Water Demand Projections
The water supply area of the project includes the Lower South Coast Supply
System and the Umzumbe semi-rural areas adjacent to the project. The supply
footprint of the Umzumbe semi-rural area covers the lower Umzumbe area
north-east of the project and is planned to “dove-tail” with Umgeni Waters
Mlhabatshane scheme which will supply the upper Umzumbe rural areas.
Components of the Project
The proposed project will consist of the following components:
An OCS dam on either the Ncwabeni River (site D2) or Gugamela River (site D3A); An abstraction weir on the Mzimkhulu River; An abstraction works with a mechanism to reduce silt abstraction; A pump station and pipeline to deliver water to the dam; and An outlet infrastructure at the dam to make measured releases back to the Mzimkhulu River.
Both alternative dam sites fall under the Nyamande Tribal Authority. Apart from
the tribal lands, a privately owned commercial farm (Gibraltar 8258) is also
situated within the study area, on the southern banks of the Mzimkhulu River. To
date both landowners have been formally notified of the proposed project.
How will the system work?
Additional water yield for the system will be generated by pumping and storing
water from the Mzimkhulu River during high flow months and incremental yield
from the catchment of the OCS dam (relatively small contribution). Water will
then be released during low flow months to augment the supply of water being
abstracted at St Helen’s Rock. No releases will be made directly for the
Ecological Reserve, but by supplying the water demands at St Helen’s Rock, the
flow that would normally be abstracted will contribute to the Reserve.
Upgrade of St Helen's Rock Abstraction Works
The Ugu District Municipality intends to upgrade the existing St Helen’s Rock
Abstraction Works, which will entail the following:
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The construction of a weir across the Mzimkhulu River at St. Helen’s Rock for the following purpose–
To improve the assurance of supply during low flow and drought periods; To allow for the monitoring of the low flows rates; To improve the management, control and economic use of raw water to be released from the proposed Ncwabeni OCS Dam; To prevent salt water from mixing with the drinking water;
Double the peak abstraction rate from 54 Ml/d to 108 Ml/d, in order to meet the
growing demand for water of the Ugu District Municipality. This will require an
increase in the pumping capacity, with alterations and extensions to the
existing pumping station.
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