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dam-l Kariba Dam cleared of Hyacinth/LS
Kariba Dam Cleared Of Water Hyacinth
July 26, 1999
Musengwa Kayaya, PANA Correspondent
LUSAKA, Zambia (PANA) - About 2,200 hectares of the water hyacinth on Lake
Kariba has been cleared through aerial sprays with a
chemical weed killer by the Zambezi River Authority, working in conjuction
with other local and international environment control
agencies.
According to the authority's recent report on the weed control measures on
the man-made lake, the aerial sprays with the herbicide,
scientifically known as ''2,4-D'', had achieved an 80 percent success rate
against the ''notorious water hyacinth'' which had covered
almost the entire surface of the lake.
The project had been undertaken in 1998 in two phases, mainly on the
Zimbabwean side, during the months of August and December in an
operation in which the weed was sprayed with a total of 13,000 litres of
the chemical.
The report said only a few patches of the weed both on the Zambian and
Zimbabwean sides were deliberately left. This was because they
were at the time either floating on or close to outlets of water required
for domestic or agricultural use as well as vital tourist points.
Officials concerned have arranged to remove the remaning weed mechanically
or manually.
Laboratory analyses of the water from the lake after the spraying has been
found to contain no trace of chemical contamination, according
to the report.
Officials of the authority Monday told PANA that an international
conference was being arranged for Lusaka in October to plan long-term
monitoring and control measures against the weed on the lake and other
water bodies within the Zambezi River basin, which borders both
with Zambia and Zimbabwe.
The authority has since signed a contract with the Swedish International
Development Agency to investigate the causes of the weed
proliferation in the area. Swedish experts and other stakeholders would,
under the contract, also design and recommend implementation of
a suitable monitoring system of the water hyacinth and other related water
weeds.
Environmental experts said they have identified farming and other
industrial activities within the Zambezi basin catchment area as providing
''the chemical nutrients'' which abet the growth of the weed on the lake
and neighbouring rivers.
Lake Kariba, with a surface area of some 5,580 square km at maximum water
retention levels, is considered as one of the largest
man-made lakes in the world. It was constructed in 1958 on the Zambezi
river to erect hydroelectric generation plants to supply power to
Zambia and Zimbabwe, the two neighbours that now share the dam in half.
It is currently the site of two power plants on either side of the lake.
The Zambian plant generates some 12,000 megawatts of electricity
with about half of the energy being produced by the Zimbawean based utility.
Environment experts have said that the Kariba weed posed both envronmental
and mechanical problems. It is said to inhibit natural
underwater circulation of oxygen necessary for the survival of fish and
other water life.
The weed also poses danger to the operations of electricity generation
turbines by clogging the works and also prevents fishing activities
on the lake.
The Zambezi River Authority, which has its headquarters in Lusaka, was
jointly set up by the two governments in 1987 to be responsible
for the general environmental administration of Lake Kariba and other river
basins within the Zambezi basin.
This site is part of AFRICA NEWS ONLINE.
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Lori Pottinger, Director, Southern Africa Program,
and Editor, World Rivers Review
International Rivers Network
1847 Berkeley Way, Berkeley, California 94703, USA
Tel. (510) 848 1155 Fax (510) 848 1008
http://www.irn.org
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