Unit 1A - Our Dynamic Landscape

Question 1

Drainage Basin definition

Answer 1

A Drainage Basin is described as the area of land that is drained by a river and its tributaries.

Question 2

Why is the drainage basin system often described as an ‘open system’?

Answer 2

The drainage basin is an open system because energy and matter can be transferred across its boundaries.
Water may be evaporated forming clouds in drainage basin A. Wind blows the clouds to drainage basin B. It rains in drainage basin B.

Question 3

What is hydrology?

Answer 3

Hydrology is the study of water.

Question 4

What is a flood hydrograph?

Answer 4

A flood hydrograph is a graph which displays discharge (in cumecs) and precipitation (in mm) on the Y-axis and time (usually in days or hours) on the X-axis.

Question 5

Flood hydrograph

What is a rising limb?

Answer 5

The increase in discharge as rainwater reaches the river.

Question 6

Flood hydrograph

What is a falling limb?

Answer 6

Some rainwater is still reaching the river but in decreasing amounts.

Question 7

Flood hydrograph

What is peak discharge?

Answer 7

Highest volume of water in the river at a certain point and at a certain time.

Question 8

Flood hydrograph

What is peak rainfall?

Answer 8

The highest intensity of rainfall in millimetres.

Question 9

Flood hydrograph

What is lag time?

Answer 9

Lag time is the difference between the time of the heaviest rainfall and the maximum level and/or discharge of the river.

Question 10

‘The Water Cycle’ definition

Answer 10

The Water or Hydrological Cycle is a natural system where water is in constant movement above, on or below the surface of the earth, and is changing state from water vapour (gas), to liquid and into ice (solid).

Question 11

Definition of water table

Answer 11

The level at which saturation occurs in the ground or soil.

Question 12

Name the processes of the Water Cycle in chronological order and visualise the layout of the drainage basin.

Answer 12

1 - Evaporation
2 - Transpiration
3 - Precipitation
4 - Infiltration
5 - Throughflow
6 - Percolation
7 - Groundwater flow
8 - Surface runoff or Overland flow

Question 13

Describe each process within the Water Cycle

Answer 13

Evaporation - Water is transformed from seawater into water vapour in the atmosphere.

Transpiration - Water vapour is lost from vegetation into the atmosphere.

Precipitation - Water vapour condenses into drizzle, rain, sleet, snow and hail, and this falls towards the surface of the land.

Infiltration - Water soaks (filters) into the soil.

Throughflow - Water moves downhill through the soil.

Percolation - Water moves from the soil and into the rock.

Groundwater flow - Water moves slowly through the soil and rocks back into the sea.

Surface runoff or Overland flow - Water moves across the surface of the earth, becoming a stream, tributary or river.

Question 14

Ass 2

Describe the features of a destructive wave

Answer 14

Size - High and close together
Frequent - Up to 15 per minute
Season - Common in winter (storm waves)
Effects - Stronger backwash than swash, erodes beach

Question 15

Ass 2

Describe the features of a constructive wave

Answer 15

Size - Low and far apart
Less frequent - 6 to 9 per minute
Common in summer
Strong swash, weak backwash - Deposition

Question 16

Ass 2

What processes cause coastal erosion?

Answer 16

Hydraulic pressure - Force of the waves alone
Abrasion (Corrasion) - Sand papering action of sand and pebbles bashing and smoothing rocks at base of cliff
Solution (corrosion) - Chemical action of seawater dissolving rocks
Attrition - Rocks and pebbles hit each other, breaking up

Question 17

Ass 2

Describe some processes responsible for coastal transportation

Answer 17

Swash - Wave breaks, carrying water and sediment up the beach
Backwash - Water/sediment returns back down beach due to gravity
Longshore drift - Zigzag movement along beach, etc

Question 18

Ass 2

How does coastal deposition occur?

Answer 18

The water slows down and has less energy to carry the sediment, it is therefore dropped.

Question 19

Ass 2

Describe some of the erosional features caused by erosional processes

Answer 19

Wave cut notch - Where waves attack bottom of cliff
Cliff - Forms when unsupported rock falls into the sea
Wave cut platforms - Almost level area as cliff retreats

Question 20

What is an input in the drainage basin system, and give an example of one.

Answer 20

An input is when water is introduced or put into the system.

Precipitation

Question 21

What is a store in the drainage basin system, and give examples of some.

Answer 21

A store occurs when water is kept within the system and not moved through it.

Interception (from vegetation)
Soil moisture
Groundwater
Surface storage

Question 22

What is a transfer in the drainage basin system, and give examples of some.

Answer 22

Transfers are processes or flows within the system, where water is moved from one place to another.

Surface runoff/ overland flow
Infiltration
Throughflow
Percolation
Groundwater flow

Question 23

What is an output in the drainage basin system, and give an example of one.

Answer 23

Outputs occur in the river system when the water is carried through the river and back into the sea.

River discharge

Question 24

Definition of watershed

Answer 24

The dividing line between one drainage basin and another.

Question 25

Definition of source

Answer 25

The starting point of a river channel, where drops of water join to start a river.

Question 26

Definition of confluence

Answer 26

Where two rivers meet and join.

Question 27

Definition of tributary

Answer 27

A small river or stream which contributes to the main river channel.

Question 28

Definition of river mouth

Answer 28

The place where the river flows into the sea.

Question 29

Definition of river channel

Answer 29

The main body of water, flowing downhill.

Question 30

Definition of discharge

Answer 30

The amount of water that passes a particular point in a river at a particular time.

Question 31

What is the unit of measurement for discharge?

Answer 31

Cubic metres of water per second (Cumecs)

Question 32

How is discharge calculated?

Answer 32

The discharge of a river is the product of the cross-sectional area (depth and width, m*2) and the velocity (speed, m/sec).

Question 33

What are some of the characteristics of the upper course of the river? (Give six points)

Answer 33

• Steep gradient
• Shallow, thin river channel
• Fast flowing
• Low discharge
• Lots of erosion
• Load is mostly angular

Question 34

What are some of the characteristics of the middle course of the river? (Give six points)

Answer 34

• Less steep gradient
• River channel deepens and widens
• Water slows down
• Discharge increases
• Erosion, transportation and some deposition
• Load is mostly sub-angular

Question 35

What are some of the characteristics of the lower course of the river? (Give six points)

Answer 35

• Gentle gradient
• River is both deep and wide
• Water can be very slow
• High discharge
• Some erosion and transportation but mostly deposition
• Load is mostly rounded

Question 36

What is the load of a river?

Answer 36

The load of a river is the material that the river is carrying.

Question 37

What is a river process?

Answer 37

A river process is simply a description of something that happens in the river.

Question 38

What is river erosion?

Answer 38

Erosion happens in a river when parts of the river bed and/or river bank get eroded and are removed from the landscape.

Question 39

What are the four types of river erosion?

Answer 39

Attrition
Abrasion/corrasion
Hydraulic action
Solution/corrosion

Question 40

Definition of river attrition

Answer 40

Attrition takes place when stones that are being carried downstream knock against each other and start to wear each other down. This knocks the edges of the stones and results in smaller, rounder sized stones further downstream.

Question 41

Definition of river abrasion/corrasion

Answer 41

The force of the moving water in the river throws the stones and other eroded particles that it is carrying against the bed and banks of the river, and this dislodges more material. It works like a piece of sandpaper grinding and eroding the rocks.

Question 42

Definition of river hydraulic action

Answer 42

This is when the force of the water pounds into the river bed and banks and dislodges more material. It works a bit like a power hose.

Question 43

Definition of river solution/corrosion

Answer 43

This is when weak acid (chemicals) in the water react with the Rock and dissolves soluble minerals. It happens often in limestone areas.

Question 44

What is river transportation?

Answer 44

Transportation is when the eroded material in the river is carried from one place to another through the river system.

Question 45

What are the four types of river transportation?

Answer 45

Traction
Saltation
Suspension
Solution

Question 46

Definition of river traction

Answer 46

This is when the heaviest particles of eroded material are rolled along the river bed. Usually these stones and boulders can only be moved when the river has a large volume of water in it.

Question 47

Definition of river saltation

Answer 47

This is when some of the heavier particles are not held up in the flow of the river all of the time. Instead they may be bounced along the river bed.

Question 48

Definition of river suspension

Answer 48

As the speed of the water increases, the river is able to pick up larger particles and stones in its flow. When particles are carried along in the flow of the water and do not make contact with the river bed, they are suspended within the water.

Question 49

Definition of river solution

Answer 49

This happens when some minerals (like limestone) dissolve easily in water and the microscopic particles are held up in the solution of the water.

Question 50

What is river deposition?

Answer 50

Deposition is where the river load becomes too heavy for the river to carry and is dumped or deposited along the course of the river.

Question 51

What river landform is often found in the upper course of the river channel?

Answer 51

Waterfall

Question 52

Where does the majority of river deposition occur along the course of the river, and why?

Answer 52

Lower course, river mouth

Velocity of water decreases, less transportation

Question 53

Large areas of deposition near the river mouth are known as …

Answer 53

Deltas

Question 54

Describe the formation of a waterfall

Answer 54

• River moves from and area of hard rock (igneous) to an area of softer rock (sedimentary)
• The softer rock is eroded, creating a drop in height
• Erosional processes (Hydraulic action, abrasion/corrasion and attrition) erode the rock further (undercutting the hard rock), creating an overhang and plunge pool.
• The overhang continues to extend and the hard rock is exposed forming a ledge
• Finally, the hard rock cannot support its own weight, forms cracks and is eroded (collapses). This process repeats itself causing the waterfall to recede, forming a gorge.

Question 55

What river landform is often found in the middle course of the river channel?

Answer 55

Meanders

Question 56

In relation to meanders, what are deeper areas of water known as?

Answer 56

Pools

Question 57

In relation to meanders, what are shallower areas of water known as?

Answer 57

Riffles

Question 58

In a meandering river, what evidence suggests that the process of lateral/sideways erosion is occurring?

Answer 58

The presence of the river cliff or erosion cliff.

Question 59

On what bend of a meandering river does erosion take place and what structure does it form?

Answer 59

The outer bend

Erosion cliff or river cliff

Question 60

On what bend of a meandering river does deposition take place and what structure does it form?

Answer 60

The inner bend

Deposition beach

Question 61

On what bend of a meandering river does the fastest flow of water take place?

Answer 61

Outer bend

Question 62

On what bend of a meandering river does the slowest flow of water take place?

Answer 62

Inner bend

Question 63

On what bend of a meandering river does transportation take place and why?

Answer 63

Outer bend

Increased velocity

Question 64

On a meandering river, what material(s) is the deposition beach comprised of?

Answer 64

Sand

Shingle

Question 64

On what bend of a meandering river is the deepest depth of water found and why?

Answer 64

Outer bend

Increased velocity —> Increased erosional processes —> River bed deepened

Question 65

On what bend of a meandering river is the shallowest depth of water found and why?

Answer 65

Inner bed

Decreased velocity —> Increase deposition —> Shallow river bed

Question 66

How is an ox bow lake formed?

Answer 66

• The river is meandering as usual, with deposition taking place on the inside of the bend and erosion occurring on the outside of the bend to create river cliffs.
• Erosion continues on the outside of the bend. During a river flood, when the velocity and discharge of the river are much higher, there is more erosion and the river cuts through the neck.
• Deposition takes place and starts to block up the neck of the river. The meaner is permanently cut off from the new, straight river channel.
• The former river channel now forms an ‘ox bow lake’, where the water will gradually infiltrate into the soil and evaporate, leaving the river bed exposed and likely to be populated by surrounding plant species over time.

Question 67

What will eventually happen to the small river cliff or erosion cliff?

Answer 67

The river bank will collapse.

Question 68

What river landform is often found in the lower course of the river channel?

Answer 68

Floodplain

Question 69

What is a floodplain?

Answer 69

The floodplain is the area of land that has been covered with the silt deposited by the changing course of the river. It is essentially the area of land over which the river is likely and able to flood.

Question 70

What is the bluff line?

Answer 70

Boundary of the flood plain where higher land is.

Question 71

When the river channel floods, what material(s) is deposited close to the river bank?

Answer 71

Sand
Silt
Alluvium

Question 72

When the river channel floods, what material(s) is deposited farthest from the river banks?

Answer 72

Sand

Gravel

Question 73

How are levees formed?

Answer 73

As the river floods and continues to deposit materials across the valley floor, the largest, coarsest material will be dumped first, close to the river bank. This forms a raised bed called a levee. The levees are formed by the repeated flooding of the river. These can build up over a long period of time.

Question 74

How is land used near rivers? (Give seven points)

Answer 74

Defensive position
Drinking water
Source of power (watermills)
Water for irrigation
Silt to add nutrients to the soil (agriculture)
Easy transport (trade)
Recreation and tourism

Question 75

What are the two different types of causes of flooding in a river?

Answer 75

Physical causes

Human causes

Question 76

Name four physical causes of flooding in a river

Answer 76

1. Precipitation
2. Soil and underlying rock
3. Land use/vegetation
4. Steepness and size of drainage basin

Question 77

Name four human causes of flooding in a river

Answer 77

1. Deforestation
2. Urban growth
3. River management
4. Global warming

Question 78

Explain why precipitation is a physical cause of river flooding

Answer 78

Flooding occurs more often when there are periods of heavy rainfall over a few days. The general rule is that the more water that falls onto a drainage over a short period of time, the more rapidly the water will fill up the air spaces in the soil, and the quicker the water will be forced to run off the surface and into the river. Sometimes the worst flooding is associated with short but intensive thunderstorms. Heavy snowfalls can also cause flooding, as water is melted by a rise in temperature. If this rise in temperature is accompanied by rainfall, there can be serious flooding.

However, flooding can also happen following periods of dry weather and drought. In the summer, the soil can become baked by the sun, making it hard and the rainwater can struggle to infiltrate into the soil. The water runs across the surface and creates a flash flood, which is when the water levels in the river rise very quickly following a rain event.

Question 79

Explain why the soil and underlying rock are a physical cause of river flooding

Answer 79

Different types of soil will influence how quickly or how slowly any rainwater will infiltrate through the soil. Sandy soils are permeable and allow water to pass through quickly. Clay soils are less permeable and will stop the water from passing through, which can cause flooding at the surface and increased surface runoff at a much faster rate.

Rock type also influences the passage of water through. Some rocks are permeable (porous) and allow the water to pass through with relative ease (for example, limestone, chalk and sandstone). However, some rocks have very small pores (non-porous) and are said to be impermeable, as water does not pass through them (for example, basalt, slate and granite).

Question 80

Explain why land use/vegetation are a physical cause of river flooding

Answer 80

Another important factor that can influence flooding is how the land is used within the drainage basin. Any drainage basin that has very little vegetation will be more likely to experience flooding than areas where there is much vegetation and forests. This is because trees intercept water through their leaves and root system, and any water stored in this way will reduce the amount of water reaching the river system.

Flood levels can be affected by the levels of vegetation in an area as they increase interception, transpiration, water absorption and their roots intercept water in the through flow. These factors reduce the amount of water reaching the river system.

Question 81

Explain why the steepness and size of a drainage basin are a physical cause of river flooding

Answer 81

The size and shape of the drainage basin can also dictate if a river is more or less likely to flood. A large drainage basin means that the water will take a long time to reach the river and is less likely to flood quickly. A small drainage basin means that the water will get to the river channel quicker and has a higher chance of flooding. Sometimes drainage basins can be small and the slopes within the area are quite steep. This means that gravity will move the water more quickly towards the river channel and again, this is more likely to cause a flash flood.

Question 82

Explain why deforestation is a human cause of river flooding

Answer 82

If the presence of vegetation helps to slow down the return of water to the river channel, then the removal of this vegetation is going to cause an increase in the surface run-off, and therefore the chances for flooding. Removal of trees also means that the roots that would have helped to hold the soil structure together will not be able to do this anymore. This causes an increase in soil erosion, which can also lead to a rapid increase in flooding.

Question 83

Explain why urban growth is a human cause of river flooding

Answer 83

The world is urbanising at a fast rate, and more and more farmland is being converted into concrete jungle instead. This change of land-use means that less water is held in storage within the drainage basin system. It also means that any water that falls onto buildings and roads gets channelled into drainage pipes very quickly (less infiltration and throughflow), which rapidly returns the excess water to rivers (increased surface run-off). Urban growth can cause a big increase in flooding along a river.

As land is urbanised, the artificial structures will increase discharge due to: roofs, gutters. The impermeable tarmac will stop water storage increasing surface run-off making it more likely to flood.

Question 84

Explain why river management is a human cause of river flooding

Answer 84

Sometimes the actions that local governments take to try to change the shape of a river channel can actually make a flood more likely. For example, the 1953 flood of the River Lynn in Lynmouth was amplified by the decision to try to move the river channel, to allow a hotel to be built in a particular position. Changing the river channel, by making it more narrow or building a bridge at an inappropriate position, can cause the river capacity to be reduced and make flooding more likely.

Question 85

Explain why global warming is a human cause of river flooding

Answer 85

As more water is being melted from ice stores (glaciers and polar ice caps) due to the increase in temperatures, water levels in drainage basins and in the hydrological cycle will increase water levels in rivers.

Question 86

Case Study: Sustainable Management of Rivers

Give the name, date and location of a river flood event within the British Isles

Answer 86

Boscastle
North Cornwall
16th August 2004
River Valency, River Jordan and River Paradise

Question 87

Case Study: Sustainable Management of Rivers
Give the physical causes for a river flood event within the British Isles. (Include seven points and at least two facts and figures)

Answer 87

1. Prolonged rainfall - The whole month of August was wet. Rained 12 of 14 days —> Soil saturation
2. Heavy rainfall - 200mm in 24hrs —> Infiltration restriction
3. Steep valley sides - Rises 300m in only 6km —> Water flows quickly
4. Underlying rock - Slate —> Difficult to percolate into groundwater
5. Thin, I permeable soils - Peat soils —> Couldn’t infiltrate
6. Relatively small drainage basin - 20km*2 —> Water flows quicker to river
7. Little interception - Deforestation

Question 88

Case Study: Sustainable Management of Rivers
Give the human causes for a river flood event within the British Isles. (Include three points and at least two facts and figures)

Answer 88

1. Deforestation - Many trees had been cut down (for farming) —> Rate of interception decreases —> Water travels faster to river.
2. Urbanisation - Many buildings and concrete —> Little infiltration due to impermeable surfaces —> Surface run-off directed at river.
3. Bridges - Bridges built over the river were too small, got blocked by debris (such as trees, etc) —> Small blockage breaks, surge of water down the river.

Question 89

Case Study: Sustainable Management of Rivers
Give the impact(s) on the people for a river flood event within the British Isles. (Include three points and include at least two facts and figures)

Answer 89

1. Death, Injury and homelessness
   No one died
   Injury - Broken thumb
   1,000 people were affected
   7 RAF helicopters airlifted people to safety
   People had to stay in town halls, caravans and friend’s houses while their homes were being repaired
2. Impact on property
   98 properties flooded and damaged
   4 properties were demolished by the force of the water
   4 footbridges were washed away
   115 cars washed away, only 84 were recovered in the harbour, the remainder are unaccounted for
3. Impact on economy
   Cost of rebuilding the town and ensuring a flood like this could never happen again was an estimated £50 million
   Lost business in the aftermath of flood, tourists are afraid of being trapped in the event of a flood. This has affected jobs and incomes in the town.

Question 90

Case Study: Sustainable Management of Rivers
Give the impact(s) on the environment for a river flood event within the British Isles. (Include one point and include at least two facts and figures)

Answer 90

1. Pollution
   31 cars unaccounted for (115-84=31), present in the river and harbours, release oil and petrol.
   Increased amount of water flooded the sewage system so that dirty water floated through the town.

Question 91

Sustainable River Management Strategy

What is a hard engineering strategy?

Answer 91

These require major alternations and changes to the river to try and stop the river from flooding. Generally these involve big building projects, where machinery is used to change the river and new walls or banks are built. These measures are not sustainable in the long term.

Question 92

Sustainable River Management Strategy

What is a soft engineering strategy?

Answer 92

This is where limited alterations take place and flooding is more managed than prevented. These are generally more sustainable, as they use more natural processes and do not damage the environment to the same extent as hard engineering strategies would.

Question 93

List all of the hard engineering strategies. (Give six points)

Note: Use mnemonic

Answer 93

1. Channel enlargement
2. Bridge widening
3. River straightening
4. Levees and embankments (flood walls)
5. Dams/Reservoirs
6. Storage areas/Diversionary Spillways

Conor
Brolly
Really
Likes
Darth
Sidious

Question 94

List all of the soft engineering strategies. (Give three points)

Answer 94

1. Land use zoning
2. Afforestation
3. Washlands

Question 95

Sustainable River Management Strategy

What is Channel Enlargement (Deepening and Widening)?

Answer 95

Flooding can be reduced by increasing the size of the river channel so that it is capable of carrying more water. This means that in times of very heavy rainfall the river is less likely to flood its banks than before the enlargement, as it will be able to transport the water quickly and effectively through the river channel.

Question 96

Sustainable River Management Strategy

What are the advantages and disadvantages of channel enlargement (Deepening and Widening)?

Answer 96

+ Visually similar
+ Protects both sides of the river
+ Protects habitats
- Heavy machinery —> Expensive, and impacts the ecosystem
- Continued maintenance, as bed silts up
- More rapid flow, areas downstream are more likely to flood

Question 97

Sustainable River Management Strategy

What is bridge widening?

Answer 97

Bridges can be widened to stop debris such as trees and boulders from becoming trapped behind them and creating a dam, as this would cause a large wall of water to build up.

Question 98

Sustainable River Management Strategy

What are the advantages and disadvantages of bridge widening?

Answer 98

+ Stops debris from a backlog of water

• Replacement bridge —> Expensive
• Modern bridge, unattractive for tourists

Question 99

Sustainable River Management Strategy

What is river straightening?

Answer 99

Rivers that meander across the river flood plain can be straightened to help increase the velocity of the water. This reduces flooding as the water drains away from the flood plain more quickly. Some parties want rivers straightened for reasons other than reducing flood risk. For example, property developers find it easier to build alongside straight rivers than on bends and farmers prefer more regular field shapes and sizes, as it allows their machinery to reach the corners of fields, so there is little land wastage.

Question 100

Sustainable River Management Strategy

What are the advantages and disadvantages of river straightening?

Answer 100

+ Increased velocity —> Water drains quicker
+ Easier to build property
+ Agricultural field sizes
- Does not always work, river can return to its natural course
- Affects wildlife, fish like to lay eggs in shallowbends (this removes the bends of the river)

Question 101

Sustainable River Management Strategy

What are levees and embankments (flood walls)?

Answer 101

Levees and embankment walls can be built on either side of the river. The walls mean that even if the river floods above the river bank, the water cannot spread over the flood plain and cause damage.

Question 102

Sustainable River Management Strategy

What are the advantages and disadvantages of levees and embankments (flood walls)?

Answer 102

+ Little impact on the river
+ Can be built on either side of the river
+ Even if the river does flood, the water cannot spread and cause damage
- Can be expensive
- Spoils the look of the river
- Prevents water from draining back quickly
- No silt (alluvium) deposited
- Increases speed of water —> If water does break through, it will cause more damage

Question 103

Sustainable River Management Strategy

What is a dam/reservoir?

Answer 103

In many ways dams across the upper course of the river are an obvious way of controlling the amount of water that can travel through the river system. They ensure that the risk of flooding is almost completely reduced and can be used to generate hydro-electricity.

Question 104

Sustainable River Management Strategy

What are the advantages and disadvantages of building a dam/reservoir?

Answer 104

+ Can be used to generate hydro-electric power, which is a cheap and renewable source of energy
+ Risk of flooding almost completely reduced
+ The dam can be used for recreational activities
- Expensive
- Major impact on environment, completely changing the natural landscape and ecosystem

Question 105

Sustainable River Management Strategy

What is a storage area/ Diversionary spillway?

Answer 105

Water can be pumped out of the river and stored in temporary lakes. This reduces the amount of water flow in the river at peak times and the impact of flooding in more sensitive areas. When it is needed it can be pumped back into the river.

Question 106

Sustainable River Management Strategy

What are the advantages and disadvantages of a storage area/ diversionary spillway?

Answer 106

+ Effective
+ Can be pumped back in when needed
+ Water is pumped out of river, which reduces water flow at peak times and reduces impact of flooding in some areas
- Takes up a lot of space

Question 107

Sustainable River Management Strategy

What is land-use zoning?

Answer 107

Land-use zoning involves dividing the flood plain up into areas which experience different degrees of flood risk. Once the flood plain has been divided up into the different zones, an appropriate land-use can be chosen for each zone.

Question 108

Sustainable River Management Strategy

What are the advantages and disadvantages of land-use zoning?

Answer 108

+ Allows the river to flood naturally
+ Minimal disruption and damage to people
+ Effective
+ Relatively cheap and easy to apply to a potential development site
- Cannot realistically be applied to an already developed and built area

Question 109

Sustainable River Management Strategy

What is afforestation?

Answer 109

Planting trees in the upper course of the drainage basin helps to reduce flooding as trees intercept and store the water. This will help stop some of the water entering the river channel and can reduce the risk of flooding.

Question 110

Sustainable River Management Strategy

What are the advantages and disadvantages of afforestation?

Answer 110

+ Good for environment (natural habitats)
+ Timber can be harvested for additional income
- Only reduces the likelihood of flood, doesn’t prevent it
- Takes up space
- Takes long to grow
- Land owners and users must agree

Question 111

Sustainable River Management Strategy

What is a washland/ safe flood zone?

Answer 111

Washlands are areas of land that water can wash into during a flood. They are usually found in the lower course of a river and act a little like storage areas, with the added benefit of helping to increase friction and slow the river down.
Washlands are created by leaving a large area of land next to a river empty to receive any floodwaters.

Question 112

Sustainable River Management Strategy

What are the advantages and disadvantages of a washland/safe flood zone?

Answer 112

+ Increases friction —> Slows down the river
+ Anticipated flooding —> Saves lives
+ May save more expensive areas downstream
- Demolishing existing structures
- Conflict between people and government
- You have to accept flooding to some extent

Question 113

Case Study: Sustainable River Management Strategy

Give the name, location and date of a river flood event outside the British Isles, and include facts and figures.

Answer 113

Mississippi River, USA
River flooded in 1993
Deaths: 43
Evacuees: 50,000
Damage: $12 billion (£8 billion)
Sandbags: 26 million

Question 114

Case Study: Sustainable River Management Strategy

Name the hard engineering strategies used in a river outside of the British Isles, and include facts and figures.

Answer 114

• Levees and embankments (flood walls)
Levees raised to 15 metres and strengthened for a stretch of 3000km

• Straightening river channel
Straightened for over 1750km, cutting off meanders

• Dams
Over 100 built, e.g. Kentucky

• Storage areas/ Diversionary spillways
Example, Bonnet Carré Floodway begins 50km north of New Orleans
Reduces flood risk at New Orleans and Baton Rouge

Question 115

Case Study: Sustainable River Management Strategy

Name the soft engineering strategies used in a river outside of the British Isles, and include facts and figures.

Answer 115

• Afforestation
Trees planted in upper course of river, Tennessee Valley

• Washland/ Safe flood zone
Rock Island, housing demolished

Question 116

How are waves formed?

Answer 116

Waves are created by the transfer of energy as the wind blows across the surface of the sea.

Question 117

What factors affect the size of a wave?

Answer 117

Strength of the wind
Length of time the wind blows
Distance of sea the wave has to cross (Fetch)

Question 118

What is the fetch?

Answer 118

The fetch is the distance that a wave travels in open water.

Question 119

Why does a wave break when reaching the shoreline?

Answer 119

As the waves begin to approach the shore and the water becomes shallower, the amount of friction increases with the seabed and this slows the base of the wave down. However, the friction does not affect the top of the wave. It keeps its energy so the wave starts to build upwards until it eventually rolls over and breaks.

Question 120

What is a constructive wave?

Answer 120

A constructive wave is a wave with a stronger swash than backwash, resulting in deposition which builds up the landscape.

Question 121

What is a destructive wave?

Answer 121

A destructive wave is a wave with a stronger backwash than swash, resulting in erosion of the coastline.

Question 122

What are the properties and characteristics of constructive waves? (Give eight points)

Answer 122

Strong swash, weak backwash
Operate in calm weather
Limited energy
Beach increases in size
Break less frequently (6-9 per minute)
Build up of sediment on beach
Gentle sloping beaches
Low wave height (about one metre high)

Question 123

What are the properties and characteristics of destructive waves? (Give eight points)

Answer 123

Weak swash, strong backwash
Operate in storm conditions
Much energy
Causes erosion, beach decreases in size
Breaks frequently (around 15 per minute)
Removes sediment from the beach
Steep beach angle
High wave height (five or six metres)

Question 124

List the four erosional processes which occur at the coast

Answer 124

1. Corrasion/abrasion
2. Attrition
3. Solution/corrosion
4. Hydraulic action/pressure

Question 125

Definition of coastal corrasion/abrasion

Answer 125

The force of the moving water in the sea throws stones and other eroded particles that it is carrying against the coastline and cliffs, which dislodges more material.

Question 126

Definition of coastal attrition

Answer 126

Attrition takes place when stones and boulders that are being carried by the sea knock against each other and start to wear each other down. This knocks the edges of the stones and results in smaller, rounder stones/pebbles.

Question 127

Definition of coastal solution/corrosion

Answer 127

This is when the salts and acids in the seawater slowly dissolve coastal cliffs (particularly limestone and sandstone).

Question 128

Definition of coastal hydraulic action/pressure

Answer 128

This is when the force of the water pounds into the cliffs and the cracks in the rocks, and dislodges more material.

Question 129

List the four transportation processes which occur at the coast

Answer 129

Traction
Saltation
Suspension
Solution

Question 130

What transportation process carries material along the coast, from one end to the other?

Answer 130

Longshore drift

Question 131

Why and how does longshore drift occur?

Answer 131

Waves usually approach the coast in the same direction as the wind is coming from. As the wave breaks, the swash will carry sediment diagonally up the beach and as the swash dies away, the backwash returns the material straight back down the beach at a right angle to the sea (due to gravity). Eroded sediment is therefore slowly moved along the coastline in a zig-zag course.

Question 132

What are the two different types of coastal landforms?

Answer 132

Erosional landforms

Depositional landforms

Question 133

What is a cliff?

Answer 133

A steep rock face, especially at the edge of the sea, formed by erosion from the ocean and weather.

Question 134

List all of the erosional landforms

Answer 134

Cliffs
Headlands and bays
Wave cut notches and platforms
Cracks, caves, arches, stacks and stumps

Question 135

How are headlands and bays formed?

Answer 135

One of the most spectacular features of the coastline is the formation of bays and headlands. These are formed when outcrops of harder, more resistant rock (such as basalt) and softer, less resistant rock (such as limestone) are found in the same areas. Waves gradually erode the softer rock away, leaving the harder, more resistant rock sticking out into the sea.

Question 136

How are wave cut notches and platforms formed?

Answer 136

When the sea comes up against a solid barrier such as a cliff face, the four different types of erosion go to work trying to break down the rocks. The greatest pressure of erosion is at the base of the cliff, in what is sometimes called the ‘wave attack zone’. The waves start to undercut the foot of the cliff and this starts to create a wave cut notch. The notch continues to widen and undermines the foundation of the cliff face, which causes the cliff to collapse and retreat backwards.
A wave cut platform gets left behind as the cliff retreats further away from the original position. These are generally gently sloping or flat platforms that can be seen as low tide.

Question 137

How are cracks, caves, arches, stacks and stumps formed?

Answer 137

• Crack is opened up by hydraulic action
• An area of weakness in the rock (such as cracks or joints) will start to come under pressure due to the relentless impact of erosion.
• The cracks in the rock will face abrasion and hydraulic action, continually being impacted by the water and will widen any weaknesses in the rock and split the crack into a cave.
• If the cave is being formed in a headland, the cave might be eroded to form an arch.
• If the waves erode the foot of the arch, it may not be able to carry the roof of the arch which will collapse leaving a stack.
• When the stack is undercut and collapses it will leave a stump.

Question 138

List all of the depositional landforms found on the coastline

Answer 138

Beaches

Spits

Question 139

How are beaches (a depositional landform) formed?

Answer 139

Beaches are usually described as being gently sloping areas of land that are found between the high and low water tide marks. They are built up by constructive waves moving deposited material (sand, shingle and pebbles) up the beach. They are generally fully covered by water at high tide and can be fully exposed at low tide.

Question 139

What is a spit?

Answer 139

A spit is a long, narrow ridge of land that is made up from deposited material (sand, shingle and pebbles) along a coastline.

Question 140

How are spits (a depositional landform) formed?

Answer 140

Spits are less common depositional features. A spit is a long, narrow ridge of land that is made up from deposited material (sand and shingle) along a coastline.

There are a few conditions in which spits can form:

1. They are usually found in areas where there is an easily eroded coastline such as Boulder clay.
2. They are formed when prevailing winds help to transport material down the coastline due to longshore drift (provide definition of longshore drift).
3. They are formed where the coastline changes direction (usually where a river estuary meets the sea).
4. The velocity of water from a river and the power of the sea meet at a certain place, causing a loss of energy and deposition.
5. Many spits have a hooked or curved end as it is gradually shaped and re-shaped by the sea.
6. Spits bend because of the direction of waves and wind.
7. Often the area behind the spit will become a salt marsh due to deposition.
8. The spit will grow in size and magnitude over time.
9. The spit must have a constant supply of material, from deposition, or else it will be eroded away.

Question 141

A spit is also known as a …

Answer 141

Spurn head

Question 142

What are the four human activities that occur at the coast?

Answer 142

Residential
Tourism
Transport
Industry

Question 143

Give a definition of residential activities at the coast and understand its conflicting nature in relation to the other activities at the coast

Answer 143

People like living beside the sea and there is a huge demand for houses with access to the sea and sea views. People who already live there want the area to remain attractive, they want employment opportunities and not just investment in tourist facilities. They do not want many more houses making the area overcrowded and creating empty holiday homes.

Residential - People living in towns/cities

Question 144

Give a definition of tourism activities at the coast and understand its conflicting nature in relation to the other activities at the coast

Answer 144

Tourism is a fast growing source of employment and there is an ever-increasing demand for hotels, restaurants, accommodation, entertainment and things for tourists to do whilst on holiday. However, many residents do not want more tourists, as this can also bring increased crime, vandalism, pollution and congestion in small places.

Tourism - Holidays and days out

Question 145

Give a definition of transport activities at the coast and understand its conflicting nature in relation to the other activities at the coast

Answer 145

The more people who live in a place, then the more transportation links are needed for that area. Ships are the most obvious way to transport people and material at the coast but this may require new facilities and infrastructure to be built at a huge cost. Boats can cause pollution which might affect the leisure users of the beaches.

Transport - Roads, railways, harbours/ports

Question 146

Give a definition of industrial activities at the coast and understand its conflicting nature in relation to the other activities at the coast

Answer 146

Some industries use the coast.
Sand can be extracted from beaches and used in building.
Oil refineries and sewage treatment works can be built.
Sea water can be used to cool power stations.
However, most industrial land uses at the coast are unattractive, and tourists and residents are often unhappy about their development.

Industry - Oil, fishing, shipbuilding

Question 147

Past Paper Question 2017 Unit 1 c) ii)

Name the process by which material is left behind on a beach due to a lack of wave energy.

Answer 147

Deposition

Question 148

Name a stretch of coastline

Answer 148

Costa del Sol

Question 149

Give three reasons why a stretch of coastline may need to be protected against erosion

Answer 149

There may be a sandy beach along the coast which needs to be maintained to attract tourists.
There may be hotels along the coast which need to be maintained to attract tourists.
The coastline may have valuable buildings such as an oil terminal which needs to be protected.

Question 150

List all of the engineering strategies used for coastal management

Answer 150

Sea walls
Groynes
Gabions
Beach nourishment

Question 151

What is the aim of sea walls?

Answer 151

To keep the sea out.

Question 152

What is the aim of groynes, gabions and beach nourishment?

Answer 152

To retain cliffs and beaches.

Question 154

Provide a description of sea walls

Answer 154

• A solid wall that separates the land from the sea.
• This is a traditional ‘hard engineering’ method usually constructed of concrete.
• It supports the land while holding back the sea.
• The wave action can beat against the sea wall without eroding the coast.
• It can be designed to absorb and deflect wave energy.

Question 155

Provide an evaluation of sea walls

Answer 155

• Sea walls can be expensive (over £10,000 per metre).
• They need very deep foundations so that they do not erode away.
• They can sometimes be an ugly addition to a beautiful area.
• They can reflect wave energy back into the sea, which can cause erosion further out to sea or somewhere else along the coastline.
• Sometimes sea walls can actually cause the removal of a beach.
• They might need to be replaced every 25-30 years.

Question 156

Provide a description of groynes

Answer 156

• Groynes are wooden, concrete or rock barriers that can be built out into the sea.
• They can trap the sand carried by longshore drift and help to increase the build up of of a deposition beach.
• Usually these are seen as ‘hard engineering’ but it depends on the material being used. Some consider them to be ‘soft’ measures as they enhance the existing beach.

Question 157

Provide an evaluation of groynes

Answer 157

• Groynes can trap sediment that is supposed to be going to another place along the coastline. This means that another area of the coastline is going to be more vulnerable to erosion.
• They are very cost effective.
• They need continual maintenance and replaced regularly.
• Some people see groynes as unattractive and an obstacle for people who like to walk along the beach.

Question 158

Provide a description of gabions

Answer 158

• Gabions are metal cages that are filled with rocks.
• They are usually stacked together to create a wall of rock.
• As the waves crash against the gabion cages, the energy of the water is forced between the spaces in the rocks and the energy is absorbed inside the cage. This stops the cliffs from taking the brunt of the erosion.
• Water then percolates through the rocks and back into the sea.

Question 160

Provide an evaluation of gabions

Answer 160

• Gabions can be a good short term solution. However, they rarely make an effective long term solution, as the cages can split and release the rocks inside, which can be used by the waves to erode the coast.
• They can be relatively cheap to build (as little as £11 per metre).
• The cages are often described as unattractive.
• The cages and rocks can trap debris and pollution, which can rot leaving bad smells and health concerns.
• The cages can provide an ideal habitat for rats.

Question 161

Provide a description of beach nourishment

Answer 161

• This is when sand or pebbles are added to a beach, replenishing it or building it up.
• It is technically a ‘soft engineering’ solution but this depends on where the material is coming from. Soft engineering should not change the structure of the beach through building work. However, the size of the beach is often increased as the beach is made much wider.
• A large, wide beach naturally protects the coastline because the wave energy is absorbed through the sand.

Question 162

Provide an evaluation of beach nourishment

Answer 162

• The sand used must be of similar quality to the existing beach material so that it can integrate with the natural processes occurring there, without causing any adverse effects.
• Sometimes beach nourishment is used alongside groyne schemes.
• Nourishment requires constant maintenance and will need constant recharging of the beach material.
• It can be expensive at between £5,000 and £20,000 per 100m.

Question 163

Case Study: Sustainable Coastal Management Strategy, from within the British Isles.
Give the name of the stretch of coast you are investigating and the three engineering strategies used to protect the coastline.

Answer 163

Newcastle, Co. Down

Groynes
Sea wall
Gabions

Question 164

Case Study: Sustainable Coastal Management Strategy
Evaluate the advantages and disadvantages of the engineering strategies used, and include at least two facts and figures.

Answer 164

Groynes, concrete 1980s
+ Trap sand, protect beach —> Tourists like
- Only lasted 20 years, decayed —> Need replaced (expensive)

Sea Wall, Victorian 1800s
+ Protected hotels/B&Bs
- Washed away 2002, can be eroded and is expensive to replace (£4 million)
- New one 2002, curved reflects but erodes beach, which tourists don’t like, leading to less income

Gabions, Mouth of the Shimna 2006
+ Protects recreational land, important for tourism
+ Breaks wave energy, allowing pedestrians to use footbridge
- Earlier gabions decay, replacing is expensive

Question 165

Unit 1 2017

State the meaning of the term floodplain. [2]

Answer 165

An area of flat land on either side of the river that holds flood water.
An area of flat land either side of the river, made up of alluvium.

Question 166

Unit 1 2017

b)i) Name one land use on this spit. [1]

Answer 166

Visitor centre
Natural reserve
Non-coniferous wood
Track/path/other road
Golf course/club house
Parking/buildings
Sand dunes
Wind pump/wind turbine
Pond

Question 167

Unit 1 2017

d)iii) Explain the impact on both stores and transfers within the drainage basin if trees are cut down. [4]

Answer 167

If trees are to be removed, this will reduce the interception layer. Water will infiltrate into the ground more quickly leading to an increase in surface run off. This will increase the discharge of the river and the possibility of a flood occurring.