Managing the effects of soil erosion
and desertification
Y11 Geography
1
Recall that soil erosion is one of the
main drivers of desertification
• So any way that reduces soil erosion and it
•
effects, can also help prevent and mitigate*
desertification.
Main ways to do this are:
 To reduce the ability of rain water to erode the soil
 To reduce the ability of the wind to remove the soil
 To increase the health of the soil by adding organic
matter, which also reduces the ability of the wind to
erode
* Moderate or counteract the force of the impact
2
The Sahel is a semi-arid to arid area of scrubland and
desert stretching mainly across the countries of
Ethiopia, Eritrea, Djibouti, Northern Nigeria and
Somalia. Desertification in the Sahel is progressing at
a disturbing rate affecting 2,500 hectares each year.
The reasons for desertification in
the Sahel are:
• Human - Large population increases in recent years – has
lead to overgrazing of the land to meet higher food
requirement. The increased energy requirements have lead
to deforestation as more firewood has been needed.
Environmentally unsound policies that do not forbid or
actively encourage activities that may lead to desertification.
Lack of education in agricultural policies and techniques
has lead to stripping the land of minerals and humus which
has not been replaced. 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.
•Environmental or physical factors - Long periods of
drought and short periods of torrential rain experienced by
the Sahel region, and some climatic change.
3
The Tanout area, situated just south of the Sahara desert, is one of the driest
inhabited places on earth.
The Eden Foundation was set up in 1987 in Dalli, Nigeria. It helps 2,500 families in 123 villages. The Eden Foundation helps farmers stop
desertification whilst at the same time increasing their yield. Eden’s solution is to bring them trees and bushes that can grow naturally in this dry area
and give food, even in times of need.
The Solution: Plant edible perennials among their crops. These stabilise the soil, holding it together and so preventing erosion by the
rains. They also shelter the crops and the soil from the wind, further preventing erosion and increasing the yield. One farmer in Dalli with shielded crops
produced 130 baskets of millet, which was 3 times as much as his neighbour whose crops were not shielded. The perennials often have extensive root
systems, which are encouraged to extend even further by the method of planting them by direct seeding, so planting them directly into the dry earth.
This means that they will grow slowly but be hardier as they will have even more spreading root systems than normal. The perennials chosen are mostly
local shrubs or trees such as the Ziziphus bush. These trees produce fruit once mature which are sold or eaten by the family. In 1998 the fruit produced
per family of the Eden Foundation was worth, on average, about Euros 2, by 2007 this had increased to Euros 74
Unprotected field
destroyed by wind
and erosion
Crops protected
from tree planting
By Craig
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Increased yield and profit
•
•
•
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Edens solution to this is handing out free seeds that
have been researched at their local field station.
They use direct seeding. This means when you plant a
tree directly in the ground, without watering it, it
will still be able to grow, even if the process is quite
slow.
These trees and bushes can grow naturally, without
irrigation or chemical fertilizers.
The farmers go to them of their own accord, and can
order the seeds they want for free. They then show
them how to direct seed, and offer any advice
needed.
Since 1991, Eden have helped over 2600 households in 134 different villages.
The tree’s given produce fruit that can either be eaten or sold.
"Thanks to our Eden trees, we've had food to
eat even though the millet failed. For the last
three years, we haven't had a single good rain
in our village and this year's harvest lasted
less than a month. Instead, my family has lived
from the Eden fruits on our field which gives
us food for the day. We depend on it, for
there is nothing else to eat around here.“ Musa Abari from Garin Farara
By Rebecca
5
Contour stone bunds trap organic material such as
leaves, whilst allowing water to trickle through. This
distributes water evenly over fields when it rains, and the
trapped organic material can be raked across the fields,
eventually turning to humus and so improving the quality of
the soil. 10,000 people in more than 500 villages in Mali have
been taught this technique, in these villages, collectively,
contour stone bunds have been used on more than 10,000
hectares of land.
UNDP United Nations Dry lands Project Sahel
education
Barriers to
stop wind
erosion of soil
By Craig
Sustainable planting and irrigation techniques
6
By Rosalie
The name for these stone walls are bunds
7
By Thomas
Digues Filtrantes
• Permeable rock dams (digues filtrantes). The structures are
typically long, low dams of loose stone constructed in
gullies and across valleys. Because they lack a spillway, the
dams force flood water to spread over their length, which
strongly reduces its erosive force. They also force water to
infiltrate: this results in large quantities of sediment being
deposited, often filling up gullies within two years – which
in turn creates favourable conditions for growing crops
where nothing could be grown before.
8
Contour Bunding, Burkina Faso
-In the 1980s, British Oxfam worker Bill Hereford suggested contour
bunding as a way of combatting desertification in Burkina Faso.
Contour bunding is the process by which lines of stones are
placed on slopes and contours to stop topsoil washing away
and help rainwater settle in.
By Zoe
9
Contour bonding is an
inexpensive and simple
solution for African farmers.
- Farmers self manage the process.
One disadvantage of contour
bunding is that it has
resulted in a lack of stones.
By Zoe
10
- In Burkina Faso, it has increased the awareness of careful land planning
,care of the environment and overall sustainability.
- Over 400 villages have participated in using contour bunding.
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The number of hectares of land reclaimed bunded has risen from 50 in
1982-83 to 8 000 in 1989 and it is estimated that thousands more
hectares of land has been bunded since.
By Zoe
11
By Thomas
Terracing
• Prevents rain fall from washing away top soil and nutrients.
• Cheap to build, only man power needed.
12
Terracing technology in Darfur
Positive Action
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•
•
By Thomas
Practical Action suggested a one-year demonstration farm showing the use of crescentshaped terraces in comparison with traditional terraces. All the necessary equipment
and tools were produced locally and volunteer farmers (men and women) were trained
in how to lay out and construct the crescent-shaped terrace.
Household crescent-shaped terrace catchments cover an area of 0.5 hectares, 100150m in length, with earth embankments of 0.75-1m high, and ditching laid in the back
of the terrace of 0.5m deep by 1m wide.
Twenty-five pioneer farmers in Azagarfa supported the demonstration by building
crescent- terraces for comparison with their traditional terraces. These were outside
the ITDGPractical Action farm, and built with the farmer's own time and money - risky
for them if the project failed. However, early in the rainy season results were already
showing. ITDGPractical Action observed that 20 terraces were changed to crescents, as
other farmers adopted the new technology, even before the demonstration was
complete.
Practical Action
Crescent shaped
terraces
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Results
By Thomas
Traditional terraces
Crescent-shaped terraces
Weak rectangular shape subjected to flood
washing, no drainage system
Stronger crescent structure resists flood
washing, drainage system allows run off water
Square shape can't follow land contours
Crescent shape follows land contours
Flood washing increases soil erosion and reduces Tolerance of flood washing avoids soil erosion
potential for water retention
and increases water retention
Crops can't survive over 10 days without rain
Crops can survive over 21 days without rain
No ditch
Ditch provides water for household use and for
animals for two months
Low yield
Higher yield (double the traditional yield)
Potential to harvest crops for 6 weeks
Potential to harvest crops for 12 weeks
Need regular maintenance
Maintenance not required
Crop stalks died after harvesting
Crops survive, shooting at the first shower of
the next rainy season and giving early harvest
in time to get higher market prices
Complete rebuilding required for next rainy
season, including costs of hired labour
Next rainy season requires maintenance only minimal labour required
Minimum of three showers can give harvest
Just one shower can give harvest
14
By Thomas
Planting Trees
• Roots bind the soil together and leaves provide shade and
intercept water.
• Cheap and long term solution.
• Provides fuel, wood and building materials.
15
The Great Green Wall
By Thomas
• Imagine a green wall – 15km wide, and up to 8,000km long – a living green
wall of trees and bushes, full of birds and other animals. Imagine it just
south of the Sahara, from Djibouti in the Horn of Africa in the east, all the
way across the continent to Dakar, Senegal, in the west.
• The building of this pan-African Great Green Wall (GGW) was approved by
an international summit in Bonn, to combat desertification (UNCCD).
• The GGW, as conceived by the 11 countries located along the southern
border of the Sahara, and their international partners, is aimed at limiting
the desertification of the Sahel zone.
• It will also be a catalyst for a multifaceted
international economic and environmental
programme.
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Great Green Wall
By Zoe
-In February 2011, the UNCCD (United Nations Convention to Combat
Desertification) approved the planning of a “Great Green Wall”
-The idea was initially thought of in the 1980s by Burkina Faso’s president
Thomas Sankara.
-The ”Great Green Wall” will consist of trees, birds and animals.
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By Zoe
The Great Green Wall is planned to be a continuous
green band - 8,000km long and 15km wide. It will
stretch from Dakar in the East to Djibouti in the West.
-It will be rerouted around mountains and rocky areas.
18
By Zoe
The aim is to limit desertification by planting vegetation.
- By doing this, it is hoped it will act as a catalyst for both environmental and
economic activity.
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It should help preserve water supplies especially in Lake Chad and provide
fruit and vegetables.
It is hoped it will help political stability of the countries in the Sahel region and
reduce poverty.
19
•
The Great Green Wall is a project
developed by the African Union to
face desertification in South Sahara.
It is the largest environmental
transformation in Africa and the
green belt of trees expands out
7,775km long and 15km thick.
The trees' shade and bulk help offer
crops relief from the overwhelming
heat and gusting winds.
Spans out across 11 countries of
Africa
The Great Green Wall
Constructed along the Sahel belt.
By Loy
20
The aim behind the Great Green Wall is to limit desertification by
planting all sorts of vegetation. Although it does mostly consist of trees,
there are some animals that inhabit the Great Green Wall.
The Great Green Wall aids in both environmental health and helps
farmers economically.
By Loy
21
Sahel - Mali
By Alesha
What is its living state?
Mali is one of the poorest countries in the world: 70% of its population lives
on less than $1 per day. Its population amounts to about 13 million. Due
to where the country is situated, semi-desert and desert are common.
This means that 80% of the countries population depend on rain-fed
agriculture, livestock and fishing to maintain there poor state of living. The
degradation of fertile soil, makes this increasingly difficult to do.
What is being done to help Mali deal with soil degradation?
One company that is trying to help is Sahel Eco. It is a non-profit making
organisation, that helps Mali to change the way they farm and cultivate
crops, just in sandy, infertile soil. They support the local community by
training and building. This teaches the people, to better manage and
maintain the natural resources on which they depend. Along with this
Sahel eco works along with governments and Research Institutes to get
the best possible out come for the community.
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By Alesha
What is the purpose of this project?
The purpose of this project is to increase the numbers of trees on agricultural land and
by doing so, to reversing the effects of desertification on rural and urban
livelihoods in Mali. Sahel Eco do this by promoting the adoption of tree
managements that are simple and low cost. This can quickly allow for quick reforestation and benefit many of the community.
What problem does it address?
Desertification is one of the primary causes of poverty and under development in
Africa. The constant cutting down of trees, for fuel and basic timbre leaves the
fragile soil exposed to water and wind erosion – which are common in the farming
season. In extreme cases, the fertile top soil can be completely stripped away. But
trees not only help farmer to protect soils and improve crop production, they also
provide them with timber, fuel, fodder, fruits, drinks, herbal medicines and raw
materials for weaving a variety of useful items including mats, baskets and hats.
Restoring the tree cover on village lands and ensuring that the trees are managed
in a sustainable way can thus make a major contribution to addressing the
interlinked issues of desertification and poverty in the Sahel.
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By Alesha
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By Rebekah
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• In the Sahel, there's a wide range of different
ideas being put into action to stop desertification.
One would be, the team of people named 'Naam'
are travelling Africa planting trees and all sorts of
plants. They are also testing new farming methods
and trying to bring down poverty. Not only Naam,
but lots of other everyday people are planting
trees too, to help encourage a healthy landscape.
• The Sahel, life is being brought back to the sands.
By Cameron
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By Rebekah
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By Rebekah
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By Rebekah
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Using Pearl Millet in Northern Nigeria
By Loy
Pearl Millet is a breed of crop seed that is much more drought tolerant and
has a little earlier maturity. It also tolerates low soil pH better than sorghum.
This aids in managing and combating desertification in Sahel in many ways.
Pearl Millet helps increase the
average crop yield for farmers in
Sahel.
There are also few other breeds
of crop seed that have similar
features as Pearl Millet. See on
next slide.
Here are 4 other crops that are
like Pearl Millet. These crops are
drought resistant, climate
change-ready crops.
30
Desertification in India
http://www.caritas.org/activities/climate_change/desertification_in_india.ht
ml
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Half the land in India is now desertified due to overgrazing, shifting
cultivation without enough recovery time, industrial and mining activities,
unsustainable water management etc…
This is a big problem, because even though India is only 2.4% of the worlds
land area, it supports 16.7% of the worlds population and 18% of its
livestock.
To help this situation, parts of India use the ‘ridge and furrow’ system in
the black soil areas. This will help reduce the problem of water logging.
The furrows are small parallel channels, made to carry water to irrigate the
crop, which are usually planted in the ridges.
(This slide is pretty rubbish, but I
thought id keep it in just so you
could see lol!
My other desertification solution
is on the next slide )
By Rebecca31
Desertification in China
•
By Rebecca
Desertification in China is mostly due to over planting, overplowing and
overgrazing;
overgrazing – In inner Mongolia the livestock increased from 2 million
(1977) to 18 million (2000). This stripped the land of vegetation,
allowing the wind to then blow off the top soil, turning one third of the
grasslands into desert. If something isn’t done, it will all be desert by
2020.
•
China is very keen to get rid of desertification, with many different
solutions.
• For the overgrazing problem, fences have been put up and herders are
encouraged to take good care of the land. The government have asked
them to cut their flocks by 40%, but the herders aren’t too happy with
this.
• They are planting a line of trees and shrub across from the great wall
of China to protect farmland. This will eventually cover 4,000 miles in
length.
• The Chinese government has encouraged the planting of drought
resistant trees such as pines and poplars. In some places the farmers
are paid to plant them!
• Migration is huge in china due to desertification. Millions of people have
32
to abandon unproductive land with sand drifting their way.
• In China, they are doing the same. Its difficult to
rejuvenate lavish lands, however with enough
effort, money and time it is possible. Planting is a
very simple and effective way of wiping the
deserts clean, thus making it most popular. In any
desertification, people tend to adopt the same
methods as it isn't an easy challenge, nor is there
many ideas.
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By Cameron
By Rosalie
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By Rosalie
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Combating desertification in the
UAE
UAE
Sahel
By Craig
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The problem
The UAE lies across the Tropic of Cancer, it is one of the hottest areas of the world. Desertification and salinity of soil is
threatening local farms and is destroying the natural habitat of local species. The meagre volume of rainfall the Emirate
receives annually is not enough to meet the excessive and growing demands.
A Solution
Greening the desert: Greening The Desert is concerned with converting the natural desert environment into
productive agricultural land, conserving its biodiversity and increasing its economic outcome. The UAE efforts in
Greening the Desert increased the agricultural area from only 2.4% of the land area in the UAE to 6.5% of cultivated
land by the year 2000. As of 2005, 330,000 ha area has been planted through afforestation project in Abu Dhabi
Emirate to reduce sand movement and to enhance the environmental quality. Additionally, the government allocated
funds to monitor the shortage and imbalance of the underground water that will help in future planning of agricultural
activities.
Trials carried out in Abu Dhabi, have demonstrated the potential of biodegradable 'Eco-Flakes' to retain
water, promote plant growth and potentially help in 'greening' the desert. The flakes, which are based
on a polymer of urea, are 100% biodegradable and are manufactured to different pore sizes depending
on the final use of the product. In dry soils, for example, smaller pores are required for optimal water
absorption and retention.
After 20 days the
plants which were
grown with EcoFlakes were 100%
taller
By Craig
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By Craig
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Hydrophobic Sand
Waterproof nanotechnology sand to help green the desert. Emirati engineer Fahd Mohammad
Saeed Hareb peers into a bubble of water atop a tiny pile of sand cupped in his hands. Amazingly,
the water bubble does not drain through the sand – it remains intact, jiggling like crystal clear Jelly.
This is waterproof sand – or as German scientist Helmut F. Schulze calls it – hydrophobic sand, a
nanotechnology wonder seven years in the making. Another way to green the desert and beat back
shifting dunes of desertification. With new hydrophobic sand in place, traditional watering of desert
plants five or six times a day can be reduced to one watering, saving 75 per cent more water, a
precious resource that is dwindling across the Arab Peninsula.
By Craig
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