THE City of Harare is losing close to 20 percent of its water storage capacity which translates to $45 million in potential revenue at Lake Chivero as a result of interference with wetlands, a University of Zimbabwe Lecturer has revealed.
Professor Chris Magadza of the Department of Biological Sciences at the University of Zimbabwe said the abuse of wetlands had led to siltation which had led to the reduction in the depth of the lake.
He was addressing a Journalists Wetland Information workshop organized by the Harare Wetlands Trust.
He said at the intake tower the depth of the lake had reduced from the original 27 metres to just 17 metres, leaving the average sediment depth at Lake Chivero at just four metres deep, the equivalent of an internal wall of a house.
“The total loss in storage capacity is 41 400 mega litres that is close to 20 percent of its design storage capacity. At a tariff rate of $0.8 per cubic metre this translates to an annual revenue loss of $45 million arising from interfering with wetlands functions, one of which is sediment interception,” he said.
Magadza said rivers fed by Harare’s wetlands had become an important feature in the City of Harare’s water security, noting that close to 50 percent of the city’s tap water was recycled.
Julia Pierrini of the Harare Wetlands Trust said they were now lobbying to have all the wetlands in Harare declared Ramsar sites, which will make them internationally protected sites under the Ramsar International Convention on Wetlands agreed to in 1971.
“What we want now is for the whole of Harare to be declared a Ramsor site, because it is a wetland city which was built in the middle of where the streams begin in the Upper Manyame Catchment base,” she said.
She said almost all of Harare’s wetlands were under threat as a result of illegal construction of housing and commercial units and urban farming activities.
The city of Harare, she said, was now largely dependent on underground water; hence the more important it was to preserve its wetlands.
Currently there are seven water sources in Zimbabwe that have been declared Ramsar sites, among them the mighty Victoria Falls, Lake Chivero and Monavale.
Although Zimbabwe signed the Ramsar Convention in 2013, it has not been domesticated.Advertisement
Wetlands face a number of threats including pollution, illegal logging and encroachment from construction projects.
Wetlands are said to be the most biologically diverse ecosystems on earth and act as giant sponges, soaking up rainfall and slowly releasing it over time.
They also serve as natural sewage treatment works, absorbing chemicals, filtering pollutants and sediments, breaking down suspended solids and neutralizing harmful bacteria.