The Zambezi River Authority, which manages Lake Kariba on behalf of Zambia and Zimbabwe, has allocated 13.5 billion cubic metres of water to ZESCO, Zambia's state utility, for power generation at the Kariba North Bank station in 2025. That compares with 8 billion cubic metres in 2024, according to reports in the Zambian press in early March. The higher allocation should allow more generation, but it follows one of the worst years for hydropower in the region's recent history.
Through 2024, a severe drought across southern Africa, linked in part to the El Niño event, cut inflows into Lake Kariba to very low levels. With less water allowed through the turbines, Zambia faced daily power cuts that the BBC and other outlets reported reaching 21 hours a day in some areas by the second half of the year. Zimbabwe, which draws on the same lake for the Kariba South station, also faced extended outages.
Why Kariba matters so much
Lake Kariba is one of the largest man-made reservoirs in the world by volume, formed by the Kariba Dam on the Zambezi. Hydropower supplies the large majority of Zambia's electricity, and the Kariba North Bank station, together with the Kafue Gorge complex and other plants, makes up most of the country's installed capacity. Zimbabwe relies on a mix of Kariba South and coal-fired plants at Hwange.
That dependence means rainfall in the Zambezi catchment translates directly into the power supply. In a normal year, the rainy season from November to April refills the lake, and the authority sets annual water allocations to the two utilities based on expected inflows and the need to keep the reservoir above its minimum operating level. In a drought year, the allocation is cut to protect the dam's ability to generate in future years.
The 2024 shock
The 2024 allocation of 8 billion cubic metres was well below normal levels, and ZESCO had to manage generation within that limit for the full year. The Guardian reported in November 2024 that water levels at Kariba were close to the minimum operating level, and that both countries were importing power where they could and turning to emergency generation.
Zambia's economy felt the effects across sectors. Copper mining, the country's main export industry, depends on reliable electricity, and mines with long-term supply contracts faced curtailment or turned to imports and on-site generation. Small businesses reliant on grid power for refrigeration, milling and manufacturing reported heavy losses. Households turned to charcoal and diesel generators.
What the 2025 allocation changes
The increase to 13.5 billion cubic metres reflects better rainfall in the 2024 to 2025 wet season. ZESCO has indicated that the higher allocation will allow it to increase generation at Kariba North Bank and reduce the length of daily load shedding. The utility has signalled that supply will remain constrained by water availability through the year.
The allocation does not restore the lake to comfortable levels. Reservoir levels are a function of several years of inflows, and one average or slightly above-average rainy season after a severe drought does not fully refill a reservoir of Kariba's size. The authority's approach is likely to remain cautious, setting allocations that preserve storage in case the next season is also dry.
Regional power trade
The Southern African Power Pool allows Zambia and Zimbabwe to import electricity from neighbours, including Mozambique, South Africa and Namibia, subject to transmission capacity and the availability of surplus power. In 2024, imports helped close part of the gap, but they were expensive and limited. South Africa's own supply improved during 2024 after years of load shedding, which made some additional exports possible.
Mozambique's Cahora Bassa hydropower station, downstream on the Zambezi, is also affected by the river's flow, which means regional drought can reduce output across several hydro plants at once. That correlation limits the extent to which regional trade can offset a dry year.
Diversification efforts
Zambia's government has announced plans to diversify its power supply away from heavy reliance on hydropower. These include solar projects, some developed with private investors under power purchase agreements, and expanded use of thermal generation. Solar generation in Zambia is strongest during the dry season, when hydro is most constrained, which makes it a natural complement. Battery storage would be needed to shift solar output into evening peaks.
Zimbabwe has also pursued additional coal capacity at Hwange, where new units have been commissioned in recent years, and has opened the door to private solar projects. Both countries face financing constraints, and debt restructuring processes in Zambia have affected the cost and availability of finance for new projects.
What it means for energy markets
For international energy markets, the Kariba drought is a regional story with two wider implications. The first concerns copper. Zambia is one of Africa's largest copper producers, and copper demand is closely tied to electrification and grid investment worldwide. Power constraints at Zambian mines can affect output at the margin, and investors in Zambian mining projects now factor power supply risk more explicitly into project plans, including on-site solar and long-term import contracts.
The second concerns hydropower planning more broadly. Hydropower provides a large share of electricity in many African countries, including Ethiopia, the Democratic Republic of Congo, Mozambique, Uganda and Malawi. The 2024 drought illustrated how a single bad year can turn a low-cost, low-emission power system into a crisis. Lenders, insurers and planners are increasingly asking for hydrological stress tests that model multi-year droughts, rather than relying on long-term average flows that may not reflect the current climate.
What to watch
The main variable for the rest of 2025 is rainfall in the 2025 to 2026 wet season, which begins in November. If that season is normal or wet, the lake should continue to recover and allocations for 2026 could rise further. If it is dry, the authority may again have to restrict generation.
In the meantime, indicators to follow include Kariba's weekly lake level reports published by the Zambezi River Authority, ZESCO's load-shedding schedules, and progress on solar projects that have reached financial close. The pace at which new solar capacity comes online will determine how much protection the system has against the next dry year.