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The delivery of safe drinkingwater inmost of the basin’s urban areas is hindered by old and inadequate infrastructure.
Some wetlands in the Zambezi River Basin
are receding due to reduced flows caused by
droughts and water extraction. Other wetlands
are increasingly being infested by aquatic weeds
while still others are exposed to persistent
organic pollutants such as DDT, the pesticide
dichlorodiphenyltrichloroethane. Some wetlands
have also been inundated with water as a result
of dam construction. Additional threats to
wetlands include overexploitation of resources,
uncontrolled fires, pollution and deforestation.
These threats alter wetlands, causing habitat
change and species loss (Chenje 2000).
The Lower Shire River in Malawi, the Zambezi
Delta in Mozambique, the Kwando/Linyanti/
Chobe system draining down the Caprivi in
Namibia, and the Kafue flood plains in Zambia
are the most environmentally sensitive wetlands
in the basin (Bethune 1999).
The Kafue Flats
The Kafue Flats in southern Zambia are an
extensive floodplain system that lies in the
middle Kafue River. The floodplain covers an area
of approximately 6 500 sq km, and is sandwiched
between two large dams, which are 270 km
apart (Mumba and Thompson 2005). The dams
have altered the hydrological regime of the
system, with backwater from the Kafue Gorge
Dam downstream and releases from the Itezhi-
Tezhi Dam upstream creating a permanently
flooded area in the floodplain. The hydrological
and vegetation changes have affected the
habitat for important wildlife communities
including the endemic lechwe antelope, (
Kobus
lechwe kafuensis
). The other dramatic change
in vegetation is the colonization of parts of the
floodplain by the invasive alien plant,
Mimosa
pigra
(Mumba and Thompson 2005).
The Kafue River and its floodplains are heavily
utilized and highly industrialized, and subjected
to pollution from mining, industry, agriculture
and municipalities. A joint study by the
University of Zambia and the Swedish Lulea
University of Technology shows high levels of
heavy metals, particularly copper, in the Kafue
River near the Copperbelt area. The floodplain
also suffers from heavy grazing and overfishing
(SADC and SARDC 2008).
The Zambezi Delta
Water regulation from Cahora Bassa dam has
substantially reduced the Zambezi Delta wetland
productivity and even offshore shrimp catches in
Mozambique (Chenje 2000). Saltwater intrusion
has become a problem in the delta as a result of
reduced freshwater flows and the lack of regular
substantial seasonal floods. Irregular floods in the
delta are associated with cyclonic rainfall along
the Mozambique coast.
Wetlands
© R. J. Boroto