• Zimbabwe’s 2027 water allowance falls to 11.5 BCM from 18 BCM in 2026

  • Kariba contributes 415 MW, or 26.3%, in ZPC’s website generation snapshot

  • ZRA projects usable storage of 25.1% at December 2026 and 9% at December 2027, increasing pressure on replacement electricity supplies

Harare - The Zambezi River Authority, which manages Kariba Dam on behalf of Zimbabwe and Zambia, has cut the combined water allocation for electricity generation in 2027 by 36.1% to 23 billion cubic metres, according toa latest cicrular.  ZESCO and Zimbabwe Power Company will each receive 11.5 BCM, down from 18 BCM in 2026, following forecasts of strong El Niño conditions, below-normal rainfall and the authority’s internal inflow projections.

The reduction removes 6.5 BCM from Zimbabwe’s annual water allowance and restricts the hydro energy available to an electricity system already carrying a domestic generation shortfall. Lower Kariba output would require additional thermal generation, imported electricity or reduced consumption. The resulting costs would reach the economy through utility procurement, business backup generation and interrupted production.

ZPC’s  snapshot retrieved on 14 October lists Kariba at 415 MW, Hwange’s older units at 473 MW, Hwange Units 7 and 8 at 635 MW, and independent power producers at 54 MW. Combined generation stands at 1,577 MW, with Kariba contributing 26.3%. The display carries no visible timestamp establishing when those readings were recorded.

The  August electricity assessment placed demand at approximately 2,000 MW. Applying that benchmark to the displayed generation produces a domestic gap of about 423 MW before imports, transmission losses and operating reserves. Any reduction in Kariba’s contribution would widen that gap unless other sources increased their dependable output.

A hypothetical 100 MW reduction would increase the gap to approximately 523 MW under the same assumptions. Complete loss of the displayed 415 MW would leave domestic generation at 1,162 MW and a gap of roughly 838 MW. These calculations illustrate the system’s exposure, with ZRA’s statement approving a smaller annual water budget and providing no shutdown instruction.

Kariba’s contribution has also been substantial over sustained operating periods. ZPC-sourced figures published by the Reserve Bank show that the station generated 1,131.41 gigawatt-hours in the fourth quarter of 2025, supplying 38.38% of domestic electricity production. Its output increased by approximately 300 GWh from the preceding quarter.

That additional hydro generation helped absorb weaker thermal production. Combined Hwange output fell from 2,110.04 GWh in the third quarter of 2025 to 1,689.97 GWh in the fourth, a decline of approximately 420 GWh. A tighter Kariba budget would reduce the room available to compensate for thermal outages and maintenance disruptions in the same way.

ZRA’s current-year figures establish that the restriction is forward-looking. The combined 2026 allocation remains at 36 BCM, following an earlier increase from 30 BCM supported by inflows during the 2025/26 rainfall season. Zimbabwe and Zambia retain their respective 18 BCM allowances for this year.

As of 14 October, ZPC had 6.13 BCM remaining under its 2026 allocation. ZESCO had 3.53 BCM remaining, giving the utilities a combined unused allowance of 9.66 BCM. Those balances measure permitted water use for the rest of the year, and their utilisation will influence the reservoir’s starting position for 2027.

Lake Kariba currently holds 23.77 BCM of usable water, equivalent to 36.68% live storage, at a level of 480.65 metres above sea level. ZRA projects usable water of 16.24 BCM, or 25.1% live storage, by 31 December 2026. That would represent a further net reduction of 7.53 BCM from the October reading.

The authority’s 2027 projection is more restrictive. Under its forecast conditions and approved utilisation, Kariba would close December 2027 at 476.80 metres, holding 5.83 BCM of usable water, equivalent to 9% live storage. The projected stock is approximately 64.1% below the usable water expected at the beginning of 2027.

That trajectory means the smaller allocation is itself a conservation measure within a year of expected reservoir drawdown. Generation planning must accommodate the risk that water availability tightens progressively through the dry season. Actual rainfall, inflows and adherence to approved utilisation will determine how closely storage follows the projected path.

ZRA based its decision on the August SARCOF-33 outlook, national meteorological forecasts and its own inflow projections. Its statement expects below-normal rainfall in southern Zambia and much of Zimbabwe early in the season, with drier conditions likely to extend across most areas of both countries from January to March 2027.

The annual allowance constrains electricity production through the volume of water available for turbine releases. ZPC can concentrate generation during high-demand hours and reduce output at other times. Customers could therefore experience tighter supply during particular periods even with Kariba continuing to operate.

Water head, turbine efficiency, maintenance and dispatch schedules determine the electricity produced from each cubic metre. The 36.1% allocation reduction cannot be applied directly to the displayed 415 MW as a generation forecast. Monthly energy budgets would establish the replacement volumes and delivery hours required from other suppliers.

Zimbabwe’s electricity import account already carries substantial expenditure. ZIMSTAT figures previously reported by Equity Axis placed imports at US$84.35 million in the first half of 2026, against US$117 million for the whole of 2025. Additional replacement purchases would increase foreign-currency requirements alongside payment for existing supply commitments.

An illustrative average replacement requirement of 100 MW over a full year amounts to 876 GWh. At an assumed purchase price of US$100 per megawatt-hour, the gross electricity bill would reach US$87.6 million before transmission charges and losses. Actual expenditure would depend on contracted prices, delivery periods and the generation shortfall, with the net additional cost accounting for hydro expenditure displaced.

Zambia’s equal allocation reduction creates overlapping regional procurement exposure. Both utilities could seek additional electricity during periods when regional supplies are restricted. Supplier surpluses, transmission access and payment arrangements would determine the quantity Zimbabwe can secure and the price it pays.

Hwange’s dependable output becomes more consequential under those conditions. Sustained thermal generation would reduce import requirements and preserve Kariba water for critical hours. Breakdowns and extended maintenance outages would increase the burden on procurement and raise the likelihood of customer curtailment where replacement supply falls short.

Businesses would carry the consequences through production losses and expenditure on alternative electricity. Manufacturers can incur restart costs, spoiled material and fewer productive hours. Cold-chain operators, retailers and water-pumping systems require continuing energy, extending the effect into food distribution and household services.

Backup generation protects activity at an additional cost. Fuel, servicing and equipment absorb cash otherwise available for wages, inventory and expansion. Reduced operating hours also spread fixed expenditure across fewer units of output, weakening margins and increasing pressure on selling prices.

Commissioned solar capacity can reduce daytime grid demand and conserve water for later hydro dispatch. Its contribution depends on actual output, grid connections and coordination with Kariba’s operating schedule. Evening supply requires generation or stored energy available during those hours, making delivery profiles important to the replacement plan.

The 2027 supply response will depend on securing electricity before reservoir conditions become restrictive. ZRA says it will monitor utilisation daily, coordinate with utilities through joint technical meetings and assess water availability against its projections. Those reviews will guide subsequent operating decisions as rainfall and inflow evidence develops.

Zimbabwe’s exposure is likely to increase through the dry season if replenishment falls short and new capacity misses commissioning dates. Reliable Hwange production, funded import contracts and coordinated daytime generation would contain the shortfall. Delayed replacement procurement or simultaneous thermal outages would transmit more of the water restriction into power interruptions, higher business costs and lost production.

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