Source: Kariba Dam project nears completion – herald
Walter Nyamukondiwa
The US$294 million Kariba Dam Rehabilitation Project, designed to secure the critical and strategic hydro-power infrastructure, is now approximately 94 percent complete, the Zambezi River Authority has said.
In an update, ZRA said rehabilitation work remains on course for completion by the end of the fourth quarter of 2026.
A joint effort by Zimbabwe and Zambia through ZRA seeks to safeguard power generation in a region facing growing demand for reliable electricity generation in the face of ageing infrastructure and systems.
Components of the project include refurbishment of the spillway, targeting restoration of the reliability, safety and functionality of the dam’s six sluice gates, diminished over the last 60 years.
ZRA said natural processes, including concrete expansion and ageing caused by Alkali Aggregate Reaction (AAR), had progressively affected the smooth opening and closing of the gates, prompting the rehabilitation works.
Alkali-Aggregate Reaction is a slow, destructive chemical reaction in concrete between highly alkaline cement paste and certain reactive silica or carbonate minerals in aggregates. This process forms an expansive gel that absorbs water, causing swelling, internal pressure, and eventual cracking and loss of strength.
“The refurbishment was, therefore, intended to restore their full operability and reliability,” said ZRA chief executive Engineer Munyaradzi Munodawafa.
The spillway refurbishment started with Phase 1 in May 2019, which was being implemented by GE Hydro France in association with civil engineering specialists Freyssinet International and is now 99 percent complete.
It involved rehabilitation of the upstream control system for all six sluice gates, including hydro-demolition, concrete repairs, installation of built-in parts as well as rewatering and commissioning of rehabilitated sluices. The remaining works under this phase include commissioning of the gantry crane and site demobilisation. Attention has now largely shifted to Phase Two of the spillway rehabilitation works, which began in August 2024 and has reached approximately 70 percent completion.
The phase is expected to be fully completed by September this year.
Implemented by Morris and Stub Engineers Joint Venture, the second phase focuses primarily on electro-mechanical upgrades involving the design, manufacture and installation of new hoisting systems for all six sluice gates, together with maintenance works on the gates themselves.
The authority said design, manufacturing and delivery of all six hoisting systems were completed in 2025, with on-site installation works commencing in December the same year.
“Currently, the hoisting system installations for sluices number 1, 2, 5 and 6 are in progress,” said Eng Munodawafa.
Beyond the spillway rehabilitation works, the KDRP also includes the now-completed plunge pool reshaping project, which was successfully commissioned in September 2024.
The plunge pool reshaping exercise was regarded as one of the most technically demanding aspects of the rehabilitation programme, involving underwater blasting and excavation works aimed at preventing erosion at the base of the dam wall.
The third component of the rehabilitation programme focuses on institutional strengthening, including enhancing dam safety monitoring systems, technical capacity and governance structures within the Zambezi River Authority.
Funding for the rehabilitation project has been mobilised from cooperating partners, including the African Development Bank, the European Union, the World Bank and the Government of Sweden, with the Governments of Zimbabwe and Zambia providing counterpart funding.
The ZRA said the rehabilitation programme remains critical in mitigating risks associated with uncontrolled water releases that could potentially result in downstream flooding, infrastructure destruction and loss of life.
As part of broader safety measures, the project also includes the development of an Early Warning System designed to improve communication with downstream communities during scheduled or emergency water releases from the Kariba Reservoir.
Hydropower generated from Kariba remains a major driver of industrial activity, economic productivity and social development in the two neighbouring countries.
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