DAMS, RESERVOIRS & STORAGE
YEAR 2: AN UPDATE ON THE NATSILT PROGRAMME
Executed by the Water Research Commission and funded by the Depar tment of Water and Sanitation, the National Dam Siltation (NatSilt) Programme aims to reduce the risk of siltation in dams. By Lesego Gaegane, senior project manager, NatSilt Programme
T
he programme addresses siltation at the source (catchment area) and identifies pragmatic inter ventions in minimising the transportation and transfer of siltation into the river system, and managing siltation in the sink zone (dam).
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IMIESA July 2022
The NatSilt Programme is implemented over three phases, with the first phase completed in March this year. Phase 1 developed a Dam Operations Model that can be used for the planning and designing of new dams where siltation management inter ventions are incorporated into the design phase of dams. This will allow funds that are made available to design and construct a dam to be utilised further to implement catchment management inter ventions and thus extend the lifespan of the dam. The focus of the model is on improved and sustainable storage capacity of dams, through catchment and engineering inter ventions with a focus on maximising the yield of water resources and their economic benefits. This Dam Operations Model is also used to prioritise siltation management activities and inter ventions on existing
The uMkhomazi River
dams through a cost-benefit analysis. It identifies inter ventions in the three zones – the catchment, the river system and the dam – where users of the model can see which inter ventions are more feasible for implementation. Upstream inter ventions can be more easily justified by making the socio-economic benefits associated with a longer life of a dam quantifiable.
Smithfield Dam Currently, the Dam Operations Model is implemented at three existing dams to improve their storage capacities and enhance their sustainability. It will also be used for a dam earmarked for construction – the Smithfield Dam. Located in the upper uMkhomazi river catchment in the southern part of
