow, shallow channel

Question 32

What is the middle course like

Answer 32

medium gradient
-gently sloping sides, wider deeper channel

Question 33

What is the lower course like

Answer 33

Gentle gradient
Very wide, almost flat valley.
Very wide and deep chaneel

Question 34

what is vertical erosion

Answer 34

this deepens the river valley and channel making it v-shaped. Its 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.

Question 35

What is lateral erosion

Answer 35

Widens the valley and channel during the formation of meanders. dominant in the lower and middle course of the river.

Question 36

what is solution

Answer 36

river water dissolves some type of rock e.g. chalk

Question 36

what is solution

Answer 36

river water dissolves some type of rock e.g. chalk

Question 37

what reasons do cause rivers to slow and deposit materials

Answer 37

-the volume of water falls
-the amount of eroded material increases
-the water is shallower
-the river reaches its mouth

Question 38

how are waterfalls and gorges formed

Answer 38

Waterfalls form where a river flows over an area of hard rock followed by an area of soft rock. The softer rock is eroded by hydraulic action and abrasion more then the hard rock is eroded creating a step in the river. The river continues to flow over the stock continuing to erode the soft rock until eventually a steep drop is created which is called a waterfall. The hard rock is also eventually undercut by erosion becomes unstable and collapse. The collapsed rock erode the soft rock at the bottom of the waterfall by erosion eventually creating a plunge pool. Over time more undercuts happen and collapse so the waterfall retreats leaving behind a steep-sided gorge.

Question 39

how is a interlocking spurs formed

Answer 39

In the upper course of the river most of the erosion that happens is vertical creating steep v-shaped valleys. The river lacks power at the upper course to erode laterally meaning the river winds around high hillsides that get in their way. The hillsides that interlock with each other called interlocking spurs

Question 40

How is a meander formed

Answer 40

A meander is a large bend in a river. It caused by the current of a river being faster on the outside because the channel is deeper. Because of this the hillside is eroded much more forming a river cliff. The eroded material is then deposited id deposited on the inside of the bend where the water is slower because its shallower. This forms a slip off slope.

Question 41

How is a oxbow lake formed from a meander

Answer 41

Over a long period of time meanders can get bigger and form a ox-bow lake. Erosion causes the outside bends to get closer until their is only a small part of land separating them called the neck. Eventually the neck is eroded so the river follows the shortest course instead of the meander. Deposition eventually cuts of the meander forming a ox-bow lake.

Question 42

what is a flood plain

Answer 42

a flood plain is a wide valley floor either side of a river which occasionally floods. The rivers flood the water slows down and deposits the material its transporting building up the flood plain. Meanders also widen as they move across floodplains laterally and they also migrate downstream.

Question 43

how are levees formed

Answer 43

levees are natural embankments along the edges of a river channel. During a flood when material is deposited the heavy material is deposited first meaning it gets dropped near the river channel. This material builds up creating a levee.

Question 44

what is a estuaries

Answer 44

Estuaries are found at river mouths. The land is close to the sea and the river valley is at its widest. The water here is tidal so the river level falls and rises. When the water floods over the banks of the river it carries slit and sand onto the valley floor. As the tide reaches its highest point the sediment is deposited because the water slows. Over time more mud builds up creating large mud flats. at low tide the mudflats are exposed.

Question 45

what is river discharge

Answer 45

the volume of river water flowing per second
m3/s

Question 46

how does heavy rainfall increase flooding risk

Answer 46

water arrives to quickly to infiltrate, so theres lots of surface runoff, which increases discharge

Question 47

how does geology (rock type) increase flood risk

Answer 47

clay soils and some rock is impermeable (don’t allow infiltration) so runoff is increased.

Question 48

how does prolonged rainfall increase flood risk

Answer 48

prolonged rainfall can saturate the soil. This means further rainfall cannot infiltrate increasing surface run off.

Question 49

relief (changes in land height)

Answer 49

if a river is in a steep-sided valley the water will reach the river quicker as it flows faster this will increase discharge.

Question 50

how does land use increase flood risk

Answer 50

Buildings are impermeable and buildings are surround by impermeable roads increasing surface run off. This run off is collected my manmade drains which quickly transports runoff to river increasing the river discharge.
Trees also intercept rainfall on their leaves which then evaporates they also soak up water and store it. So cutting down trees decreases the amount of water taken up increasing surface run off so discharge increases.

Question 51

what is a dam and reservoir and what are benefits
hard engineering

Answer 51

A dam is a barrier built across rivers. A reservoir is a article lake that forms behind a dam. Its good because reservoirs store water, control water flow and prevent floods downstream. They can also be used to generate hydroelectric power. However they are expensive reservoir can flood existing settlements. Material is deposited in reservoir not along river course so downstream farmland can become less fertile.

Question 52

how does channel straightening reduce flooding or its effects
hard engineering

Answer 52

meanders are removed by building straighter artificial channels. This means that water will leave the area more quickly rather than building up so it reduces flooding chances. However flooding may happen downstream instead. Faster moving water may also cause erosion downstream.

Question 53

how does embankments reduce flooding
hard engineering

Answer 53

Raised walls are built along river banks. The river can hold more water so floods are less frequent. However they are quite expensive and theses a risk of serve flooding if the water rises above or the embankments break.

Question 54

how does flood relief channels reduce flooding
hard engineering

Answer 54

Channels are built to divert water around build up areas or to divert excess water it the river levels get too high. The gates on the channels mean that the release of water can be controlled, reducing flood. There will be increased discharge where the relief channels joins another river which could cause flooding in that area.

Question 55

how does flood warnings and preparation
soft engineering

Answer 55

The incoming flood is announced via radio etc so buildings and homes can be altered to minimise flood damage. Supplies can also be gathered. Warnings give people time to move valuables and prepare or evacuate which reduces flood damage.
However:
-doesn’t stop the flood
-people may not have access to warnings
-modifying buildings can be expensive

Question 56

How does flood plain zoning reduce flood risk
soft engineering

Answer 56

Restrictions that prevents buildings being built on flood plains that are likely to be affected by floods. This is good because less damaged is created and less impermeable materials are created. However expansion in urban areas are limited and this doesn’t help existing buildings.

Question 57

Planting trees
soft engineering

Answer 57

Planting trees in the river valley increase the interception of rainfall leading to greater lag time.
This is good because discharge and flood risk is decrease, vegetation prevents soil erosion and habitats. However less land is available for farming and building.

Question 58

River restoration
soft engineering

Answer 58

making the river more natural so that the flood plain can flood naturally. Discharge is decreases so less chance of flooding downstream. Plus little maintenance and good for environment. However local flood risk can increase.