Implications of Converting Lake Kariba to Multipurpose Dam in View of Incresed Demand for Water in Zambia and Zimbabw

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Mwiinga, Chimwaya Pherry
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The Kariba Reservoir is one of the largest man-made lakes in the world. It was created after the impoundment of the Zambezi River at the head of the Kariba Gorge primarily to provide hydro-electric power for mining and industrial development in the then Federation of Rhodesia and Nyasaland (which is now Zambia, Zimbabwe and Malawi). Impoundment started in 1958, filling the lake for the first time in August 1963. Thousands of people and their livestock were displaced as their dwellings and fields got submerged, giving way to the 180.6 km^ Kariba Lake covering over 5,000 km^ of the Zambezi Valley. Paradoxically, extreme poverty and hunger have become endemic among the riparian local communities in Zambia and Zimbabwe.This study looks at the implications of converting the Kariba from a single to a multipurpose reservoir with a view to expand its contribution to meeting Goal Number I of the Millennium Development Goals (MDGs), namely. Eradicate extreme poverty and hunger by 2015. The research involved the collection of extractive water usage data from the Zambezi River riparian interests between Kazungula on the Zambia/Zimbabwe/Botswana tripartite border point and the Kariba Dam, and simulating hydropower generation at Kariba under average hydrologic conditions as well as current and projected installed capacities. The simulation procedure was accomplished with the use of the HEC-3 Reservoir System Analysis for Conservation computer programme. Data collected from the field by way of personal interviews and pumping / usage estimations indicate that an estimated total of 2,540,052 m^day"' (approximately 29 m^/s) is abstracted from the Zambezi River and Lake Kariba between Kazungula and Kariba Dam for non-hydropower usage. This figure comprises abstractions of 165,167 m^day"' on the Zambian side and 2,374,885 m^day' on the Zimbabwean side. For purposes of assessing the impact of extractive water usage on hydropower generation at Kariba Dam in the short to medium term, this study considers an abstraction level of 71 m^/s comprising current usage (as indicated above) and the 2020-25 planned abstraction. The simulation results indicate an insignificant impact on hydro-power generation at Kariba Dam. The study therefore concludes that multiple usage of Lake Kariba does not impinge on its original single-purpose design for hydropower generation at Kariba Dam. In this regard, the study recommends taking full advantage of the extensive Lake Kariba waters to prop up irrigated agriculture in order to contribute to the eventual attainment of MDG Number 1 among the riparian communities and beyond.
Lake Kariba , Water Resources