Department of Physical Geography – Utrecht University
Department of Physical Geography – Utrecht University
Desertification: land degradation in arid lands
Today’s program:
Lecture:
Land Degradation/desertification in arid & semi arid regions
Exercise:
Land degradation & remote sensing: discussion
Within 2.5 weeks:
Handing in the exercise and Sahel essay
Morocco, May 2005
Department of Physical Geography – Utrecht University
Department of Physical Geography – Utrecht University
Desertification:
What is a desert?
What is desertification?
According to Thomas & Middelton:
The diminution or destruction of the biological potential
of the land that can lead ultimately to desert-like
conditions.
According to UNCCD (www.unccd.int),
United Nations Commission to Combat Desertification:
Desertification is the degradation of land in arid, semi-arid and dry
sub-humid areas. It is caused primarily by human activities and
climatic variations.
Department of Physical Geography – Utrecht University
Department of Physical Geography – Utrecht University
What is a desert ? What is arid land ?
What is a desert ? What is arid land ?
Various criteria exist e.g.:
Aridity Index (Thornwaithe 1948):
ratio of annual precipitation and mean annual potential evapotranspiration
Aridity Indices e.g. of Bodyko or Thornwaithe :
a numerical indicator of the degree of dryness of the climate at a given location
Biological criteria:
Based on arid-adjusted life forms (plants)
Satellite-based criteria:
Based on mapped biomass from satellite imagery
Arid Regions:
Hyper arid:
Aridity Index
P/PET
< 0.2
0.05 – 0.20
Surface Area
10 x 106 km2
16.2 x 106 km2
% of World Total
7.5 %
12.1%
Aridity Index (AI):
a numerical indicator of the degree of dryness of the climate at a given location
AI serve to identify, locate or delimit regions that suffer from a deficit of
available water, a condition that can severely affect the effective use of
the land for activities as agriculture or stock-farming
Department of Physical Geography – Utrecht University
P/PET diagram
Department of Physical Geography – Utrecht University
The situation in The Netherlands
Avg Annual P:
792 mm
Does this site
has an aridity index
of P/PET <0.2?
Avg Annual E-act:
501 mm
Avg Annual surplus:
291 mm
Where is this area
located on the globe?
But NL has a water
deficit each summer
irrigation required
for a good yield
N/S hemisphere?
New Orleans
P: 1574 mm
T: 21.1 ˚C
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P - PET - AET relation also used in
Agricultural Land Evaluation Assessment (FAO, 1995)
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UN-FAO LADA Project Land Degradation Assessment
Identified climate hot spots based on P/PET
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Desert zone: region of maximum difference PET/P
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Other criteria for desert areas: satellite-based mapping on the presence
of green biomass indices
Desert Biome based on NOAA-AVHRR
Normalized Difference Vegetation Index (NDVI) Values
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Other criteria for desert areas: life forms.
Desert Biome based on presence of desert vegetation, sclerophyllous life forms
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Köppen Climate System (most widely used classification system):
Bw: Dry, Desert (German: wüste)
Bs: Dry, Steppe
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Köppen BWh (dry desert hot) versus Cfb (Mild mid-latitude climate)
h: low latitude, heiss
k: mid-latitude, kalt
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Desert (UNEP, 2006, Global Deserts Outlook):
a region with little vegetation cover and large surfaces of exposed
bare soil where average annual rainfall is less than 20 % of
the amount needed to support optimum plant growth.
Plants and animals show clear adaptions for survival during long droughts.
Desertification is normally associated with the margins
of existing deserts such as the Sahel or Gobi.
The Dust bowl in US Great Plains was not at such margins.
note differences in rainfall and temperature
Department of Physical Geography – Utrecht University
Department of Physical Geography – Utrecht University
Several reasons for this 1970 catastrophe are described:
Desertification became on the world’s agenda in the late sixties
Sahelian drought:
- Six year drought 1968 – 1974
- Vegetation disappeared,
- Millions of livestock perished
- Thousands of people died
- Enormous migration out of the Sahel into large cities and southwards
Sahel:
- About 10 countries at the southern edge of the Sahara:
Senegal, Mauritania, Mali, Burkina Faso, Niger, Nigeria, Cameroon,
Chad, Sudan, Ethiopia
- Dimensions:
East – West: 4800 km
North – South: 400 to 800 km
Less rainfall during 6 years
Destruction of traditional life by the late colonial occupiers
traditional life: nomads herding goats
migrating in the ITC (intertropical convergence zone) i.e.
following the rain and the resulting biomass
crop growth limited to favoured river valleys
Enormous population growth in the 60s and 70s:
humans and livestock numbers soared
due to western aid, improved medical conditions
above average rainfall before the 1968 drought
Economic and political changes:
dryland farming and irrigation practices
tilling soil that was not suited for agriculture
Enormous demand for fire wood: cooking & heating
elimination of most trees in the Sahel zone
Overgrazing removed grasses and shrubs
Department of Physical Geography – Utrecht University
Department of Physical Geography – Utrecht University
Why does the Sahel suffer from desertification?
Factors and Processes of Soil Degradation
DESERTIFICATION
Increase in population
Increase in cattle
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)
Lal, Hall & Miller, 1989
Department of Physical Geography – Utrecht University
Average annual rainfall in the Sahel zone
Fragile zone for desertification in green
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Mean annual rainfall in the Sahel zone in 1972
Isolines of 200, 600, 800 mm, ~ 150 to 200 km more south
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Mean annual rainfall in the Sahel zone between 1931 to 1960
Isolines of 200, 600, 800 mm
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Djebel Gehaniya Sudan in February 1980
Department of Physical Geography – Utrecht University
Department of Physical Geography – Utrecht University
Djebel Gehaniya Sudan in February 1984
Djebel Gehaniya Sudan in February 1989
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Department of Physical Geography – Utrecht University
The future for central and northern Africa looks grim for T (IPCC):
Disappearing snow cap
in 2075 global average temperature is +3 compared to 1990
of Mount Kilimanjaro
oC
Change in annual average temperature
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IPCC
Department of Physical Geography – Utrecht University
The future for P is better:
The future, trends:
- red areas: drier, blue areas: wetter
- uncertain future of annual distribution of precipitation
yields in 2050, % increase/decrease compared to 1990
mm
change of average annual rainfall in mm
% change in yield
IPCC
IPCC
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The past is the key to the future ……………..
Future conditions difficult to predict if we look to the past:
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Future conditions difficult to predict if we look to the past:
Shorter term:
Longterm:
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Future conditions difficult to predict if we look to the past:
Last centuries:
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Model future Predictions also differ significantly
2000-2049 Projected Rainfall Trends
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Backward modelling differ significantly
1950-1999 Simulated Rainfall Trends
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Droughts in the Sahara probably behave cyclic ……
The Great Sahelian drought was not a special event in history
Water levels in Lake Chad (one of very few longer records):
1913
1944
1972
Department of Physical Geography – Utrecht University
Department of Physical Geography – Utrecht University
Lake Chad, Central Africa: retreating shore lines from 1963 to 1997
Different approaches of monitoring /looking at desertification
• Timeseries of rainfall records
• Uncertainty of annual rainfall (deviation of the longterm mean)
• Counts of livestock
1963 Argon Satellite
1973 Landsat MSS
• Changes/spatial shifts in land use / land cover
• Biomass productivity of the land, most often derived from
satellite imagery: NDVI timeseries
• Combination of rainfall and timeseries of NDVI
• Direct monitoring of available soil moisture using models and RS
1987 Landsat 5 TM
1997 NOAA AVHRR
Monitoring of natural variation is difficult:
short time series of satellite images, strong increase of irrigation (human impact)
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Effective ways to combat desertification:
Department of Physical Geography – Utrecht University
Over the last 30 years
10 billion us$
has come as western aid
to this region
• Reduce overgrazing
• Reduce deforestation, increase reforestation
• Reduce destructive forms of irrigation (salts) and mining
• Rational land use i.e. no over exploitation of soil resources
Most is immediate famine relief
without long-term positive effect
There are only a few positive
results of UNEP, and others,
actions of soil and water
conservation measures
• Restoring soil fertility and structure by planting trees and grasses
anchoring the soil and holding water
Department of Physical Geography – Utrecht University
Department of Physical Geography – Utrecht University
Good development indicator?
A side jump:
Children with growth deficit (under height for age)
How to assess development status in the world ?
What is a fair indicator ?
Why important?
Because development status goes often hand in hand
with land degradation issues
Stunted growth is an indicator for malnutrition at young age.......
Department of Physical Geography – Utrecht University
Department of Physical Geography – Utrecht University
Good development indicator?
Good development indicator?
Percentage of population (per country) living under $2,- per day
Percentage of population with access to safe, clean drinking water
Department of Physical Geography – Utrecht University
Department of Physical Geography – Utrecht University
Good development indicator?
Land area map
Expected agricultural yield for cereals given high inputs (fertilizer, irrigation)
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Finally a different global pattern .........
Department of Physical Geography – Utrecht University
•
Department of Physical Geography – Utrecht University
Primary Education
Total children
•
•
Worldwide, children make up a third of the population. In 2004 there were 1,826 million children aged
under 15. Only children under 15 are shown in this map and graph. Africa has the highest percentage of
children. In Uganda and Niger half the population is under 15 years old. In Italy, Spain and Japan only
14% of the population are children aged under 15.
The land area of each territory is shown here.
The total land area of these 200 territories is 13,056 million hectares. Divided up equally that would be
2.1 hectares for each person. A hectare is 100 metres by 100 metres.
However, population is not evenly spread: Australia's land area is 21 times bigger than Japan's, but
Japan's population is more than six times bigger than Australia's.
•
"Everyone has the right to education", according to the Universal Declaration of Human Rights. The
second Millennium Development Goal is to achieve universal primary education. In 2002, 5 out of 6
eligible children were enrolled in primary education worldwide. However, enrolment does not guarantee
attendance, or completion.
If primary education continues beyond the expected years, enrolment rates can exceed 100%. In
Argentina there is an impressive 108% enrolment. On the other side of the Atlantic Ocean 30% of
children in Angola are enrolled in primary school.
Department of Physical Geography – Utrecht University
Department of Physical Geography – Utrecht University
Secondary Education
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•
Worldwide approximately 73 million children are enrolled in each year of secondary education out of a
possible 122 million children. That is only 60% getting a secondary education.
In China on average 89% get a secondary education, but in India it is only 49%. Figures in Africa are
even lower: 45% in Northern Africa, 25% in Southeastern Africa and 13% in Central Africa. The lowest is
5% in Niger. What is compulsory in some territories is a rarity in others.
Department of Physical Geography – Utrecht University
Tertiary Education
•
The highest percentage of the student aged population enrolled is in Finland. Finland is 3.6
times the world average, with 140 times the chance of a tertiary education than in
Mozambique.
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HIV Prevalence
Books borrowed
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This map shows books borrowed from public libraries - which lend books to members for free or for a
nominal charge. Libraries share books, making it unnecessary for us to buy books that we will read only
once or twice.
The most books borrowed were in the Russian Federation. There were high rates of borrowing in
Western Europe, Japan and Eastern Europe. In these regions most territories reported some book
borrowing. In other regions reported book borrowing was lower, and many territories reported very little
borrowing. Where many people cannot afford books, it appears they often cannot borrow them either.
Department of Physical Geography – Utrecht University
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Department of Physical Geography – Utrecht University
Tuberculosis
Malaria cases
•
Of all the people living with malaria, 92% live in African territories. Parts of Mediterranean Africa have
very low numbers of malaria cases. In contrast, almost half the people living in Uganda suffer from
malaria. Uganda also has the most cases of malaria in the world. Most territories are barely visible due to
the low number of malaria cases found there.
This map shows the number of people aged 15-49 years old living with HIV.
In 2003, the highest HIV prevalence was Swaziland, where 38%, or almost 4 in every 10 people aged 15
to 49 years, were HIV positive.
All ten territories with the highest prevalence of HIV are in Central and Southeastern Africa.
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The World Health Organisation reports that someone with open tuberculosis would infect 10 to 15 people
a year. So when a certain number of people are infected it is very hard to stop it spreading further.
Tuberculosis bacilli are spread through the air when someone sneezes or coughs.
In the past 50 years drugs have been developed to treat tuberculosis. The disease has since developed
strains that are resistant to those drugs.
Department of Physical Geography – Utrecht University
Department of Physical Geography – Utrecht University
Science Research
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Scientific papers cover physics, biology, chemistry, mathematics, clinical medicine, biomedical research,
engineering, technology, and earth and space sciences.
The number of scientific papers published by researchers in the United States was more than three
times as many as were published by the second highest-publishing population, Japan.
There is more scientific research, or publication of results, in richer territories. This locational bias is such
that roughly three times more scientific papers per person living there are published in Western Europe,
North America, and Japan, than in any other region.
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Research and Development expenditure
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Department of Physical Geography – Utrecht University
New Patents
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In 2002, 312 thousand patents were granted around the world. More than a third of these were granted
in Japan. Just under a third were granted in the United States.
A patent is supposed to protect the ideas and inventions that people have. Patenting something will then
allow the owner of the patent to charge others for the usage of an idea or invention. The aim is to reward
the creator for their hard work or intelligence. But patents can prevent people from using good ideas
because they cannot afford to do so.
A quarter of all territories had no new patents in 2002, so will not profit from these in future years as
others will.
Department of Physical Geography – Utrecht University
Ecological Footprint
• Resource accounting tool used as management / communication tool
by governments, educational institutions and NGOs to answer
• How much of the biological capacity of the planet is required
by a given human activity or population?
Calculation method of the Ecological Footprint:
• The Ecological Footprint of a person is calculated by considering
all of the biological materials consumed and all of the biological
wastes generated by that person in a given year.
• All these materials and wastes are then individually translated into
an equivalent number of global hectares.
In 2005, the average biologically productive area per person worldwide
was approximately 2.1 global hectares (gha) per capita.
Research and development is what scientific and technological and medical companies engage in to find
new designs. This can be an expensive pursuit, given the costs of materials, machines and skilled
specialists. Yet the development of a new design can bring financial rewards, as well as the benefits of
developing a new medicine, gadget or piece of software.
In 2002, US$289 billion was spent on research and development in the United States; in the same year
there was practically no research and development spending in Angola.
Telephone lines
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In 2002 there were just over a billion mainline telephones worldwide. This is almost double the number in
1990. The six territories with the most mainlines were located in different regions, they were: China, the
United States, Japan, Germany, India and Brazil. The fewest mainlines were in Andorra and Niue.
As in 1990, by 2002 the regions where the most mainlines per person were found were North America,
Western Europe and Japan. The largest increase in mainlines per person, however, was in Eastern Asia.
There were roughly ten times more mainlines (in total and per person) in Eastern Asia in 2002 than in
1990.
Department of Physical Geography – Utrecht University
Department of Physical Geography – Utrecht University
World map of the avg ecological footprint
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Desertification: Exploding the Myth
1994, David Thomas & Nicholas Middleton
Expressed in global hectares
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In the Dutch newspapers on 11 August 2004
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FAO ARTEMIS project
Monthly precipitation
&
‘Greeness’ indicess
Timely measures
might have
prevented this
grasshopper
plague
March 2004:
FAO announces extreme
many breeding places
in the Atlas mountains
Bron: http://metart.fao.org
Department of Physical Geography – Utrecht University
Department of Physical Geography – Utrecht University
Moderate climate of western Europe and the engine for rainfall in
Europe and Africa are the ocean currents
Spatio-temporal patterns of desertification/aridification
What are driving forces behind these processes
Ocean Surface Temperature
Atlantic Ocean
NW transport of warm water
along Nova Scotia
Department of Physical Geography – Utrecht University
Department of Physical Geography – Utrecht University
From process knowledge of ocean currents (ENSO & NAO),
We start to know when we might expect cyclic periods of
heavy rainfall or drought
NAO: Northern Atlantic Oscillation
El Nino Southern Oscillation
North Atlantic Oscillation
Sources:
http://www.ldeo.columbia.edu/NAO
www.jpl.nasa.gov
Department of Physical Geography – Utrecht University
Department of Physical Geography – Utrecht University
Northern Atlantic Oscillation Index
Time series of NOAA-AVHRR images are analyzed to investigate
the long-term greenness development of southern Europe/northern Africa
NDVI (greenness) temporal profiles were created to study dynamics
60
+
50
BareSoil
Water
Vegetation
_
Reflectance
40
NIR - R
NDVI =
30
20
NIR + R
NIR
R
10
0
400
NAO index negative --> droughts in southern Europe & northern Africa
This example (158 images):
time span: July 1981 until August 1994 (13 year)
cloudfree mosaics of 8 by 8 km pixels
Great Sahelian Drought
600
800
1000
Wavelength (nm)
Reference sites:
- Guadalentin, southern Spain
- La Peyne, southern France
- Crete, southern Greece
- Sahara of central Tunisia & central Lybia
Department of Physical Geography – Utrecht University
Department of Physical Geography – Utrecht University
Long-term change assessment based on Earth observation
Seasonal cycle of ‘greenness’ between 1981 to 1994
NDVI values for the 3 testsites and the Sahara
from July 1981 to August 1994
0,7
0,6
0,5
0,4
Guadalentin
0,3
La Peyne
Crete
0,2
Sahara
0,1
0
-0,1
-0,2
Month/year
Cloud free NOAA-AVHRR mosaics
Sahara is calibration site
Source: NASA Pathfinder set
Department of Physical Geography – Utrecht University
Department of Physical Geography – Utrecht University
What is special to the Mediterranean region ?
• Climate: summer drought & torrential rains
• Soils & lithology: soft sediments with high clay/silt content
• Rugged topography due to presence of several mountain ranges
The Mediterranean region as an example
of a semi-arid area under threat
Mmmh
• Volcanic hazard & earth quake hazard
due to geologic position at edge of plates
• Long-term land use & human occupation
• Strongly increased human occupation: tourism
• Strongly increased water consumption:
irrigation, population, tourism
• EU policy
Department of Physical Geography – Utrecht University
Department of Physical Geography – Utrecht University
One of the extremes: Guadelantin Basin, SE Spain
What is special to the Mediterranean region ??
Climate:
Mean annual temperature: 18o C
mean January temperature:
11o C
mean July temperature:
25o C
Mean annual precipitation:
300 mm (flats) - 500 mm (mountains); 760 mm in NL (De Bilt)
- very dry & hot summers
- main rainfall peak in Autumn (November)
- minor rainfall peak in Spring (April)
- severe moisture deficit in summer
- hardly any days with night frost (outside mountainous areas)
De Wit, 2001; Boer, 1999
Department of Physical Geography – Utrecht University
Resulting in a severe moisture deficit in summer…….
Department of Physical Geography – Utrecht University
Conditions for torrential rainfalls…..
• Genoa low/depression
• Mountain range location
& orientation
• Street of Gibraltar
• Warm sea water in Sept/Oct.
adds moisture to the depression
Ocean
depressions
Barry & Chorley, 1998
Department of Physical Geography – Utrecht University
Department of Physical Geography – Utrecht University
Example:
06.00hr on 12 November 1999 until 06.00hr on 14 November
the low pressure cell did not move for 36 hrs …….
Animation of global circulation
Carcassconne: > 620 mm in 36 hrs
Department of Physical Geography – Utrecht University
Department of Physical Geography – Utrecht University
Relation between soil types and topography in the Mediterranean
Mediterranean Soils
Mediterranean soils are highly varied but generally:
Thin & poorly differentiated in horizons
Stony, red, often calcareous
Differing organic matter content
Sometimes huge clay deposits/naps
They develop into badlands:
- Terres noires, france
- Calabria, Italy
- Thebes badlands, Greece
- Southern Guadelantin, Spain
Source: Allen, 2001
Department of Physical Geography – Utrecht University
Department of Physical Geography – Utrecht University
Mediterranean Soils
Mediterranean soils
Aggregates stability is often low
Soil sealing & crusting
- soil aggregates are destroyed
- particle fill the cracks
- compaction by rain drop impact
FAO Rendzic leptosol
Brown Medit. soil
AR of AC profile
Terra fusca
Rendzina
FAO Cambisol
A B R profile
Terra Rossa
FAO Cambisol
A B C/R profile
Adverse effects:
- reduced infiltration
- increases surface runoff
- rill & gully development
- hampers seed germination
- hampers plant settlement
- water retention of the soil is reduced
- soil aeration is reduced
Department of Physical Geography – Utrecht University
Department of Physical Geography – Utrecht University
EU developments
History
European growing awareness of
land degradation problems
Dust bowl in Kansas, Oklahoma
USA in 1937
The Sahelian Drought
From 1970 to 1985
Desertification & salinization problems
in Spain & Italy during the ’80s
Massive forest fires in the ’80s and ‘90s
Severe flooding events in the mid-’90s
Department of Physical Geography – Utrecht University
Department of Physical Geography – Utrecht University
Concept behind of EU strategy of Mediterranean degradation:
EU Actions research:
Research initiatives within 4th & 5th framework:
• Development of monitoring programs:
field measurements, Earth observation
timeseries of meteorological data
MEDALUS
DeMon
LADAMAR
POSITIVE
LUCIFER
Etc.
• Model development to:
- increase process knowledge of unfavourable processes
- to test & work out scenarios of extreme events
- to test & work out scenarios of human interference/land management
Climatic factors
Geomorphological
Factors
Torrential rainfall
Drought
Fires
Aridity
Soil & vegetation loss
Land degradation
Desertification
• Water balance studies: global, regional, local
• Socio-economic studies
- agriculture is rapidly losing its economic importance
from 1988 to 1995: No. of farms dropped by 4%/yr in France
- 75% of the farmers in France is 55 years or older
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Mismanagement or
Overexploitation
of resources
Human
Factors
Source: F. Perez-Trejo
Population pressure
Department of Physical Geography – Utrecht University
EU CORINE approach to assess land degradation:
EU actions in agriculture:
Using the USLE: Universal Soil Loss Equation
- developed for plot studies in the USA
- based on rainfall, soil (texture, organic matter, drainage),
crop cover, slope, management
EU common agricultural policy (CAP) aimed at:
• optimizing agricultural production
• scaling up of agricultural activities:
irrigation, pesticides, machinery, land levelling
Since late ’80 & early 90s’:
EU suffers from a surplus production in agriculture
Agricultural policy now stimulates:
• Set-aside regulations: fallow land
• Production of non-food crops but e.g. fuel crops
• Conversion of agricultrual land into forest or recreational areas.
De-forstation has come to an end in Europe
except for recreation purposes (ski areas)
Various scientific weak points in this approach ……
Economic importance of agriculture prevails over conservation measures
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Traditional Mediterranean land use system
Department of Physical Geography – Utrecht University
Early Agricultural Policy stimulated degradation:
Heavy & large machinery:
• soil compaction, reduced infiltration,
hampers germination
Large-scale irrigation:
• water shortages & salinization
Larger agricultural fields:
• stimulates runoff, enhance energy of surface
runoff & flooding
Abandonment of marginal lands:
• maintenance of terraces & drainage works stops
• triggers incision & formation of badland areas
Traditional system of land management and
extensive use has ceased
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Impact of EU subsidies starting in 1975
on the number of sheep & goats on Crete, Greece
Department of Physical Geography – Utrecht University
Modern Mediterranean land use system
Department of Physical Geography – Utrecht University
Example of unexpected results of EU subsidies:
After WW II:
• Land abandonment in Greece (isles, agricultural areas)
• People migrate to northern Europe & to the cities
Effect:
• Number of grazing sheep & goats significantly diminished
EU & government:
• land abandonment was considered unfavourable
• EU starts subsidies for cattle breeding in 1960s
Impact:
• strong increases since 1960 due to EU subsidies
and since early ’80s due to tourism
Department of Physical Geography – Utrecht University
Effect of EU agricultural subsidies (example of Crete)
Number of sheep & goats exceeds carrying capacity: overgrazing
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Department of Physical Geography – Utrecht University
Climate Change for the Mediterranean
Climate Change for the Mediterranean
Temperature:
Precipitation:
RCM prediction 2070
RCM prediction 2070
IPCC A2 (left):
Winter:
+ 2.5 °C
Summer:
+ 5.5 °C
Annual av: + 3.5 °C
IPCC A2 (left):
Winter:
+15 / -20 %
Summer:
-30 / -35 %
Annual av: - 2 %
IPCC B2 (right):
Winter:
+ 2.0 °C
Summer:
+ 3.0 °C
Annual av: +2.5 °C
IPCC B2 (right):
Winter:
+ 35 %
Summer:
- 20 %
Annual av: + 5 %
Gao & Giorgi, 2008
Gao & Giorgi, 2008
Department of Physical Geography – Utrecht University
Department of Physical Geography – Utrecht University
Climate Change in the Mediterranean
Synthesis:
Causes of Arid/Mediterranean Land Degradation Problems
Water Stress:
RCM prediction 2070
Climate:
strong seasonality, intensity, spatial variability of rainfall, hot dry summers
More water available
in winter up to +2 mm/day
Human-direct:
inappropriate land management, removal of vegetation, burning,
irrigation, industrialization, mining, water & air pollution,
urbanization, tourism.
Strong water shortage
in summer up to -4 mm/day
Human-indirect:
population growth & migration, rural de-population, loss of traditional land
management, long-term historic pressure, agricultural policy.
~ 60 to 80 mm/yr
less water available for
plant growth
Natural environment:
topography, soils are sometimes prone to erosion, aggregates, tectonics
Gao & Giorgi, 2008
Department of Physical Geography – Utrecht University
Department of Physical Geography – Utrecht University
Exercise Land Degradation & Remote Sensing
• About the use of NDVI & RS for land degradation / desertification monitoring
• An exercise to compute NDVI values for 2 images of Marroc
• An analysis of long-term development of NDVI in the Mediterranean
For 2 October (hand in, in my mail box 113 Zonneveld):
• Short answers to the questions 1 to 9 on the Sehoul case & Mediterranean
• Writing an essay of max 8 pages on the Sahel behaviour:
an interpretation of the Sahel expansion or contraction ?
on the basis of:
- 2 short Science papers
- 1 Global Change Biology paper
- Info on the website mapjourney.com/sahel
- Other relevant info that you find in the library or web.
Department of Physical Geography – Utrecht University
Department of Physical Geography – Utrecht University
What I expect:
4 sources of information for your essay:
• Work in small groups on the questions asked in the hand out
• Formulate carefully the answers to these questions
1
Science 253 (1991)
• Study the provided journal papers and website
• Hand in your answers to the questions & max. 8 page Sahel essay
2
Science 281 (1998)
3
Global Change Biology 12 (2006)
4 www.mapjourney.com/sahel
Department of Physical Geography – Utrecht University
Department of Physical Geography – Utrecht University
Department of Physical Geography – Utrecht University
ASTER
Department of Physical Geography – Utrecht University
Thanks for your attention
ASTER