A prominent US scientist has added his voice to critics who believe that Mozambique’s floods need not have been so tragic
David Le Page
A leading world authority on dams and the environment has added his voice to criticism of the management of the Kariba and Cahora Bassa dams on the Zambezi river.
Recent flooding of Mozambique has seen flood-plain residents refusing to move; at least 75 people have died.
“Both [Kariba and Cahora Bassa] are not only uni-purpose dams for the generation of electricity, but are operated by authorities who, over the years, jealously guard every drop of water for electricity generation which is why, to date, they have been unwilling to release environmental flows that would attempt to simulate, except during drought years when such flows would not occur, the equivalent of a one- to two-year natural flood,” said Professor Ted Scudder of the California Institute of Technology this week.
Last week Professor Bryan Davies of the University of Cape Town argued that the tragic effects of flooding in Mozambique could be much reduced were the dams to simulate natural seasonal flows and flooding.
Not only would this reaccustom flood plain residents to the danger of regular flooding, but it would lead to substantial benefits for the environment and agriculture.
“Not only do I agree with Professor Davies, but I would even go further in my critique of the way in which Kariba and Cahora Bassa are operated,” said Scudder, one of the commissioners for the World Bank-funded World Commission on Dams.
The commission, which operated from Cape Town for two years before making its final report in December, was chaired by Minister of Education Kader Asmal.
“In addition to the ecological benefits of such environmental flows that Professor Davies mentions, they would also benefit tens of thousands of farm families who practise flood recession agriculture during the dry-season months, graze their animals on the flood plains during the critical months before the commencement of the rains, and catch the fish whose productivity increases with the extent of flooding,” said Scudder.
A Mozambican ecologist, Dr Antonio Hoguane, has calculated that if Cahora Bassa were to reduce the current unnaturally high rate of winter releases, the prawn population around the Zambezi river mouth would be worth an additional $30-million annually.
Both Scudder and Davies are alarmed by Mozambican plans to construct a new dam at Mepanda Uncua.
“On Mepanda Uncua the risk is that its construction will eliminate forever the possibility of environmental flows from Cahora Bassa [at the expense of the delta and downstream users] unless it is operated solely as a run of the river installation, which would be very doubtful,” says Scudder.
One possible reason the Mozambican government is planning the Mepanda Uncua dam is an anachronism of post-colonial history: though in Mozambique, Cahora Bassa continues to be owned and run by the Portuguese government.
The Portuguese are still in debt for the construction of the 25-year-old dam, and would appear to have a greater interest in generating the maximum amount of hydro-electricity than in managing the dam for the benefit of Mozambique.
According to Davies, this pattern of management has prevailed at Cahora Bassa from the moment the dam was completed.
“Even as the dam closed, Portuguese engineers deliberately ignored flow recommendations made by the original impact assessment team, and during the flood season of 1974/1975 they completely stored the annual flood in order to bring the dam on to stream for hydro-power production in the winter of 1975.”
But the Portuguese seem to have allies in the South African Department of Water Affairs and Forestry, which last week essentially dismissed Davies’s arguments. It said: “It is unhelpful for South African environmentalists to expect Mozambican authorities to conduct ecological experiments at the expense of their national economy to which the power from the dam makes a substantial contribution.”
This response appears to be at odds with the department’s own mandate. South Africa’s own three-year-old Water Act stipulates very similar management for South African dams and rivers to that suggested by Davies, Scudder and others for the Zambezi.
The Water Act provides for environmental assessments of normal seasonal flows and flooding frequency for particular rivers. Once these assessments have been made, dam managers will be obliged to gauge water releases to mimic the natural flow of rivers.
These assessments of the “ecological reserve” have not yet been completed for most South African rivers. But it is expected that in five years most South African water courses will be managed according to such regimes. Similar programmes, with the help of South African scientists, are being developed for river management in Australia.
Davies and United States colleagues Richard Beilfuss, a wetland hydrologist for the International Crane Foundation, and Lori Pottinger of the International Rivers Network, are puzzled and disturbed by the response from the department in answer to questions posed by the Mail & Guardian.
“The recent press release by the department on the relationship between large dams on the Zambezi and the present Mozambique floods strikes us as written to cast doubt on growing criticism from the scientific community of the operation of dams along the Zambezi and perhaps also to personally discredit those of us who have been vocal critics of the present catastrophic flooding in Central Mozambique,” wrote Davies, Beilfuss and Pottinger this week.
“The department press release notes that dams ‘can help reduce the impact of floods’. We vehemently challenge this myth; the myth at the hub of the present problem facing the inhabitants of the Zambezi and the authorities and aid agencies involved in rescue operations … the dams cannot hold back the really big floods that come along every 10 to 20 years. The result? A predictable disaster.”