Term 3 - Water on the land Flashcards Preview

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Flashcards in Term 3 - Water on the land Deck (83):
1

CASE STUDY
What were the causes of the Bangladesh floods?

Bangladesh is a massive floodplain.
Most densely populated country in the world.
Roads increase runoff.
Glaciers melting means more water.

2

CASE STUDY
What were the impacts of the Bangladesh floods?

Destruction of crops and houses.
Poverty.
No flood protection.
More prone to flooding.
No resources for the poor.
People constantly moving and looking for homes and work.
People migrate to Dhaka for work.
People live on edge of river which makes flood worse.
Land price has gone up because of protection.

3

CASE STUDY
How have Bangladesh managed the floods?

Distributing resources and kits.
Building underground drains.
Building cluster villages which are above flood level and include school and other shared resources.
Giving people basic training in fish to sell and earn more income.
Land that wasn't being used before is now being used to grow crops to be sold and eaten.
Animals.

4

What is evaporation?

Where water droplets change into water vapour.

5

What is transpiration?

Water vapour is released through the stomata in the leaves.

Stomata - small opening in plants which allow water or gas to pass.

6

What is condensation?

Cooling vapour turns into liquid.

7

What is precipitation?

Water that falls on the earths surface e.g. rain, snow, hail.

8

What is ground water?

Water flows horizontally through the rock into the river.

9

What is surface runoff?

Water flows horizontally over the land into the river.

10

What is through-flow?

Water flows horizontally through the soil into the river.

11

What is infiltration?

Water seeps into the ground.

12

What is the hydrological cycle?

The continuous movement of water between the land, the sea and the air.

13

What is the drainage basin?

The area of land drained by a river.

14

What is a tributary?

A small river which flows into a larger river.

15

What is a confluence?

Where two rivers meet.

16

Where is the mouth of a river?

Where it flows into the sea, or sometimes a lake.

17

What is the watershed?

The boundary dividing one drainage basis from another - a ridge of high land.

18

What is the source of a river?

The upload area where the river begins.

19

What is the flood plain?

Land that gets flooded when the river overflows.

20

What is the catchment?

The area from which water drains into a particular drainage basis.

21

What is hydraulic action?

The force of the river against the beds and banks. The pressure weakens and wears away rocks.

22

What is attrition?

Rocks being carried by the river smash together and break into smaller, smoother and rounder particles.

23

What is corrosion/solution?

Soluble particles are dissolved into the river.

24

What is abrasion?

Rocks carried along by the river wear down the river bed and banks.

25

What are the land forms found in the upper course of a river?

The source.
Large angular rocks.
Mountainous/hilly.
V-shaped valleys.
Steep gradient.
Waterfalls and rapids.
Slow flow with some fast turbulent flows.
Lots of tributaries.

26

What are the land forms found in the middle course of a river?

Lots of tributaries.
Flatter valley.
Becomes deeper and wider.
Small channels and streams.
Medium sized pebbles.

27

What are the land forms found in the lower course of a river?

The mouth.
Widest and deepest.
Deep water.
Pebbles.
Meanders, estuary, delta.
Flatter land.
Floodplains.
Fine sediment.
Faster flow.

28

What are erosional land forms?

Waterfalls in the upper course.

29

What are erosional and depositional land forms?

Meanders and oxbow lakes in the middle course.

30

What are depositional land forms?

Levees and floodplains in the lower course.

31

What is sinuosity?

How bendy or curvy.

32

What is thalweg?

Fastest flow.

33

What is energy (up arrow)?

Helical flow.

34

What is helical flow?

Corkscrew like flow of water.

35

What is sideways erosion?

Lateral erosion.

36

What is peak rainfall?

When rainfall is at its highest.

37

What is peak discharge?

The highest amount of water in the river.

38

What is discharge?

The amount of water in the river.

39

What are flood hydrographs?

Shows how a river's discharge changes over time in response to a rainfall event.

40

What are permeable rocks?

Allows liquids or gases to pass through it.

Sandstone
Chalk

41

What are impermeable rocks?

Not allowing liquids or gases to pass through it.

Slate
Marble
Granite

42

What does a hydrograph show?

- Discharge is the amount of water passing a given point at a given time.
- The river's discharge increases until it reaches its peak. Surface runoff is the first water to reach the river and then through flow.
- The falling limb shows the speed at which the river returns to its normal (base) flow.
- Lag time is the rime between the maximum rainfall and the peak discharge.

43

What affects the shape of a hydrograph?

- Land use - expanding towns and cities create more impermeable surfaces so increases surface runoff and reduces lag time. Drains and sewers also increase discharge.
- Man-made objects.
- Relief.
- Geology and soil - how permeable a rock type is affects how much surface runoff will occur. Impermeable and non-porous rocks do not allow water to infiltrate so increases surface runoff.

44

What affects the shape of a hydrograph?

- Gradient of the valley sides - relief affects rate of water runoff. Steep slopes encourages fast surface runoff and a short lag time. Gentler slopes allow infiltration to occur and reduces runoff.
- Temperature - affects the loss of water from the drainage basin and therefore the level of discharge. Higher temps lead to higher outputs of evaporation and transpiration.
- Drainage density - permeable and porous rocks will allow water to infiltrate into the ground.

45

What affects the shape of a hydrograph?

- Vegetation coverage - trees intercept rainfall with their leaf canopies. If removed less water intercept and soaked up via roots. Surface runoff and through flow increase, increasing river discharge.
- Type and amount of precipitation - the amount and type of rainfall is important in influencing river discharge. High amounts of rain saturate (fill up) the soil and increase surface runoff. This reduces the lag time.

46

CASE STUDY
What were the causes of the Boscastle floods?

- Local area saturated by weeks of rainfall.
- Confluence of 3 rivers increase discharge.
- Steep V-shaped valleys increased runoff.
- 15mm of rain fell in 15 mins.
- Impermeable underlying rock reduced infiltration.
- Car parks increased surface runoff.

47

CASE STUDY
What were the effects of the Boscastle floods?

- 3m wall of water destroyed infrastructure (homes, offices, bridges) sweeping cars out to sea.
- Silt and debris left after flood waters subsided.
- Homes devalued and insurance up.
- £15m in damages and claims.
- No deaths.
- Tourism reduced. Serious cost for small community with seasonal employment problem, over-reliant on summer tourism.
- Visitor centre collapsed.

48

CASE STUDY
What was the short term/immediate response to the Boscastle floods?

- Environment agency issues flood warnings.
- Falmouth Coast Guard mobilised.
- Lifeboats and motorised dinghies rescue people from houses and check cars out at sea.
- Temporary accommodation set up.
- Fire brigades and police on scene within an hour.
- Rapid evacuation.
- RAF helicopter saved 150 people.

49

What was the long term response to the Boscastle floods?

- Boscastle residents banned from returning to look at their homes for first ten days while structural engineers inspected properties.
- Telephone, water, electricity and gas reinstalled within 6 months.
- Insurance and compensation provided for business and homeowners. 'Disruption to trading' claims were £15m.
- Within 6 months residents were home, following extensive clear up and removal of silt and debris.

50

Describe formation of a gorge.

- River meets band of softer, less resistant rock.
- Underlying softer rock eroded away more quickly.
- More resistant rock left unsupported and overhangs.
- Eventually more resistant rock collapses into riverbed.
- The rock causes abrasion of riverbed.
- Hydraulic action also helps to create deep plunge pool.
- Process is repeated and waterfalls retreat upstream.
- Steep sided river valley is created called a gorge.

51

Describe formation of a meander.

- Slowest flow on inner bend and shallowest point.
- Faster flow on outer bend and deepest point. Helical flow takes place.
- Material deposited at inner bank forming point bar. A slip off slope forms.
- Outer bend gets eroded. River cliff begins to form.
- Inner bank continues to grow.
- Over time the outer bank gets worn away.

52

What is a point bar?

Low, curved ridge of sediment along inner bank.

53

Describe formation of an oxbow.

- Continued erosion and deposition may lead to the formation of an oxbow lake.
- Neck of meander narrows due to continuous erosion on outer bend.
- Eventually the neck is broken through.
- Leaving a straight channel behind.
- Over time an oxbow lake dries up, a meander scar will form.

54

Describe formation of levees.

When the river floods it spreads over the surrounding land.

The sediment in a river floods over the surrounding land.

55

CASE STUDY
What were the causes of the Pakistan floods?

- Heavy monsoon rain for months so saturated ground.
- High surface runoff from Himalaya mountains, due to steep relief and impermeable rock.
- River Indus broke its banks on 9 August flooding large areas of northern Pakistan.

56

CASE STUDY
What were the social effects of the Pakistan floods?

- Farmland and crops ruined by silt deposits.
- Heavy reliance on international aid (Red Cross, Oxfam).
- Over 1,600 died. 14 million impacted.
- UN Ambassador Angelina Jolie helped raise publicity.
- Taliban took advantage of slow response to supply aid and win over communities in the north.
- Response was slow and uncoordinated. Death toll and suffering rose, and people living out in the open contracted more diseases.

57

CASE STUDY
What were the social effects of the Pakistan floods?

- Cholera is an infection of the intestine cause by eating food or drinking water contaminated with the bacterium Vibrio cholera. Violent diarrhea and vomitting quickly lead to sever dehydration and death if treatment is not given.
- "People are swimming in flood water, water that's pick up all the dirt and germs that were in the ground and in places where sanitation standards were lacking. People are bathing in contaminated water" said Thomas Batardy of Medicines Sans Frontieres.

58

CASE STUDY
What were the economic effects of the Pakistan floods?

- Farmland and crops ruined by silt deposits.
- Heavy reliance on international aid.
- Sukkur Barrage (a small dam) was breached - this intensified the flooding to the south.
- International response was slow, as world had just given to Haiti disaster (donor fatigue).
- Response was slow and uncoordinated. Death toll and suffering rose, and people living out int he open contracted more diseases.

59

CASE STUDY
What were the environmental effects of the Pakistan floods?

- Farmland and crops ruined by silt deposits.
- The Swat Valley was most severely affected area.
- Heavy monsoon rain for months so saturated ground.
- "People are swimming in flood water, water that's pick up all the dirt and germs that were in the ground and in places where sanitation standards were lacking. People are bathing in contaminated water" said Thomas Batardy of Medicines Sans Frontieres.

60

CASE STUDY
What were the political effects of the Pakistan floods?

- Heavy reliance on international aid.
- Taliban took advantage of slow response to supply aid and win over communities in the north.

61

CASE STUDY
What were the responses and how were the Pakistan floods managed?

- Heavy reliance on international aid.
- Swat Valley inaccessible by helicopters, aid agencies used donkeys. Took longer to reach communities.
- Taliban took advantage of slow response to supply aid and win over communities in the north.
- Cholera is an infection of the intestine cause by eating food or drinking water contaminated with the bacterium Vibrio cholera. Violent diarrhea and vomiting quickly lead to sever dehydration and death if treatment is not given.
- International response was slow, as world had just given to Haiti disaster (donor fatigue).

62

What type of engineering is there?

soft and hard

63

What are some hard engineering types?

Dams (and reservoirs)
Straightening

64

What are some soft engineering types?

Afforestation
Floodplain zoning
Warning and preprations

65

CASE STUDY

What is the general information for the Three Gorges Dam?

On River Yangtze, China
Constructing a dam in the upper part of the river allows people to control the amount of discharge in the river further down its course.
A dam may cause sediment to get caught in the upper sections of the river.
Cost - $25 billion - cost believed to be higher. Work began in 1993 due for completion in 2009

66

CASE STUDY

What are the advantages of the Three Gorges Dam?

HEP (hydro electric power) produced for a growing Chinese population.
Less flooding on Yangtze - 1/100 to 1/1000 flood likelihood.

67

CASE STUDY

What are the disadvantages of the Three Gorges Dam?

1.4 million relocated
Many settlements lost - 13 cities, 140 towns and over 1,300 villages submerged.
No compensation
Dam prevents deposition of alluvium on farmland - less fertile land
Most populated reservoir on earth - 265 billion gallons of raw poop (sewage) pumped in every year

68

CASE STUDY

What is the general information for the Mississippi River?

It is in the USA
Straightening meanders is a small scale approach to managing rivers. Reducing the river's sinuosity increases the velocity (speed) of the river discharge. Changing the river channel can allow a larger amount of water to flow quickly through the river.

69

CASE STUDY

What are the advantages of the Mississippi River?

A linear river flows more quickly - a sinuous river flows more slowly.
River straightened means water moves away from the city more quickly.

70

CASE STUDY

What are the disadvantages of the Mississippi River?

Lead to flooding downstream.

71

CASE STUDY

What is general information for the Yellow River?

It is in China.
This involves the planting of trees and vegetation in the drainage basin to help lower river discharge and flooding. Remember, vegetation intercepts precipitation reducing runoff and increasing the lag time (time between peak rainfall and peak discharge). Trees like willow are used a lot; they intercept and suck up a lot of water.

72

CASE STUDY

What are the advantages of the Yellow River?

Planting of trees to increase interception.
Increases lag time (takes longer for precipitation to reach the river).
20% increase in trees in 2 years.
Lessens flood impacts.
Provides habitat.
Provides employment.

73

CASE STUDY

What are the disadvantages of the Yellow River?

Only lessens the impact of flooding.
Does not stop flooding.
Insurance of properties will still be high.

74

CASE STUDY

What is the general information of the Rhine River?

It is in Germany.
Some parts of the river are allowed to flood naturally in rural areas to reduce the risk to urban areas. Governments and Local Authorities can control where homes are built. The idea being not to let homes be built on high risk areas of the flood plain. Flood plain zoning is a sustainable method of managing flooding, it seeks to be socially, economically and environmentally beneficial.

75

CASE STUDY

What are the advantages of the Rhine River?

Works with the environment.

76

CASE STUDY

What are the disadvantages of the Rhine River?

Land is lost.

77

CASE STUDY

What is the general information for warnings and preparations?

Environmental Agency, UK
As in the case of Boscastle the EA work closely with the Met Office to give out weather warnings. Yellow, amber and red (take action) and warnings. People can be informed to put out sandbags, move furniture and belongings upstairs or evacuate properties. Emergency services informed by the EA.

78

What are the rising water demand reasons?

- washing machine
- shower
- cooking
- drinking
- pooping
- outside use
- dishwasher
- population density

79

What does area of deficit mean?

The dry part of the country - in the UK it is the South East.

80

What does area of surplus mean?

Wetter part of the country - in the UK it is the South West.

81

What is water transfer?

Areas of deficit do not have enough water and areas of surplus have more than enough water so the big tubes/pipes transfer the water from the surplus part of the country to the deficit part to keep up with water demand.

82

EXAM QUESTION

Describe how the shape or a river valley changes downstream (4 marks).

In the upper course, the source is located and vertical erosion happens and creates a V shaped valley. The upper course has the slowest flow with some fast turbulent flows. In the middle course, lateral erosion happens and creates a U shaped valley. The middle course has a faster flow. In the lower course, it is the deepest and widest and has the fastest flow.

83

EXAM QUESTION

Explain the formation of a gorge (4 marks).

Gorges occur in the upper course. The harder rock lies on top whereas the softer rock lies underneath. The softer rock gets undercut and forms a plunge pool, creating a gorge.