Floodgates to be installed at Corumana

The reservoir behind the Corumana dam, on the Sabie river, in Maputo province, will almost double its capacity by December 2019, according to Mozambique’s Minister of Public Works, Joao Machatine, cited by the independent television station STV. The dam was built with Italian cooperation between 1983 and 1989, but because of the danger posed from attacks by the apartheid-backed rebel movement Renamo, it was never finished. In particular, the floodgates initially planned were never installed – so that when the dam started operating in 1990, the water storage capacity was much lower than expected.

The apartheid war against Mozambique ended in 1992, but the dam was still not completed. But now the World Bank is prepared to finance the installation of the floodgates.

Speaking at a ceremony on Sunday to lay the first stone for the floodgates, Machatine said the government had been negotiating for several years with various partners for funding to complete the dam. The matter became urgent with the crisis in water supply for the Greater Maputo region over the last three years.

The Greater Maputo Metropolitan Area draws most of its water from the reservoir behind the Pequenos Libombos dam, on the Umbeluzi river. The reservoir fell to dangerously low levels in both 2017 and 2018, obliging the authorities to introduce forms of water rationing.

Corumana is an obvious alternative – but only if its storage capacity can be greatly increased. Currently the Corumana reservoir can hold 720 million cubic metres of water. According to Machatine, that will rise to 1.24 billion cubic metres once the floodgates have been installed.

The work is scheduled to take 15 months, and will cost 25 million dollars, financed by the World Bank. The increased water storage will permit an increase in the irrigated area in the Incomati valley from 25,000 to 36,000 hectares, which will allow more food to be produced in Maputo province. Other expected benefits are containing the saline intrusion into the Incomati estuary, and increasing the reliability of the small power station at Corumana, which can generate 16.2 megawatts of electricity. Once the dam is completed, it should be able to pump water to Greater Maputo almost immediately since a 95 kilometre mains pipe has already been installed, running from Corumana to the water distribution centre at Machava, in the city of Matola.