The ManicaPost
Samuel Kadungure Senior Reporter
RUSAPE is on verge of a severe water crisis following Zimbabwe National Water Authority’s unilateral decision to release water from a heavily depleted Rusape Dam to meet irrigation demands in the Lowveld.
Despite objections by the local authority, ZINWA has already started releasing water to meet irrigation demands from Lowveld sugarcane growers.
There is an urgent need to carry out research at various levels to find a solution to the crisis.
It is alarming that Rusape Dam’s capacity to preserve water was this year compromised by ZINWA which released voluminous quantities in anticipation of floods, only for the country to suffer El Nino-induced drought.
Zinwa Save Catchment manager, Engineer Albert Mare, on September 28, advised Rusape Town Council of the decision, saying the council’s abstraction works should be ready to cope with dwindling water levels in the dam.
“Please be advised that ZINWA has started releasing water from Rusape Dam to meet demand from downstream users. You should thus have your abstraction works ready to cope with a drop in water levels in the dam as the town’s 21 months supply will be reserved therein.”
Town secretary, Mr Joshua Maligwa, reacted angrily to ZINWA’s move, arguing that it will affect residents and businesses.
Further drop in water levels will make it impossible for council to lower its pumps which are already operating at maximum head.
“Lowering water levels further will require installing new pumps with a greater head, changing the transformer size and install other ancillary equipment. All the new pumps and transformers are of CAPEX nature, which requires Rusape Town council to do a prior budget and raising $100 000 on short notice cannot be sustainable. Any further releasing of water from Rusape Dam will make our town fail to abstract, treat and supply water to the citizenry of Rusape Town Council,” said Mr Maligwa.
The contentious dam is the only major source of water for Rusape, which has a population exceeding 40 000.
Raw water abstracted from the dam is pumped to Jack Needham Water Treatment Works for onward distribution to users.
RTC abstracts water from the dam through two no electrical-end suction pumps mounted on a trolley lowered down an inclined ramp.
The position of the pumps is dependent on the water levels in order to maintain a predetermined suction head.
The pumps are lowered further down the dam during the dry season when water levels are low and raised during the rainy season when water levels rise.
Currently, the pumps can be lowered to a depth of 30 metres, which is the historical lowest abstraction level.
At present dam level, the pumps are operating at a head of 26m against a designed head of 28m, which means further lowering will reach the head limit and the pumps will not deliver.
Council argues that additional water abstraction will result in the abstract level dropping to 50m during the driest period, which will increase operating head by 20m from 28m to 48m.
“The existing pumps will not be able to operate at this head and will thus not be able to deliver the required water to the WTW.
“Therefore bigger pumps will be required to satisfy the new duty point,” said Mr Maligwa.
