Nairobi,
31 October 2005 – The dramatic and, in some cases damaging
environmental changes sweeping Africa’s lakes are brought
into sharp focus in a new atlas. Produced
by the United Nations Environment Programme (UNEP), the
Atlas of African Lakes compares and contrasts spectacular
satellite images of the past few decades with contemporary
ones.
It was unveiled today at the opening
of the 11th World Lake Conference taking place in Nairobi,
Kenya.
The rapid shrinking of Lake Songor
in Ghana, partly as a result of intensive salt production,
and the extraordinary changes in the Zambezi river system
as a result of the building of the Cabora Basa dam site
beside more familiar images of the near 90 per cent shrinkage
of Lake Chad.
Other impacts, some natural and some
human-made and which can only be truly appreciated from
space, include the extensive deforestation around Lake
Nakuru in Kenya.
Satellite measurements, detailing
the falling water levels of Lake Victoria are also mapped.
Africa’s largest freshwater lake is now about a meter
lower than it was in the early 11000s.
Klaus Toepfer, UNEP’s Executive Director,
said: “I hope these images of Africa’s lakes will galvanize
delegates here at the 11th World Lakes Conference to even
greater action to conserve and restore these crucial water
bodies. Economically lakes are of huge importance. In
the United States, for example, the value of freshwaters
for their recreational value alone is estimated at $37
billion a year”.
“I also hope that the images will
ring a warning around the world that, if we are to overcome
poverty and meet internationally agreed development goals
by 2015, the sustainable management of Africa’s lakes
must be part of the equation. Otherwise we face increasing
tensions and instability as rising populations compete
for life’s most precious of precious resources,” he added.
Mr Toepfer’s concerns are highlighted
in a separate publication, entitled Hydropolitical Vulnerability
and Resilience along International Waters in Africa.
Compiled by UNEP and the University
of Oregon in the United States, it assesses the strength
of legal agreements between countries sharing the Continent’s
major water systems.
The report concludes that, in order
to reduce tensions between nations, much more needs to
be done to beef up shared agreements and treaties to avoid
instability in the future.
It points to the Volta river basin
in West Africa, shared between Benin, Burkina Faso, Cote
D’Ivoire, Ghana, Mali and Togo, as being a particular
source of concern.
Over the next two decades, population
levels are set to double to around 40 million causing
a dramatic demand for water.
Meanwhile rainfall and river flows
in the region have declined steadily in the past 30 years
with this partly linked to higher evaporation rates as
a result of climate change.
“Current water use patterns in the
Volts Basin have already stretched the available resources
almost to their limits and it will be increasingly difficult
to satisfy additional demands,” says the report.
“With the sustainability of the Volta
Basin under threat, there is urgent need for basin states
to cooperate more closely to jointly manage the basin’s
water resources,” it adds.
The precise number of lakes, both
natural and human-made (dams and reservoirs), in Africa
is unknown. But the WORLDLAKE database puts the number
at 677.
Globally there are an estimated 50,000
natural and 7,500 human-made ‘lakes’.
In Africa Uganda, with 69 lakes has
the highest number followed by Kenya, 64; Cameroon, 59;
Tanzania, 49 and Ethiopia, 46.
Gabon, with just eight lakes has the
fewest in Africa, followed by Botswana, 12 and Malawi;
13.
Africa has about 30,000 cubic kilometers of water in its
large lakes making it the largest volume of any Continent
in the world.
The annual freshwater fish catch in
Africa is around 1.4 million tones of which 14 per cent
comes from Egypt.
However the damming of rivers across
the Continent allied to the disposal of untreated sewage
and industrial pollution has reduced the catch particularly
in the Nile Delta and Lake Chad.
Wetlands, often associated with lakes
and river systems, are important for wildlife, water supplies
and filtering of pollutants.
The most important include those in
the Okavango Delta, the Sudd in the Upper Nile, Lake Victoria
and Chad basins and the floodplains and deltas of the
Congo, Niger and Zambezi rivers.
However, many of being drained as
pest control measures or for agriculture. Niger, for example,
has lost more than 80 per cent of its freshwater wetlands
over the past 20 or so years.
Close to 90 per cent of water in Africa
is used in agriculture of which 40 to 60 per cent is lost
to seepage and evaporation, says the Atlas.
Specific Lakes
Lake Songor, a brackish coastal lagoon
in Ghana, emerges as one of the most dramatic visual changes
in the Atlas. The lake in size is home to fish and globally
threatened turtles, like the Olive Ridley and green turtle,
as well as important bird populations.
In December 11000, it shows as a solid
blue mass of water some 74 square kilometers in size.
But by December 2000, the water body is a pale shadow
of its former self.
Intensive salt production and evaporation
at the western end, seen as dark blue and turquoise squares,
is thought to be largely to blame. Agricultural extraction
of water from feeder rivers like the Sege and Zano may
be also taking its toll.
Lake Victoria
The lake, with some 30 million people
living around it, supports one of the densest and one
of poorest populations in the world. Around 1,200 people
per square kilometer live in and around the lake. Average
annual income is less than $250.
An estimated 150,000 square kilometers,
equal to 25,000 football pitches, of land has been affected
by soil degradation of which 13 per cent has been severely
degraded.
The efforts needed to meet the needs
of an additional five million people over the next two
decades will be immense.
The water level of the lake rose in
1998 as a result of the El Nino rains but, over the last
10 years, it has dropped by about a meter according to
measurements by the TOPEX/Poseidon satellite.
Invasive, water hyacinth, has caused
havoc to shipping and the fishing industry. However the
introduction of a pest to control the weed has had some
impact.
Satellite images from 1995 and 2001
show that the green swirls of hyacinth have disappeared
from many of the Ugandan bays like Buka, Gobero, Wazimenya
and Murchison.
Lake Djoudj
Located 60km from St Louis in Senegal,
this lake is a haven for some three million birds such
as Great White Pelicans and the Arabian Bustard. It once
was a series of thin lakes surrounded by streams, ponds
and back waters.
Satellite images underline how the
lake and its surrounding area have been changed dramatically
since the building in 1986 of the Diama Dam 23 kilometers
from the mouth of the Senegal River.
The sheer volume of water available
has now shifted local agriculture from seasonal, flood-based
farming, to year round irrigation-based agriculture.
The atlas highlights other dramatic
changes linked with dams such as the formation of the
Lake Cobora Basa on the Zambezi River after the building
of a barrage in the 1970s.
The atlas links many ecological and other changes that
have occurred since the natural river flow was changed.
These include the decline of flood-dependent grasslands,
the drying out of mangroves and the fall in water levels
on the tributary Shire river which has significantly affected
navigation.
The dramatic loss of vegetation and
deforestation around Lake Nakuru in Kenya is also vividly
seen from space. This may be part of the reason why the
lake, according to UNEP experts, declined in area from
about 43 kilometers to 40 in 2000.
Satellite images of other key African
lakes covered in the atlas include Lake Alaotra in Madagascar;
Lake Bin El Ouidane in Morocco; Lake Ichkeul in Tunisia;
Lake Kariba in Zambia/Zimbabwe; Lake Nyos in Cameroon;
Lake Sibaya in South Africa; Lake St Lucia in South Africa,
Lake Tana in Ethiopia and Lake Tonga in Algeria.
Notes to Editors
The Atlas of African Lakes will be
published in book form in 2006. |