Download The Sahel Region

Introduction to managing
desertification and soil
erosion
What are the issues?
• As we have seen soil erosion often goes hand in
•
•
•
•
hand with desertification
So by tackling one you can effect the other.
Soil erosion can occur due to water in the form
of sheets and gulleys and also the wind, and can
be made worse by human activity.
Desertification can occur where there is soil
erosion and the rainfall is variable.
If you can reduce the erosion, the soil structure
and quality can be maintained and so
desertification is less likely to occur.
So what are the ways of tackling these
joint problems?
• Soil erosion by water is more likely to happen if the rainfall is very
heavy, particularly after a drought,
• But if the ground has structures in place to reduce run-off, the
erosion will be far less damaging
• There are 2 main routes to achieve this:
 Have perennial plants – trees and shrubs – which will help
hold the soil down, and act as a barricade to catch the soil
that is being washed away.
 Have a barrier to catch the water as it flows down the
slope carrying the soil.
 Keeping ground cover at all times to prevent the water
washing the soil away
So what are the ways of tackling these
joint problems?
• Wind erosion occurs after a prolonged drought,
•
when there is little remaining root structure to
hold the soil in place and not much organic
matter in the soil to act as a sponge to any
residual moisture
The solutions are similar to prevent erosion by
water:
 Have perennial plants – trees and shrubs – which will
help hold the soil down, and prevent the wind whipping
it away.
 Improving the ability of the soil to retain moisture so
it less easily blown away by measures including adding
organic matter
So many of the solutions will be
variations and combinations of
Planting trees and shrubs
Adding barriers to reduce erosion
Retaining the water in times of heavy rain
Adding organic matter to the soil, so that it
can retain water and provide plant nutrients
 Not leaving the soil as bare ground at any time
There are specific ways in which these ideas are
implemented that vary from place to place and
are adapted to the particular circumstances. It
is these examples we are looking for.




•
The Sahel Region
By Akram
Akram has explained the problems well and
suggested the direction for solutions without giving
any concrete examples
What is the Sahel?
• The Sahel is the region between the Sahara and
the Savannas in Sudan and Chad.
• It runs 2,400 miles from the Atlantic Ocean and
creates a belt all the way to Red Sea.
• Mostly covered in grassland and savanna.
The threat of desertification
• A United Nations Environmental
Programme shows that 6.1 billion
hectares of land on Earth is dry
desert.
• Areas that are Sahel regions are
vulnerable to becoming desert.
• A UNEP publication confirms that
the natural green belt extends across
the Sahel. It exists because it is closer
to the desert than the agricultural
zone and therefore too dry for
sustainable millet production.
Careless use, however, could easily
destroy this zone.
Maradi Niger by Emilie
• This is one example I had come across
and I think it is a really neat one – and
very effective as you will see
Maradi Niger
What is FMNR??
• FMNR is a self – promoting reforestation
system. This system started when the
farmers cut down the tropical rainforest
and made it into fields which led to soil
erosion. Now though instead of chopping
the stems, that grow from the underground
tree stumps, they let them grow and use
them for firewood and timber.
The benefits and problems of
this system.
•
•
•
•
Benefits
The firewood and building
timber the farmers get is good
quality and is good for sale or
personal use.
Fertile fields can be regained
because this system helps to
improve the soil.
Increases biodiversity so that
animals who lost their homes
when the rainforest was
destroyed can start to move
back.
Income generation – farmers
are able to sell the firewood to
make money to support their
families.
Problems
• Some of the fields may not
produce shoots from the
stumps.
• In very dry areas the shoots do
not grow very quickly.
FMNR in action.
• FMNR has
transformed the
landscape to provide
a workable method of
reversing the
devastation caused
by desertification
Now here are several examples from
other classes that came in too late for
their lessons so I thought I would add
them to the library of ideas and share
them with you too
Made by Chan
Zimmermann
Why is there desertification and soil
erosion in the region of Sahel?
The Sahel region is a semi-arid region that it turning into a
desert. The desertification is caused by the human being
and the environment
Desertification caused by humans: They have left the
animals graze the land and that destroyed the vegetation.
They have cut down trees and bushes for fuel, making the
land lose water. Lack of technology for agriculture. No
environmental policy, urban and industry activities.
Desertification caused by nature: climatic changes like
temperature, lack of rain, etc...
Solution for the
desertification and erosion
in the Sahel (1)
One solution that there are doing is the migration
to another place. The migration is a good idea
because it will stop desertification in a way or
slow it down by less over grazing,
deforestation, a good idea because and over
cultivation. But lots of people, like farmers and
people with a job, don't leave because they
would loss there job.
The UN and aid organisations have helped the
local people by giving them money and
shelters and schemes them get along.
Solution for the
desertification and erosion
in the Sahel (2)
In the windy areas, the faces of sand dunes can
be covered by large boulders or oil to keep
the sand from moving.
Sand fences can be built in the same manner that
snow fences are used in the northern United
States.
Plants can also be irrigated and grown at the base
of sand dunes. Since the plants bind the soil,
this helps prevent erosion and stop the
blowing sand.
Photos of the Sahel region
India
Desertification is a major problem in the
drylands of India, affecting the way of life
for its inhabitants. The problem is more
severe in the arid lands in the north-western
part of the country. The ones more affected
by the desertification are Haryana,
Lot of organizations have carried out
researches for better technologies to
counter the ill-effects of desertification in
india
Solution for the
desertification and erosion
in India
Wind Erosion Control: A number of mechanical and
chemical methods are available globally for the control of
wind erosion, but looking to the fact that this desert is highly
populated and has a dominantly agricultural economy,
rather than nomadic and pastoral one, many of the
mechanical and chemical methods of control can not be
implemented.
So far, the large-scale wind erosion control measures in India
have been sponsored by the Government. Farmers protect
and manage their fields especially through crop residue
management and fencing during critical periods. Two major
activities of wind erosion control are sand dune stabilization
and shelter belt plantation.
Solution for the
desertification and erosion
in India
Soil and Water Conservation: To counter
crusting of soil and its subsequent erosion from
the agricultural fields a number of practices
have been suggested. In the black soil areas
ridge and furrow system may help to reduce the
problem of water logging, while in the hard pan
soils deep ploughing at 3-4 years’ interval will
ensure better infiltration and root growth. Mixing
crop residues and organic matter with light
textured soils help to increase the soil moisture
and crop yield.
This is part of one from Ross
He did some good stuff on FMNR
which I will leave in the PP on the
wiki
How desertification is being managed in Spain
Spain was the first industrialized country to act on
the recommendations of 1977 Nairobi Conference
on Desertification. Spain has been restoring
degraded land for well over 100 years and since
then it is estimated that 5 million hectares of land
has been reforested, to prevent soil erosion.
Many different measures have been implemented
like, making sure no water is wasted and water
usage is not excessive. Also obliging farmers to
follow a code of good practices. In addition, forest
fires are commonplace, so a 10 million euro fund
has been set up so these can urgently be replaced.
In the centre of Spain, there is very often droughts
and water shortages. This means that the
management of water is a very big issue. One that is
being tackled by many different organizations and
groups.
For people living in the centre of Spain,
desertification must be reversed if they are to keep
their livelihoods.
This is from Alec
A series of really useful thoughts
The American
problem
In America there used to be massive herds of
bison which would stay clustered in tight
herds for safety from predators. Their hooves
and urine killed the moss while desirable
plant seeds were pounded into the soil to
germinate and also pounded organic
materials into the soil which aided plant
growth.
The bison would then move on allow the plants to grow, preventing
desertification. However because now there are cattle ranches
with cattle roaming unopposed by predators and free to roam and
do not trample and destroy the weeds and other inedible plants
that like the bison did and this blocks sunlight and reduce plant
growth. They also do not tread organic matter into the soil as they
are sparsely spread out and this means there is less water
retention in plants and less plant growth. This is creating an
American Sahara However Don and Cleo Shaules, near Billings,
Montana, have embraced a new idea of using cattle to do the job
the bison's once did.
The American
solution
By mimicking the historical sequence
of grazing with the aid of carefully laid
out fences, to put more animals in
smaller spaces for shorter periods of
time. They also herd the animals, or
put feed or supplements in areas
where the impact is especially
desired. The impact of the animals
effectively breaks down old plants
while also effectively ‘immunises’ the
landscape with bacteria in the form of
manure.
With heavy animal impact the Shaules have successfully trampled cactus and
sagebrush into the dirt, while "rototilling" the soil to favor new seedlings. The rich, brown
soil humus increased from 1/4 inch up to 1 1/2 inches in just ten years, and the Shaules
have been able to more than double their livestock numbers.
“We wintered our "herd" of one cow on the most brittle, erosion-prone part of our land.
Hay was put out in a different spot each day, and any that was not eaten was trampled
into the ground, resulting in an explosion of new seedlings and growth in spring.”
Afforestation
in the Sahel
Farmers in the Sahel are reclaiming the desert by
turning its barren wastelands into green, productive
farmland, that could potentially be used as a base
for bio-energy feedstock production.
Satellite images taken this year and 20 years ago show that the desert is in retreat
thanks to a resurgence of trees. Which are mainly ana trees (Faidherbia albida), a type
of acacia, which is itself a kind of energy crop. Wherever the trees grow, farming can
resume. Tree planting has led to the re-greening of as much as 3 million hectares of land
in Niger, enabling some 250,000 hectares to be farmed again. The land became barren
in the 1970s and early 1980s through poor management and indiscriminate felling of
trees for firewood, but since the mid-1980s farmers in parts of Niger have been
protecting them instead of chopping them down. By also combining the project with
simple measures such as ditches and holes to catch scarce rainwater and save it for
irrigation, the programmes are helping communities in Niger re-establish control over
desertification, simultaneously halting the march of the desert and helping to prevent
famines like the one that hit Niger in July 2005.
“Where 20 years ago there was barely a tree, there are now 50 to 100 per hectare.
Production of cereals has soared”
Managing irrigation and natural
waterways in North Coast
Orchards
This project was part of a wider project to
combat soil erosion in the North Coast of
Australia which is badly affecting
landowners there.
The site helped in the project was an old
macadamia orchard which had been
established with little regard for natural
watercourses. As a result there was
extensive sheet erosion with exposed
tree roots, and gullies had formed where
water flows concentrated in the orchard.
The damage to the orchard floor meant
machine-harvesting in those areas of the
orchard was ineffective. The new
landowner of the site wanted to reduce
the dramatic soil loss and improve
machine-harvesting while maintaining
existing production levels.
The Solution
Firstly gullies running down between the lines of trees were
filled with large gravel. Some trees in the way of natural flow
lines for water, and also trees which over-shaded areas
stopping sunlight getting through to the grass, were removed
and others pruned to help grass to grow over the top of the
gravel, which would allow machine-harvesting. The filled
gully functioned as both a subsurface and surface drain
which allowed water to flow across the tree rows and small
rock check dams were installed to slow the water down and
encourage sediment deposition rather than the water just
washing the organic matter out of the orchard.
After the scheme the land’s active gully erosion and sheet
erosion through the orchard had been greatly reduced by
slowing the water flow and allowing sediments to improve
the soil structure and resist soil erosion. The extra light
from removing specific trees also improved groundcover
and because sediments were being trapped within the
orchard, rather than ending up in dams and watercourses,
the soil composition and structure benefited and plants
were able to obtain the water and nutrients they needed.
Another positive of the scheme was that the orchard’s
production was not been interrupted or set back by the
erosion control works so the landowner really ended up
with a win/win situation.