Starter
Put these words in the right order to make a sentence describing what a
flood is and when it might happen;
Flooding occurs when…
gets
a river
channel
water than
more
its
hold
can
Flooding occurs when a river gets more
water than its channel can hold
Learning Objectives:
GOOD: You must describe how floods typically occur.
(Level C-A*)
BETTER: You should explain the different human and
physical causes of flooding. (Level C-A*)
BEST: You could describe and explain the effects of
flooding on people and the environment. (Level C-A*)
and
quickly
reaches
the river.
Water
runs over
the
surface
and the
river
floods.
Heavy
rain falls
and
the
ground
fills with
water.
Water
rises
over the
banks
How rivers flood
Learning Objectives:
GOOD: You must describe how floods typically occur.
(Level C-A*)
BETTER: You should explain the different human and
physical causes of flooding. (Level C-A*)
BEST: You could describe and explain the effects of
flooding on people and the environment. (Level C-A*)
a)
Try to write an
explanation of how you
think each of these
things might lead to
flooding
b)
a) Very wet soil
b) Impermeable rock
and soil
c)
c) Hard dry soil
d) Steep slopes
I think ______ might
lead to flooding
because…
d)
Causes of Flooding
Learning Objectives:
GOOD: You must describe how floods typically occur.
(Level C-A*)
BETTER: You should explain the different human and
physical causes of flooding. (Level C-A*)
BEST: You could describe and explain the effects of
flooding on people and the environment. (Level C-A*)
rainfall
rivers
rise
sudden
downhill
soil
volumes
flood
rock
Causes of flooding
ground
soak
water
no
rainstorm
steep
farming
space
grains
seasons
quickly
evaporated
water
cities
plants
soak
straight
rainwater
towns
reduces
run-off
water
spaces
There are many
PHYSICAL causes of
flooding which are to do
with the natural world!
However,
although you’d
probably
imagine that
nature is always
to blame for
flooding, there
are a lot of
things that
humans do
which also lead
to flooding!
PHYSICAL CAUSES OF FLOODING
HUMAN CAUSES OF FLOODING
During heavy thunderstorms the water does not rest
on the ground for long enough to soak in. Huge
amounts of water flow into rivers very quickly and
increase flooding
If there is a town on a floodplain (or in a drainage
basin) gutters, drains and large areas of concrete
will allow water to move into the river at a greater
speed and so make flooding more likely
Long periods of hot dry weather can make soil very
hard. This means it cannot absorb water and
therefore rain runs off it and enters the river more
quickly, overwhelming the river
Ploughing up and down slopes, rather than from side
to side, means water runs down the fields faster,
entering rivers at greater speeds and increasing the
flood risk!
Impermeable rocks do not absorb water. This means
that the water reaches the river more quickly, and
causes flooding
If vegetation and trees have been removed then
there is less interception and water will move to the
river more quickly
Steep valley slopes increase the speed of runoff and
increase the chances of flooding
Dams may burst which will cause a huge increase in
the amount of water in river channels and severe
flooding
If there are large amounts of rain day after day,
the water will saturate the ground and flow more
quickly into a river
Rapid snow melt can lead to lots of water entering
into a river in a short time period; leading to
flooding
Shade in the information in your
boxes to highlight the descriptive
points and the explanations
Learning Objectives:
GOOD: You must describe how floods typically occur.
(Level C-A*)
BETTER: You should explain the different human and
physical causes of flooding. (Level C-A*)
BEST: You could describe and explain the effects of
flooding on people and the environment. (Level C-A*)
How are
people and the
environment
affected?
USA – 2006
- 200,000 people
evacuated in Pennsylvania
because of flooding on the
Susquehanna river
- State of emergency in in
New York, New Jersey
and Pennsylvania
- Roads and bridges
closed
- 9 people killed
How are
people and the
environment
affected?
India – 2008
River Kosi flooded
- 1600 villages affected
- 55 people killed
- Roads linking villages totally
washed away
- People stranded on rooftops or
small areas of dry land
Mexico – 2007
River Grijava flooded;
- 1 million people affected
- 70% of state of
Tabasco under water
- Capital of Tabasco
(Villahermosa) was totally
flooded with only
treetops and roofs visible
- 300,000 trapped in
their homes
- Sandbags used to
protect towns and cities
Kenya – 2007
The River Tana
burst its banks;
Bolivia – 2007
- Many rivers flooded
- 340,000 affected
- 100,000 left homeless
- Roads in Santa Cruz blocked by
mudslides
- 19 people killed as a result of
the Rio Grande flooding
- Town of Garissa,
and houses near the
river, totally under
water
- Bridges and roads
destroyed so aid
could not get to
people (had to be
dropped by plane)
Describe:
This is a very common command word and requires you to give the main characteristics
of something. Questions will often ask you to ‘describe’ a photograph, a pattern on a
graph or a map. You should write an accurate account of what you see. You are trying
to represent in words the picture to the examiner.
Explain:
This is another very common command word. It is asking you to give reasons as to why
something occurs. It is testing your ability to understand how something happens. For
example, park and ride schemes are sustainable because they reduce the amount of
traffic on the roads by encouraging the use of public transport.
Learning Objectives:
GOOD: You must describe how floods typically occur.
(Level C-A*)
BETTER: You should explain the different human and
physical causes of flooding. (Level C-A*)
BEST: You could describe and explain the effects of
flooding on people and the environment. (Level C-A*)