ZRA treads cautiously on Kariba water usage
IN a cautious approach to managing the Zambezi River, the Zambezi River Authority (ZRA) has allocated the lowest amount of water on record for power generation at Lake Kariba in 2024 to the two state-owned utilities of Zimbabwe and Zambia to avoid a potential drastic fall in the dam’s water levels.
Lake Kariba, the world’s largest artificial lake and reservoir by volume, lies along the border between Zambia and Zimbabwe, 200 kilometres downstream of Victoria Falls. The lake is designed to operate between the levels 475,50 metres and 488,50m (with 0,70m freeboard) for hydropower generation.
Following two recent successive droughts, the lake water level is decreasing, closing the review period to December 27, 2023 at 477,12m, just under 11,48 percent usable storage, compared to 475,73m (1,66 percent usable storage) recorded on the same date last year.
Allowing the water level to fall below the recommended level would pose many risks, including a situation that makes it impossible to refill the reservoir for many years, which would impact the lake’s many commercial and recreational functions.
Given that there was a late onset of the rainy season in Zimbabwe, a key part of the Zambezi River’s lower catchment area, ZRA may review its allocations to the power utilities in Zimbabwe and Zambia. It is also important to note the bulk of inflows into the giant lake come from the river’s upper catchment the Barotse Flood Plains in Western Zambia, with inflows into Lake Kariba peaking in the later part of the first quarter of each year.
Kariba Dam supplies 2 010 megawatts (MW) of electricity to parts of both Zambia and Zimbabwe and generates 6 400 gigawatt-hours per annum at full capacity.
Apart from electricity, the lake is of significant tourism value for the two countries, providing beautiful vistas, gorgeous sunsets, excellent fishing and boating options, water sports and fantastic peaceful vacations or weekends spent soaking up the sun.
The 1 050MW Kariba South Power Station is strategically important to Zimbabwe from two perspectives — first, as one of the country’s two largest power generation facilities, and second, the nation’s largest source of the cheapest electricity.
Generally, the level of power tariffs in Zimbabwe is a hybrid of Kariba’s low-cost power and the more expensive thermal electricity generated at Hwange, a 1 520MW facility, whose output is often weighed down by aged equipment
State power utility Zesa Holdings earlier commissioned two 300MW generators to improve power supply in the country, where demand can peak at 2 200MW against reliable capacity of just above or below the peak demand level.
ZRA, which manages the affairs of the Zambezi River on behalf of Zimbabwe and Zambia, said on Thursday it had allocated 16 billion cubic metres (BCM) of water to be shared equally between Zimbabwe’s Kariba Hydro Power Company and Zambia’s ZESCO Limited for their power generation operations at Kariba for 2024.
This will be the least amount of water allocated to the utilities on record. The previous lowest water allocation was 20 BCM in 2016, according to ZRA.
Chief executive Engineer Munyaradzi Munodawafa said: “The 2024 water allocation was informed by the 2023/2024 rainfall forecasts made by the Southern Africa Regional Climate Outlook Forum-27 (SARCOF-27) and the corresponding downscaled projections by the national metrological agencies of Zambia and Zimbabwe.”
Eng Munodawafa said the projections showed a high probability of a normal to below-normal 2023/2024 rainfall season for the Kariba lower catchment area and a normal to above normal rainfall season for the Kariba upper catchment area.
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