Floods

Question 1

How many people does flooding affect

Answer 1

75 million

Question 2

How many people does flooding kill

Answer 2

20,000

Question 3

Why do flood plains and coasts support high populations

Answer 3

Good farmland and fishing

Question 4

What are the types of floods

Answer 4

River floods.
Coastal floods.
Surface water floods ‘flash’.

Question 5

When do river floods occur

Answer 5

When natural or artificial banks are overtopped. Usually due to high rainfall.

Question 6

Besides rainfall what’s other causes of river floods

Answer 6

Snow melt.
Blockages in river channels.
Straightening of channels encourages them to flow quickly and reduces natural pools and flood pains they can spread into.
Urbanisation.
Removing levees.
Deforestation.
Machinery compacting land.

Question 7

When do coastal floods occur

Answer 7

When the height of the seas surface is raised above the normal level or waves and tides.

Question 8

What causes coastal floods

Answer 8

Storm surges or tsunamis.

Longer term processes like regional land subsidence and global sea level rise also contribute. Thermal expansion

Question 9

Example of regional land subsidence

Answer 9

In Scotland after ice has melted the land rebounds.

Other land like southern England were pushed up because of the weight of ice and is now receding again.

Question 10

When do surface water floods ‘flash floods’ occur

Answer 10

Occur when heavy rainfall overwhelms the drainage capacity of the local area

Question 11

What is the hardest flood to predict

Answer 11

Flash flood

Question 12

What are the immediate hazards of a flood

Answer 12

Drowning or being hit by floating objects.
Electrocution.
Hypothermia.
Mudflows and debris flows.

Question 13

What classifies a debris flow

Answer 13

47% debris in water

Question 14

Why shouldn’t you walk or drive through flood water

Answer 14

Because 15cm of fast flowing water can knock you over.

60cm can float your car.

Question 15

What are the long term hazards of flooding

Answer 15

Contamination of freshwater.
Epidemics of waterborne diseases.
Agricultural losses -> food shortages.
Damage to homes, schools and workplaces -> economic loss.

Question 16

How are food shortages after a flood mitigated

Answer 16

By global distribution of food and humanitarian aid but in the past it could cause famines

Question 17

Steps to reduce vulnerability

Answer 17

Land use planning.
Flood reduction measures.
Flood diversion/defence measures.
Flood proofing buildings and contents.
Forecasting and warning.
Education.

Question 18

How does landuse planning help

Answer 18

Mapping a flood hazard shows flood frequency, water depth and flow velocity.
Implement land use policies like exclusion zones and building regulations.

Question 19

Examples of flood reduction measures

Answer 19

Reforestation to reduce sediment loss and increase uptake of water by plant roots.
Creation/protection of water retaining ecosystems like wetlands.
Permeable surfaces in urban areas.

Question 20

Examples of flood diversion/defence measures

Answer 20

Construct levees (artificial embankments and dykes)
Enlarge channels or create overspill channels.
Construct storage reservoirs. (Favoured)

Question 21

Example of enlarging a channel

Answer 21

Dredge sediment

Question 22

How to flood proof buildings

Answer 22

Elevate living space on stilts or mounds.
Sealable doors, windows and cellars.
Store food in watertight containers high up.
Electrical connections at head height.

Question 23

Example of flood proofing

Answer 23

After hurricane Hugo’s 6m flood surged caused serious damage in 1989 the rebuilt houses in S Carolina are elevated

Question 24

Down side of elevating houses

Answer 24

Accessibility issues.
Foundations and soft storey have to be really strong.
False sense of security so people could end up stranded.
Expensive.

Question 25

Example of an agency that does forecasting and warnings

Answer 25

Environmental Agency in England and Wales

Question 26

How many properties are at risk in England and Wales

Answer 26

1 in 6

Question 27

What do the environmental agency do

Answer 27

Model flood behaviour and drainage basin characteristics. Monitor storms and predict precipitation and flood using satellite and radar data. Issue flood alerts and warnings.

Question 28

Why can you be indirectly affected by flooding

Answer 28

Through power cuts if the infrastructure is poorly designed around town

Question 29

How do the environmental agency issue flood alters and warnings

Answer 29

Via website, local radio, email/phone/text, and in some areas sirens and loud hailers

Question 30

What are the stages of the flood altering system

Answer 30

Flood Alert Flood warning Severe flood warning

Question 31

What does the flood altert mean

Answer 31

Means that flooding is possible and that you need to be prepared

Question 32

What does the flooding warning mean

Answer 32

Means flooding is expected and you should take immediate action

Question 33

What does severe flood warning mean

Answer 33

Means that there is severe flooding and danger to life

Question 34

How should you respond to a flood alert

Answer 34

Tune in to local radio on battery or wind up radio. Move items to safety. Assemble emergency kit. If time, fit flood protection products.

Question 35

What is in an emergency kit

Answer 35

Medication, water, spare clothes, torch.

Question 36

Examples of flood protection products

Answer 36

Flood boards Airbrick covers Sandbags Toilet bungs

Question 37

What should you do if a flood warning is issued

Answer 37

Same as flood alert plus switch off electricity, gas and water supplies. Be prepared to evacuate to higher ground, call 999 if in danger

Question 38

Case study for flooding

Answer 38

Bangladesh

Question 39

What is Bangladesh classed as

Answer 39

The worlds most flood prone country

Question 40

What is the size and population of Bangladesh

Answer 40

Similar size to England and Wales but a population of 160 million

Question 41

Why is flooding a big risk in Bangladesh

Answer 41

Most people live on low lyingflood plains and rely on agriculture for their livelihood. Largest river delta in the world. River erosion is a problem. Rivers swelled by snow melt in spring and monsoons in summer.

Question 42

What is the river delta in Bangladesh

Answer 42

Ganges draining an area 11x Bangladesh before it goes into Bay of Bengal

Question 43

Where does the snow melt in spring in Bangladesh comes from

Answer 43

The Himalayas

Question 44

Normally how much of Bangladesh is inundated during monsoon season

Answer 44

20-25%

Question 45

How much of Bangladesh is inundated during monsoon season during extreme events (monsoon and snow melt)

Answer 45

Up to 75% can flood

Question 46

What percentage of the population in Bangladesh life within 1m of sea level (not from the sea)

Answer 46

17%

Question 47

Why is there a threat of permanent flooding in Bangladesh

Answer 47

Sea level rise

Question 48

How many cyclones per year are in the Bay of Bengal (don’t all affect Bangladesh)

Answer 48

16

Question 49

What is a big problem in some areas of Bangladesh

Answer 49

Saline intrusion

Question 50

Why is there increasing hazard levels in Bangladesh due to climate change

Answer 50

It is subsiding and sea levels are rising. Himilayan glaciers are melting and receding. Long term reducing in ice cover.

Question 51

What is the organisation to reduce vulnerability in Bangladesh

Answer 51

Cyclone Preparedness Programme (CPP). Organised by the Bangladesh government and red crescent society

Question 52

What has Bangladesh done to reduce vulnerability

Answer 52

Thousands of cyclone shelters constructed and a large network of volunteers trained to disseminate warnings and assist with evacuation (no high ground so elevated). Education and training.

Question 53

What does the N. Indian Ocean now have

Answer 53

Storm surge modelling and forecasting programme (and IOTWS) after 2004 Boxing Day tsunami

Question 54

What is the comparison between major cyclones in Bangladesh

Answer 54

In 1970 Bhola cyclone nobody knew was coming so Cyclone preparedness programme put in place. In 1991 there was some success but not enough so in 2007 the Sidr cyclone had an increased focus on training volunteers to get people to sheltered and deaths dropped dramatically with the same amount of people evacuated as in 1991.