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sources of freshwater supply for the urban areas. Peri-urban
areas often have large open space that are used as dumping
grounds for urban waste, affecting water quality for some cities
(Norström 2007).
HYDROLOGICAL FEATURESOF URBANAREAS
Africa’s urban centres are located in areas of different
topography, climate, physical features and precipitation. These
ecological differences are essential in understanding how
urban areas access freshwater, and how they have become
victims of their own waste.
Some major urban areas such as Johannesburg, Lusaka, Harare
and Nairobi are located on plateaus at over 900 m above sea
level. These cities are located on watersheds with low stream
flows. As these urban areas grew, the need for more reliable and
secure water supply led to their drawing water from reservoirs
downstream, but the flow of waste into the water supply sources
became a problem. As a result some rivers such as the Crocodile
River in South Africa had an increase in mean annual flow due
to wastewater from Johannesburg (Magadza 2003). Some water
bodies supplying these cities have become eutrophic, including
Lake Chivero near Harare and Lake Victoria (Magadza 2003).
Figure 3:
A major challenge with urbanisation in Africa is
the growing population of slum dwellers, who account for 60
percent of Africa’s total urban population. These informal areas
typically lack infrastructure for improved water and sanitation as
well as capacity for garbage collection and disposal.