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 FEATURES OF URBAN AREAS
Africa’s urban centres are located in areas of different topography, climate, physical features and precipitation. These
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.
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).
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