Flooding Flashcards

1
Q

What is the water cycle?

A

This is the continuos movement of water between the sea, the land and the air.

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2
Q

What is precipitation?

A

The transfer of water from the air to the land. It may fall as rain, hail, sleet or snow.

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3
Q

Does the amount of water stay the same?

A

The amount of water in the cycle always stays the same!
Some of the water may be stored in the sea, in the air or on land.
Some of the water will be moved or transferred around the cycle.

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4
Q

What is evaporation?

A

The transfer and change of water (from the ground) into vapour

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5
Q

What is transpiration?

A

The transfer as well as the change of water from plants to vapour in the air

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6
Q

What is condensation?

A

Condensaition is when Vapour in the air changes back into a liquid. It forms small droplets that are visible as cloud.

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7
Q

What is surface water?

A

The transfer of water back to the sea over the ground surface.
This is called surface runoff and is easiest to see as rivers.

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8
Q

What is ground water?

A

The movement/transfer of water through the ground back to the sea.

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9
Q

What is the river basin?

A

The river basin is an area of land where rain collects

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10
Q

What is the source?

A

The point at where the river begins

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11
Q

What is the mouth?

A

The mouth is the end of the river where it flows into either a lake or the sea.

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12
Q

What is a channel?

A

Rivers flow in a channel, they have a bank and a bed

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13
Q

What is watershed?

A

The highland boundary/edge of the river basin.

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14
Q

What is a tributary?

A

A small river that flows into the main river

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15
Q

What are six factors that cause flooding?

A

Rock and soil type: impermeable rocks and soils do not allow rain to soak through them. Any
rain that falls will stay near the surface.

Very wet soil: if rain has been falling for some time, the soil may become full of water. Any
further rain is unable to soak into the ground and remains on the surface.

Very dry soil: soil that is baked hard by the sun in dry weather builds up a crust. Rain is
unable to soak through the crust and so remains on the surface.
Steep slopes: rain falling on a steep slope runs quickly downhill. It has little time to soak into
the ground so most stays on the surface.

Cutting down trees (deforestation)
Many of the world’s forests are being cleared to make way for other developments. In some
countries the number of serious floods has more than doubled since large-scale tree
clearing began.

Buildings and roads (urbanisation)
Rain falling on concrete and tarmac is unable to soak into the ground, so stays on the
surface. Gutters and drains then carry the water quickly and directly to the river. Large
towns are most at risk.

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16
Q

What is a river flood?

A

This is when there is too much water for a river to hold so it spreads across the land either side of the channel.

17
Q

What does the Environment agency do in relation to floods?

A

It
monitors rainfall, river levels and sea conditions 24 hours a day in England and Wales

18
Q

What does Floodline do?

A

Floodline issues warnings and gives advice of what to do, before, during and after a flood.

19
Q

What 6 things does the UK do to manage floods?

A

Study rivers and coasts to identify areas at most risk.
ï‚· Recommend building flood defences eg embankments
ï‚· Check rainfall and water levels
ï‚· Issue warnings through radio, TV etc
ï‚· Alert emergency services such as police, fire and army
ï‚· Ensure food and shelter is available for people left homeless

20
Q

What are the causes of Bangladesh floods?

A

Monsoon rainfall. In Bangladesh they get most of their rain during the
month of June- October. They are seeing more than average rain falling
during this period of time.
ï‚· The population is growing in Bangladesh (around 4million a year!) This
means that trees are cut down to provide farmland and housing.
(deforestation)
ï‚· The loss of trees means more rain water is reaching the rivers.
ï‚· Bangladesh has three major rivers that flow through it. The Ganges,
Meghna and Brahmaputra.
ï‚· As the population grows, so too does the need for housing and buildings.
This urbanisation means there are more impermeable surfaces and
more rain water reaches the rivers.
ï‚· 80% of Bangladesh is less than 6m above the sea level. This means it is
very flat and hard for people to find higher ground to escape the floods.
ï‚· The rivers flowing through the country easily overflow their banks,
flooding the floodplain either side of the rivers.

21
Q

How does Bangladesh cope with floods?

A

Main points from the Flood Action Plan:

ï‚· Build dams to control the river flow and hold back the monsoon
rainwater in reservoirs. The stored water could also be used to produce
electricity and irrigate (water) the crops throughout the year.

ï‚· Build embankments and deepen the river channels to stop the river
overflowing. Some of the embankments are 7 m high!

ï‚· 5,000 flood shelters are to be built in areas most at risk. They are cheap
to construct and provide a safe place to almost everyone and would be
well stocked with food.

ï‚· Improve flood warning systems to give people earlier notice of a flood.
They should also instruct people as to what to do before, during and
after the flood.

ï‚· Provide emergency help such as repair embankments, take people who
require medical help, provide food.

ï‚· After care is needed once the flood water goes down. Money and
medicine would also be required and seeds for the people to sow for the
next harvest so they have food next year.

22
Q

What are the issues with the items in the flood plan in Bangladesh?

A

Embankments can trap the rain water, preventing it from returning to
the river making the flooding last longer.
 Embankments make access to the river for fishing very difficult and
many people rely on this for their livelihood.
 Although the flood shelters save lives, they don’t protect the crops and
animals of the people.
 The action plan is very expensive and this country is very poor. Will it
lead to increased debt?!
 Over half a million people will lose their land to the reservoirs being held
behind the dams.
 The dams can lead to deposition of silt on the river bed which can over
time make the risk of flooding increase.

23
Q

List 8 ways to reduce the risk of flooding

A

Forests: Planting trees which will slow down the speed and amount of rain water reaching the rivers.
Embankments: Raising the river banks with earth or concrete to make them deeper.
Dams: Built across the rivers, they trap water and store it in a reservoir. The release of the water can be controlled.
Straight channels: Cutting through the bend in a rivermeans the
flow of the water will speed up and travel more quickly downstream.
Make river channels wider and deepe by dredging the river bed.
Line river channels in high risk areas with concrete to speed up the flow of water
Create overflow channels where floodgates can be opened when river level gets to high and the water goes into the overflow channel.
Allow flooding in a controlled way in areas that will not have an
impact on human life or property. This can also have a benefit of creating new wetland habitats for wildlife.

24
Q

What are the benefits of controlling flooding?

A

Save money in the longer term
Improve water quality
Help support wildlife