Abstracts

An Integrated Watershed Approach to Water Sanitation and Hygiene priorities for Lake Chivero, Zimbabwe

Author(s): Buka, H.; Linhoss, A.; Pote, J.

This paper describes an integrated watershed approach to water sanitation and hygiene for a water supply reservoir near Harare, Zimbabwe`s capital city. From the construction of the lake to the present, considerable difficulties have been experienced in water quality and water treatment. Discharges from urban and rural agriculture, sewage treatment works and industries have caused severe stresses on the lake’s water quality. To combat eutrophication in the mid-1970s, a Hydrobiology Research Unit was established to facilitate pollution research and a biological nutrient removal sewage treatment plant was also installed. This was successful for a decade but afterwards water quality started to deteriorate due to increases in population. The original sewage treatment plants were designed to handle 18 million liters of human waste a day for a population of about 500,000 people but now the estimated population has exceeded 1.4 million people therefore overloading the sewage works. Continued deposition of sewage effluents has contributed to the spread of aquatic weeds such as water hyacinth (Eichhornia crassipes), blue-green algae (Anabaenopsis sp) and spaghetti weed (Hydrocotyle ranunculoides). The weeds strive under a constant supply of nitrogen and phosphorus as they are the major nutrients in the Lake. The area around the lake has been designated as a wildlife sanctuary, which offers the potential for managing water quality better. In 1997 there were recorded fish kills especially the Green headed Tilapia due to low levels of oxygen. A total of 11,735 cholera cases were recorded as of December 2008 due to poor sanitation and water shortages. For these reasons the objective of this review is to assess the integrated impacts of water quality on the environment and sanitation throughout the lake, watershed, and water supply service area.

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