Africa’s Lakes:
Atlas of Our Changing Environment
Ashbindu Singh
United Nations
Environment Programme
(UNEP)
as@rona.unep.org
Africa’s Lakes:
Atlas of Our Changing Environment
Africa’s Lakes:
Atlas of Our Changing Environment
Objectives
• Provide visual evidence of changes taking place in African lakes;
• Communicating scientific information to a wider audience in an
engaging fashion;
• Provide resources to educational community.
Assumptions:
Trends over time is the most compelling information
“A picture is worth a thousand words”
“Seeing is believing”
The Shrinking African Continent
Population per unit area
1950 - 7 people/km2
1960 - 9
people/km2
1970 - 12 people/km2
1980 - 16
people/km2
1990 - 21 people/km2
2000 - 27 people/km2
Africa’s Lakes:
Atlas of Our Changing Environment
Forest Loss, Invasive Species, Land Degradation, Pollution and
Inefficient Irrigation taking their toll
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CONTENTS
Over 60 Satellite Images
Over 40 ground photos
15 Environmental Maps
of Africa
CONTRIBUTORS
42 Contributors from 16
Organizations and 11
Countries
Africa’s Lakes Atlas of Our Changing Environment
Africa’s Lakes:
Atlas of Our Changing Environment
“Before and after satellite images”
Case studies
1.
2.
3.
Lake Chad, Nigeria, Niger,
Chad, Cameroon
Lake Victoria, Uganda,
Kenya, Tanzania
Toshka Project, Egypt
•
Lesotho Highlands Water Project,
• Lake Nakuru, Kenya
• Challawa Gorge Dam, Nigeria
• Lake Kivu, Congo/Rwanda
• Lake Alaotra, Madagascar
• Lake Al Wahda, Morocco
• Lake Cahora Basa, Mozambique
• Lake Chivero, Zimbabwe
• Lake Djoudj, Senegal
• Lake Ichkeul, Tunisia
• Lake Manantali, Mali
• Lake Sibaya, South Africa
• Songor Lagoon, Ghana
• Lake Tonga, Algeria
Africa’s Lakes Atlas of Our Changing Environment
Africa’s Lakes:
Atlas of Our Changing Environment
•
Lack of good database makes precise number of lakes in Africa
unknown, but according to the WORLDLAKE database, there are
677 lakes in Africa (Minnesota State alone is home to 10 000 Lakes)
•
There are 15 natural lakes that cross the political boundaries of two
or more countries in Africa
•
There are 60 transboundary river basins in Africa, covering over
63 per cent of the continent’s land area
Lake Chad’s surface area has shrunk by 95 per cent over the past 35
years
•
1960
1970
1980
1990
Africa’s Lakes Atlas of Our Changing Environment
Africa’s Lakes:
Atlas of Our Changing Environment
•
Uncontrolled damming, the withdrawal of water for irrigation, and
climate variability are the major causes of drying up of Lake Tonga in
Algeria
Population growth around Lake Victoria, the continent’s largest
lake, is significantly higher than the rest of Africa
•
Some lakes in central Africa have become known as “killer lakes,”
because of the catastrophic natural events that have occurred in
their vicinity
•
2000
2005
2010
2015
PROJECTED
Africa’s Lakes Atlas of Our Changing Environment
Shrinkage of Lake Chad
Persistent drought and
diversion of water has
shrunk the lake to about
a tenth of its former size
• 1972: Larger lake surface
area is visible in this image
• 2001: Impact of drought
displays a shrunken lake,
comparatively much smaller
surface area than in 1972
image
Africa’s Lakes Atlas of Our Changing Environment
Lake Victoria: Falling Water Levels
Concern for Growing Population
Since December 2005, water levels dropped
to alarmingly low levels
Current water levels in Lake Victoria are
below normal and the lowest level since
September 1961
The lake is a crucial resource to some 30
million people
Lake area is the most densely populated
rural region in the world
An estimated 150 000 sq. km. of land have
been affected by soil degradation of which 13
per cent has been severely degraded
Africa’s Lakes Atlas of Our Changing Environment
Population Growth Around
Lake Victoria
• The population growth
around 100 km buffer zone
of the Lake Victoria
• Population growth around
Lake Victoria, East Africa, is
the highest in Africa
• 2010 and 2015=Projected
Africa’s Lakes Atlas of Our Changing Environment
Lake Victoria:
World’s Fastest Growing Rural Area
50.00
Total Human Population Living around Lake Victoria
(millions)
47.23
41.80
40.00
30.51
30.00
22.13
20.00
16.05
11.71
10.00
8.57
0.00
1960
1970
1980
1990
2000
2010
2015
Total Population
Around 1 200 people per sq. km. live in and around the lake; average
annual income is US$ 250 per capita
Africa’s Lakes Atlas of Our Changing Environment
Population Growth:
Lake Victoria vs. Africa
246
250
218
200
159
150
115
100
84
61
50
45
9
12
16
21
26
32
36
0
1960
1970
1980
Lake Victoria
1990
2000
2010
2015
Africa Average
Africa’s Lakes Atlas of Our Changing Environment
Mapping falling water levels of
Lake Victoria
Current
water levels
are below
normal and
the lowest
level since
September,
1961
Source: USDA 2005
Africa’s Lakes Atlas of Our Changing Environment
Lake Victoria: Height Variations
Africa’s
largest
freshwater
lake is now
about a
meter lower
than it was in
the early
1990s
Source: USDA 2006
Africa’s Lakes Atlas of Our Changing Environment
Impact of Invasive Species on Lake
Victoria, Uganda
These images show
water hyacinth infestation
and control of such
invasive species
• 1995: Image shows several
water-hyacinth-choked bays
(yellow arrows)
• 2001: A visible reduction of
Water Hyacinth from many
of the Ugandan bays
Africa’s Lakes Atlas of Our Changing Environment
Lake Kivu: One of Africa’s
“Killer Lakes”
These images show
dramatic changes before
and after the eruption of
Mt. Nyiragongo in 2002
• 2001: Before the January
2002 eruption
• 2003: Shows the track of
the lava flow
Africa’s Lakes Atlas of Our Changing Environment
Toshka Lakes:
Watering the Desert for Farming
These images show the
desert area transformed
into vegetable plots
• 1984-87: Image of the
area before the desert
reclamation project began
in mid-1990s
• 2000: Four new lakes are
visible in this image, faint
blue-green areas around
the lakes are newly created
agricultural lands
Africa’s Lakes Atlas of Our Changing Environment
Toshka Lakes:
Watering the Desert for Farming
2005:
New fields
are clearly
visible in
the image
Africa’s Lakes Atlas of Our Changing Environment
Lesotho Highland Water Project in
South Africa
These images show the
area before and after
construction of Katse
dam
• 1989: Image of the area
before the completion of
the dam in 1995
• 2001: Katse dam created
an enormous reservoir, the
extent of which can clearly
be seen in this image
Africa’s Lakes Atlas of Our Changing Environment
Extensive Deforestation Around
Lake Nakuru in Kenya
These images show the
land cover degradation in
the lake’s catchment
• 1973: The area that hosts
the world’s largest
concentration of flamingos
• 2000: Excision of forest in
the Eastern Mau Forest
Reserve (white lines) will
most likely lead to
disappearance of upper
catchment forest cover
Decline in lake area
from 43 skm to 40
skm in 2000
Africa’s Lakes Atlas of Our Changing Environment
Impact of Challawa Gorge Dam
Nigeria
These images show the
area before and after
construction of the dam
• 1990: Image of the area
before the completion of
the dam in 1993
• 1999: Impact of
flooding upstream from
the dam; colour of the
water in the flooded area
indicates high sediments
Africa’s Lakes Atlas of Our Changing Environment
Severe Flooding Around
Lake Alaotra, Madagascar
These images show
flooding over a wide area
• Flooding destroys
significant portion of crops
• Intensive rice irrigation
occurs at the western part
of the lake (yellow arrows)
Africa’s Lakes Atlas of Our Changing Environment
Impact of Al Wahda reservoir in
Morocco
These images illustrate
the change in land cover
• 1987: The area before
the construction of dams
• 2001: The area after the
construction of large dams
Africa’s Lakes Atlas of Our Changing Environment
Cahora Basa: Mozambique’s Largest
Dam on the Zambezi River
These images show
extraordinary changes in the
Zambezi River system as a
result of the building of
Cahora Basa Dam
• 1972: The Zambezi River
a few years before the dam
construction
• 1999: This image shows
part of the enormous dam
and the lake
Africa’s Lakes Atlas of Our Changing Environment
Invasive Species in Lake Chivero
Zimbabwe
These images show
overall reduction in water
weeds
• 1989: Weeds show up as
green strands along the
edges of the lake
• 2000: This image shows
that water weeds remains a
persistent problem
Africa’s Lakes Atlas of Our Changing Environment
Ecological Changes Around
Lake Ichkeul, Tunisia
These images show the
impact of damming
• 1972: Shows the three
feeder rivers supplying the
lake before they were
dammed
• 2000: Shows the location
of the dams (yellow arrows)
Africa’s Lakes Atlas of Our Changing Environment
Agricultural Expansion Around
Lake Manantali, Mali
These images show the
expansion of irrigated
agriculture
• 1977: Shows the original
meandering nature of the
Bafing River
• 1999: Shows the
expanded irrigated land and
increase in lake water
quantity
Africa’s Lakes Atlas of Our Changing Environment
Lake Sibaya: Wetland of International
Importance in South Africa
These images show
increase in cultivation
around the lake
• 1991: Lakeshore is home
to the only known species
of a rare climbing orchid
• 2001: The yellow arrows
vividly show the increase
of cultivation of marginal
lands around the lake
Africa’s Lakes Atlas of Our Changing Environment
Rapid Shrinking of Lake
Songor Lagoon in Ghana
These images show a
conspicuous reduction in
the surface area, partly
due to intensive salt
production
• 1990: Appears as solid
blue mass of water some
74 sq. km. in size
• 2000: Water area
dramatically reduced to
pale shadow
• Lake is home to fish,
globally threatened turtles
and important bird
populations
Africa’s Lakes Atlas of Our Changing Environment
Changes In and Around
Lake Tonga, Algeria
These images show the
changes brought about
by damming of the
feeder rivers
• 1988: Lake Tonga before
the damming of feeder
rivers
• 2000: Damming
increased irrigation and
drastically reduced the
volume of water entering
the lake
Africa’s Lakes Atlas of Our Changing Environment
Rejuvenation of Djoudj
Sanctuary in Senegal
These images show the
Djoudj Sanctuary before
and after the construction
of the Diama Dam 23
kilometres from the
mouth of the Senegal
River
• 1979: Shows the impact
of drought on the Djoudj
Sanctuary
• 1999: Rejuvenation of the
Sanctuary wetlands due to
significant floods
Africa’s Lakes Atlas of Our Changing Environment
Africa’s Lakes:
Atlas of Our Changing Environment
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