Transcript Drought, Deserts and Desertification

Why was this cow stuck up a tree?
CASE STUDY:
TOO LITTLE
WATER!
Drought,
Deserts
and
Desertification
Write
this title
What do
these terms
mean?
THE SAHEL, AFRICA
Some key terms and definitions. (Match and copy)
• Drought -
the destruction of soils
and vegetation in arid
(dry) regions
• Desert -
an extended period of
drier weather than is
usual (in the Sahel this
can last for more than
10 years)
• Desertification -
A dry area, hot or cold,
where total annual
precipitation is less than
250 mm. Usually treeless
Identify which picture
shows…
1. DESERT,
2. DROUGHT,
3. DESERTIFICATION
Examples of case studies from Papers 1 and 2 that you
should be able to answer by the end of this topic.
2003: A place where a serious flood or drought has affected people
and the environment.
(i) Name a place where you have studied a serious flood or drought.
(ii) Describe how the flood or drought affected people and the
environment.
(iii) Explain what people could do or have done to prevent the flood or
Can you work
drought affecting them in the future.
which
2008 and 1999: A type of climate and its effects on out
people
andunits
the
these case
environment.
(i) Name and locate a type of climate you have studied.studies are
from?
(ii) Describe the main features of the climate type.
(iii) Explain how it affects people and the environment.
1999: A water shortage and its effects on people and places.
(i) Name a place which has been affected by a water shortage.
(ii) Describe how the water shortage affected people and places.
(iii) Explain what caused the water shortage.
Where is the Sahel?
As an introduction,
watch this short
film. You will be
asked some
questions about it
at the end
TASKS: 1. Using an atlas, describe the
location of the Sahel. Refer to continent,
latitude, desert, etc. (if this was an exam
question, it would be worth 4 marks)
2. On your map of Africa, shade the
Sahel region (add a key), label the
countries that are within the Sahel and
stick it in your book.
This image does suggest
that the Sahel is an area
that is hard to define in
terms of area. However, it
is an area that is spreading.
What is the climate like in the Sahel region and
how can it be explained?
The climate of the Sahel
Climate statistics for Kano, Nigeria
J
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A
M
J
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S
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Av
Copy the title at
the top of this
slide and then
complete the
Some reasons for the climate of the Sahel
tasks
the
For seven months of the year the Sahel is covered by hot, dry air moving southwards from
the on
Sahara
Desert
(the Harmattan air mass). Only from may to September does warm, moist air from the Atlantic (the
worksheet
monsoon air mass) push northwards across the Sahel. Where these two air masses meet is known as the
Temperature
Mean Value
°C
21.
2
Precipitation
Mean Monthly Value
mm
0.0
24.
4
28.
7
31.
3
30.
9
28.
2
26.
2
25.
5
26.
6
27.
3
24.
6
21.
6
26.
38
0.3
1.6
11.
6
49.
6
118
.2
173
.8
228
.0
103
.1
10.
2
0.0
0.0
58.
03
inter-tropical convergence zone and it is here that clouds form and may become heavy enough for rain. The
problem is that in some years the moist air does not push so far north and does not stay so long. This is
something that is not understood fully. These are ‘dry’ years and can last for many years (drought).
TASKS:
1.Describe the climate of Kano during the year.
2.Now try to explain the climate of the Sahel. To do this, use these questions to help you...
(a)Why is it so hot? (think of another reason not covered above as well)
(b)Why is the rainfall seasonal?
(c)Why is the rainfall unreliable?
TOO LITTLE WATER: The Sahel Region of Africa
While watching the video, complete a copy of this grid for your course notes:
CAUSES OF DROUGHT
IMPACTS OF DROUGHT
SOLUTIONS TO DROUGHT

HUMAN CAUSES


SHORT-TERM SOLUTIONS

NATURAL CAUSES


LONG-TERM SOLUTIONS

Colour-code the causes
according to whether they are
HUMAN or NATURAL.
Think of some categories you
could use to separate the
impacts, add them to the key
and colour-code them.
Colour-code these according to
whether they are SHORT-TERM or
LONG-TERM solutions.
Why does the Sahel suffer from
desertification?
Increase in population
Loose top soil blown
away by wind
(Soil Erosion)
Loose top soil blown
away by wind
(Soil Erosion)
Increase in cattle
Leaves no longer
protect soil from
weather
Roots may be eaten as
well as grass
Less vegetation means
less protection from
weather
Roots no longer hold
soil together
Grassland grazed more
intensively
Deforestation for fire
wood
Write the title above.
Cut out and arrange your
cards into two collumns of
flow diagrams to show
how desertification takes
place. Stick them in your
book.
E.g.
Increase in cattle
Increase in
population
Why does the Sahel suffer from desertification?
DESERTIFICATION
Increase in cattle
Increase in population
Deforestation for fire wood
Grassland grazed more intensively
Roots no longer hold soil together
Roots may be eaten as well as grass
Leaves no longer protect soil from weather
Less vegetation means less protection
from weather
Loose top soil blown away by wind
Loose top soil blown away by wind
(Soil Erosion)
(Soil Erosion)
= DESERTIFICATION
=
How can desertification
be prevented?
Are there any solutions
to the problem?
Irrigation
Barriers to
wind erosion
Wind energy
Working together
Education
Crop rotation and
careful selection
Solar energy
Reforestation
Stopping soil erosion
Solutions to DESERTIFICATION
How you present these
answers is your decision
BUT you must make sure
that they are easy to
revise from and not too
wordy
TASK
Use your notes
from the video,
p.44-45 of the
textbook
‘weather, Climate
and Ecosystems’
and the A4
information sheets
to answer these
key questions.
What can native people do?
What can the African governments do?
What can other nations and NGO’s do?
NGO = a non-government organisation, e.g. Oxfam
Examples of case studies from Papers 1 and 2 that you
should be able to answer by the end of this topic.
2003: A place where a serious flood or drought has affected people
and the environment.
(i) Name a place where you have studied a serious flood or drought.
(ii) Describe how the flood or drought affected people and the
environment.
(iii) Explain what people could do or have done to prevent the flood or
Are you now
drought affecting them in the future.
to answer
2008 and 1999: A type of climate and its effects on able
people
and the
these case
environment.
(i) Name and locate a type of climate you have studied. studies
(ii) Describe the main features of the climate type.
(iii) Explain how it affects people and the environment.
1999: A water shortage and its effects on people and places.
(i) Name a place which has been affected by a water shortage.
(ii) Describe how the water shortage affected people and places.
(iii) Explain what caused the water shortage.
Solutions to the problem of desertification?
Restore and fertilize the land
A simple and cheap way to fertilize the land is to prepare compost, that will become humus and will
regenerate the soil with organic matter.
Combat the effects of the wind
By constructing barriers and stabilising sand dunes
with local plant species.
Reforestation
Trees play several roles: they help fix the soil, act as wind breakers, enhance soil fertility, and help
absorb water during heavy rainfall.
Because the burning of land and forests increases dangerous greenhouse gases, afforestation –
planting new trees - can help reduce the negative impacts of resulting climate change.
Develop sustainable agricultural practices
Drylands are home to a large variety of species, that can also become important commercial
products: for example, they provide 1/3 of the plant-derived drugs in the United States. Agriculture
biodiversity must be preserved. Land overexploitation shall be stopped by leaving the soil ‘breathe’
during a certain-time period, with no cultivation, nor livestock grazing.
Traditional lifestyles
Traditional lifestyles as practiced in many arid zones offer examples of harmonious living with the
environment. In the past, nomadism was particularly adapted to drylands conditions; moving from
one waterhole to another, never staying on the same land, pastoral peoples didn’t exert much
pressure on the environment. However, changing lifestyles and population growth are putting
increasing pressure on scarce resources and vulnerable environments. The Silk Road in Asia and the
Trans-Saharan route in Africa are good examples of the vigorous economic and cultural exchanges
developed by nomadic societies.
Solutions to the problem of desertification?
•
•
•
Fertilize the land to restore it
To combat desertification it is necessary to restore and fertilize the land.
Nutritive elements such as nitrogen, phosphorus, calcium, magnesium etc. in the soil are necessary for plants to grow.
When the soil has lost all its nutritive elements or a part of its constituents (removed by wind or water) it is said to be
degraded or exhausted and its productivity diminishes as a consequence. It can also accumulate such toxic elements as salt
that need to be eliminated.
As these elements become exhausted through intensive agriculture it becomes necesssary to re-establish soil fertility either by
using synthetic fertilizers or by preparing much cheaper compost. It is principally prepared from plant waste: manure,
agricultural trimmings (straw), and biological household waste. Water hyacinths, though harmful in rivers, can be transformed
into fertile matter that supplies nutritive elements to the soil as compost.
After several weeks in a pit, and with the heat and humidity, humus is produced. It can then be spread among the crops and
used to prepare the soil before seedlings are planted. The soil regenerated with organic matter in this way will produce more
fruitful harvests. The restructuring of the soil is a very effective and particularly sustainable way to maintain soil fertility.
The presence of livestock could also be exploited to enrich the soil. By consuming crop leftovers the animals return nutritive
elements to the soil that enriches it with nitrogenous matter in the form of dung. Dung also restores the capacity of soil to
produce a more plentiful harvest. The herd also provides meat and milk. In this way, farmers and cattle rearers can help each
other.
Combating the effects of wind
Some simple mechanical means to alleviate the effects of wind that prevent the displacement of sand and dust, include:
• the construction of fences or barriers from local plant species: woven palms, planted hedges (rows of maize or
millet that protect beans and onions) or metal sheeting around villages and crops.
• planting vegetation whose roots protect and fix the soil.
• prohibiting livestock from grazing to protect the areas of plantation.
Reforestation
This requires the creation of nurseries to nurture young plants among local species selected for their rapid growth and adaptation to
the harsh climate. Reforestation is a long-term action since tree growth is slow.
Trees play several roles:
• they fix soil elements and prevent their loss by water and wind.
• they act as obstacles to the wind (wind-breaker) to protect crops (trees should be pruned to be more effective).
• they enhance soil fertility: many trees produce nitrogen (due to the presence of bacteria in roots) that fertilizes and increases soil
productivity.
• they facilitate water penetration into the soil during the rains and contributes to maintaining humidity for a long time.
• they provide shade for animals and people.
•they supply nutritive elements: fruit trees diversify food sources, trees provide fodder for livestock (during the dry season).
•
•
•
Substituting wood
A large number of populations use wood as their major source of energy, which contributes further to desertification
(through deforestation) and increases the greenhouse effect (by releasing carbon dioxide).
The non-sustainable use of forest resources (firewood) as a source of energy is a factor leading to desertification.
Therefore, identifying and employing alternative renewable energy sources is important in the fight against desertification.
Non-polluting and renewable energies can replace wood at limited or no cost (the energy source is free) and they can
easily be used by families in villages.
e.g. Solar energy:
Bright sunny conditions, characteristic of arid regions, can satisfy energy needs in these areas.
Solar energy can be used in multiple ways:
parabolic mirrors help cook food, produce water vapour and run electric water turbines.
panels transform sunrays into electricity. The electric current is stored in batteries and can be used day or night. Despite
the present high cost, it is hoped that this option will become more affordable in the future.
the evaporation power of the sun can produce distilled water, free of salt and germs, by using a solar distiller.
e.g. Wind
The force of the wind can drive wind propellers that produce electricity. The wind energy can generate a pump to extract
water from wells, fill watering holes or irrigation basins or activate mills to transform grain into flour.
This type of energy will facilitate land irrigation and the supply of water to the livestock.
e.g. Biogas
This is a gaseous mix produced in a fermentation tank that comes from the decomposition of dung and plant waste. The
leftovers from the fermentation can be used as natural fertilizer (compost). The high temperatures in the drylands are
beneficial to the creation of biogas. Its advantages: it is uncostly and can be used for lighting, cooking or to drive motors
(generators, tractors and cars). Biogas can also be produced in small installations. This technique can most effectively be
developed in regions where agriculture and cattle rearing coexist.
Developing education and training
It is important that every individual has access to information and understands the action proposals communicated by the
media and literature. Reading and writing skills provide people the opportunity to become better informed and help them
understand and organize projects that combat desertification. Education therefore enables them to share knowledge and
better manage the available resources.
THE FOLLOWING SLIDES
ARE FROM PREVIOUS
POWERPOINTS AND ARE
NOT PART OF THE
UPDATED 2008 VERSION
MEMORY MAPS
Drought in
the Sahel
* * * * NEWS FLASH * * * *
MONDAY 22ND MARCH 1973
DROUGHTS HAVE PLAGUED THE LAND HERE IN THE SAHEL
STRETCHING FROM WEST AFRICA EASTWARDS FOR FIVE YEARS BUT
IS DROUGHT HERE REALLY THE PROBLEM?
• LAND USE PRACTISES HAVE CAUSED THE DEATHS OF MORE
THAN 100,000 PEOPLE
•
OVER 12 MILLION CATTLE HAVE DIED
• SOCIAL ORGANISATIONS HAVE BEEN DISRUPTED ON A NATIONAL
SCALE
DESERTIFICATION
• What is desertification?
Desertification is when a desert gradually spreads to the
surrounding areas of semi-desert
The
SAHEL
The Sahel is located in the southern region of the Sahara
desert, Africa. Look at the following pictures. In pairs
discuss where you think the Sahel is located.
The Sahel regions are areas which experience
desertification.
Why does the Sahel suffer from desertification?
DESERTIFICATION
Increase in cattle
Increase in population
Deforestation for fire wood
Grassland grazed more intensively
Roots no longer hold soil together
Roots may be eaten as well as grass
Leaves no longer protect soil from weather
Less vegetation means less protection
from weather
Loose top soil blown away by wind
Loose top soil blown away by wind
(Soil Erosion)
(Soil Erosion)
= DESERTIFICATION
=
EFFECTS OF
DESERTIFICATION
YOU HAVE 5 MINUTES
FOR EACH TASK.
TASK 1 – DRAW A SPIDER DIAGRAM LISTING AT LEAST 8 EFFECTS OF
DESERTIFICATION.
EFFECTS OF
DESERTIFICATION
TASK 2 – I WILL SHOW YOU ON THE NEXT SLIDE A PHOTOGRAPH.
YOU ARE A JOURNALIST AND YOU MUST GIVE AN APPROPRIATE CAPTION
OR TITLE TO THE PHOTOGRAPH.
THE BEST CAPTION/TITLE WILL BE STORED WITH THIS PHOTO FOREVER
CAPTION NEEDED…
Construct a newspaper report detailing the drought affecting
sub-Saharan Africa
Writing a double page centre spread for either The Sun
or The Times newspaper.
You must include:
• What the terms ‘drought’ and
‘desertification’ mean
• A map highlighting the Sahel region
• The main environmental and human
causes of desertification
• The effects of drought on people,
animals and agriculture
• Suggestions for ways in which desertification
can be reversed
• Methods being used to help solve desertification
• Pictures to emphasise key points
What does
desertification mean?
The Sahel
The Sahel is a geographic zone of
about 5,000 km long and 300 km wide
along the southern fringes of Africa's
Sahara desert. Climate, agriculture,
and ways of life are relatively uniform
across national boundaries. The actual
borders of this zone are usually
defined not in political or geographic
terms, but in terms of mean annual
rainfall. In the north, where the Sahel
merges with the Sahara, annual rainfall
averages 200 mm. Along the southern
border with the Sudanian zone the
average is 600-700 mm (see Figure 1).
The chief characteristic of the Sahel
zone is that it is prone to frequent and
lengthy periods of drought.
Sahel – Natural Causes
Scientists are researching
how climate triggered
the drought in Africa's
Sahel, site of one of the
world's most devastating
famines, which has
caused widespread
starvation.
The Problem
This dryland belt stretches across
Africa and is under stress from
land use and climate variability.
In the area pictured above, thick
bush once stood. Now only
scattered Acacia are found.
Persistent, unchecked land
damage claims both soil and
vegetation, leaving little habitat
for the region's wildlife.
Ultimately, there will be no
resources here for people.
Impacts
Impacts
DESERTIFICATION
• What is desertification?
So, what is desertification?
The UNCCD defines desertification
as the degradation of land in arid,
semi-arid and dry sub-humid
areas. Desertification occurs in
arid, semi-arid and sub-humid
areas - where the soils are
especially fragile, vegetation is
sparse and the climate particularly
unforgiving. These areas are
inhabited by one fifth of the
world’s population.
What is desertification?
1/3 of the earth’s land surface (4 billion hectares) is
threatened by desertification, and over 250 million
people are directly affected by desertification. 24 billion
tons of fertile soil disappear annually. From 1991 to 2000
alone, droughts have been responsible for over 280,000
deaths; they accounted for 11% of the total water-related
disasters.
Causes
Climatic variations
High temperatures lasting for months create droughts that prevent the
vegetation from growing.
Human activities
Human activities leading to desertification are mainly related to
agriculture: overgrazing removes the vegetation cover that protects it from
erosion. Overcultivation exhausts the soil.
Deforestation destroys the trees that bind the land to the soil. Wood is the
principal source of domestic energy for lighting and cooking in many arid
areas.
Poor irrigation practices raise salinity, and sometimes dry the rivers that
feed large lakes: the Aral Sea and Lake Chad have shrunk dramatically in
this way.
The intensification of human activities brings an increased greenhouse
effect, causing global warming. Drylands are likely to be especially
vulnerable to rises of temperature during the 21st Century.
Poverty and desertification: the vicious circle
Economic pressures can lead to the over-exploitation of
land, and usually hit the poorest hardest. Forced to
extract as much as they can from the land for food,
energy, housing and source of income, they are both the
causes and the victims of the desertification.
International trade patterns are based on the shortterm exploitation of local resources for export, acting
against the long-term interests of the local people.
Poverty leads to desertification, which in turn leads to
poverty.
The impacts of desertification
Desertification affects all aspects of life, highlighting how much environment and livelihoods are interlinked.
Dead vegetation in drought-stricken area,
Environmental impacts
Because of the vegetation loss, desertification makes areas more flood-prone. It also causes the salt level in soil to rise, results in
deteriorating quality of water, and silting of rivers, streams and reservoirs.
Economic impacts
Desertification has huge economic consequences – the World Bank estimates that at the global level, the annual income foregone
in the areas affected by desertification amounts to US$ 42 billion each year, while the annual cost of fighting land degradation
would cost only US$ 2.4 billion a year.
Poverty and mass migration
Land degradation brings hunger and poverty. People living in areas threatened by desertification are forced to move elsewhere
to find other means of livelihood. Usually they migrate towards urban areas or go abroad. Mass migration is a major
consequence of desertification.
From 1997 to 2020, some 60 million people are expected to move from the desertified areas in Sub-Saharan Africa towards
Northern Africa and Europe.
Department for International Development
Drought in the horn of Africa Feb 2006 update
The Horn of Africa is facing its worst drought for
at least a decade. The Secretary of State for
International Development visited the region in
January 2006 and saw at first-hand the terrible effects
this is having.
The UK is at the forefront of the international
response. DFID has committed £35.9 million to the
immediate relief effort in the worst affected countries Ethiopia, Somalia, Kenya and Eritrea. We are helping
to provide food aid, water, health services and life
saving nutritional therapy for children. We stand ready
to do more, in these countries and the wider region.
We are also working to tackle the underlying causes of
the persistent food crises affecting the region, and
elsewhere in Africa. This includes a three-year
commitment of £70 million to the Productive Safety
Nets Programme which got underway in Ethiopia last
year and is helping millions of people fight hunger.
BBC News Online
Ethiopia strives to feed itself
As the United Nations discusses anti-poverty
measures, the BBC News website assesses how Africa
could meet the Millennium Goals in 10 years' time.
Here, Mohammed Adow investigates whether Ethiopia
will ever be able to feed itself.
Hundreds of hungry farmers line up at a relief
food distribution centre in Boricha district,
southern Ethiopia to receive their monthly
ration.
"I've a family of four and I used to support my family
by tilling the land. Because of the drought I don't have
anything to harvest from my land," says 66-year-old
farmer Waricha Chema, who like many in Ethiopia
entirely survives on food relief from the government
and aid agencies.
"I would have liked some more food, this is not
enough for the family, but I have no choice except
making use of this."
Ethiopia has long provided the world with an
unfortunate case study of the devastating effects of
hunger.
Since the 1984 famine in which an estimated 1m
people lost their lives, the country has emerged as
one of the most food insecure countries in the world.