Lake Chivero chokes with siltation

HARARE - Harare’s biggest water source, Lake Chivero, has been hit by siltation which experts yesterday said was a result of interference with wetlands mainly for agricultural and construction purposes.

The interference with the wetlands has seen the Harare City Council (HCC) losing an estimated $45 million annually due to water loss and subsequent siltation of its main water sources.
Harare has 30 wetlands.

University of Zimbabwe environmental expert Christopher Magadza yesterday revealed that the level of Lake Chivero was now 10 metres higher because of siltation caused by construction and agriculture.

“At the (Lake Chivero) intake tower, the original depth of the lake was 27 metres. When it was surveyed by P Tendaupenyu in 2015, it was only 17m deep.

“The average sediment depth in Lake Chivero is now 4m deep, that is about the height of the internal wall of a suburban house. If not properly managed, Chivero will be completely silted out in the next 42 years,” Magadza warned during a workshop on wetlands in the capital yesterday.

Magadza said apart from siltation, destruction of wetlands was also causing flooding as evidenced in the last rainy season.

“During a rainstorm, much of the downpour is held back by the wetlands vegetation before it reaches the river channel. Consequently, the receiving river receives a modulated run-off from the watershed.

“However, if the wetlands are degraded or replaced with housing and shopping malls, there is nothing to hold back the downpour and it all appears in the river channel in a very short time, causing the river level to rise and overflow beyond its banks,” the biological sciences professor said.

Magadza warned that Lake Chivero will still remain polluted after the rehabilitation of the sewerage works unless wetlands are harnessed to purify run-off which he called the diffuse source pollution.

Chief executive officer of Birdlife Zimbabwe Julia Pierini said officials needed to take the preservation of wetlands seriously if they are to provide adequate water for the city.

She said unless growing concerns of pollution and siltation are addressed, Lake Chivero will not be able to sustain the growing population of Harare.

“Mismanagement of natural resources and not droughts is reducing water supply. While there may be suggestions of artificial wetlands those are most effective for industrial waste like in mines and not for cities,” Pierini said.

Zimbabwe has seven wetlands which are protected under the Ramsar Treaty which the country adopted in 2011.

Comments (1)

Is Dr. Grace aware of this impending danger. I suggest that she be taken on a tour together with her two boys and see for themselves the damage to the lake instead of wasting time taking drugs, partying and beating up people

zano - 25 August 2017

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