Gauteng and NW Province

The Vaal River system

The water supply to half of the GNP of South Africa is supported by the Vaal River catchment. The economic and strategic importance of this complex water supply system cannot be over-emphasised. Failure of this crucial water supply will directly demolish the hopes for poverty alleviation for millions in this region, deprive the fiscus of the economic resources required for this throughout South Africa and hold repercussions for the prosperity and prestige of the entire SADC region.

Against this background, the statement by DWA?s Director General regarding supply to Gauteng, which of necessity applies equally to the entire Vaal River and Crocodile West system, was cause for deep concern: “Unless we do something about the current growth trends and needs, we are going to have a water shortage by 2013 … But even with the fastest implementation, these [projects] will only be ready by 2019”. (Engineering News, 26 September 2008). This alone portends a national crisis of the first order.

However, this is to understate the problem. Although seldom stated, overtaking of the system yield by 2013, with no reasonable hope of increasing the resource supply within the next decade, relies on the attainment of a very substantial 15% reduction in demand. To date there is no evidence of any such reduction and year by year the water demands are climbing inexorably along the high demand curve. Put bluntly, this implies that right now we are already living with a 2% supply deficit in the Vaal system. By 2013 we will face a 6% supply deficit, which would rise continually until 2019 when it would reach a staggering 11%. By the time Polihatse Dam (Phase 2 of the Lesotho Highlands Water Project) has warmed up, 86% of its yield would already have been committed, and Mielietuin Dam in the Tugela River catchment would have to be commissioned 3 years later.

Having said that, it needs to be recognised that a water crisis in a complex inter-dependent system is not a binary on/off switch like an energy blackout. It is much slower in developing, like a motor accident viewed in slow motion, or a large ship bearing down on an iceberg, with lots of time to contemplate the approaching collision. Taking account of both the in-stream and off-channel pumped storage and interconnections with distant donor catchments, a critical drought sequence in the Vaal system can take up to 8½ years to reach its end, with progressively more severe water restrictions coming into force as the declining system storage increases the risk of supply failure. This is advantageous since some precious time can be bought to implement emergency measures (such as WDM and WC). However, it also holds inherent risks since decision makers can easily be lured into a false sense of security and leave it too late to react.

Effective management requires decision makers to plan and invest decades in advance, since any new bulk infrastructure requires lead times that stretch longer than the critical drought sequence itself. Hence, even now we are 10 years too late to implement a purely supply side solution. Even if a new dam were to be commissioned during the drought, it would be of little use since dams do not fill during critical droughts. The uncertainties of whether or not we will actually face a severe drought while we remain exposed during the next 10 years can also lure managers into taking unacceptable risks in the hope that they will not occur. This would amount to reckless gambling with the vital interests of the 10 million inhabitants of Gauteng and the many others dependent on the Vaal River system and the prosperity of the nation.

14th SANCIAHS SYMPOSIUM, 21-23 September 2009 CE Herold: The Water Crisis in South Africa

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