Making the most of a crazy dam

2nd May 2014

By: Mark Botha

In our current infrastructure orgy, politics has trumped sense again. Last month, President Jacob Zuma officiated at a function to mark the start of construction of a sizeable dam on the Tsitsa tributary of the uMzimvubu river, the largest in the Eastern Cape.

Many Engineering News readers will, naturally, be delighted. Can we think through how to maximise the possible positive social and environmental outcomes from this misadventure of capital and patrimony?

Leaving aside the environmental costs of dams (which have to be weighed carefully against benefits), there are puzzling questions about the Ntabelanga dam.

What is it to be used for?
It cannot provide water to any urban centre or other user group that can afford it.

There is precious little land for irrigation around it, even if expensive and energy-inten- sive pumps are installed to shift the water further afield. Further, the social acceptability of new irrigation schemes and the land econo- mies they require for viability are in serious doubt.

Ntabelanga is not a hydropower dam (that is being planned for 20 km downstream in a far better location, and Eskom must be happy that a good chunk of the Tsitsa’s sediment will be trapped before reaching its turbines), although that might have been useful.

What’s more, it is not really useful as a regional domestic water supply system. That could be done far more cheaply by building smaller distributed solutions or fixing the massive backlog in the repair and maintenance of existing water schemes in the region.

But, if we are going to have the dam any- way, can we at least ensure that it costs as little as possible (unlike the De Hoop dam debacle in Limpopo)? Estimates vary, but a figure of R20-billion has been floated for the Ntabelanga dam and regional distribution network. Will the National Treasury stump up the cash, as well as second some astute auditors to ensure no unnecessary overrun and cost escalations that dog these types of projects?

Perhaps more important, how do we maxi- mise the social and environmental returns from the multibillion-rand investment? What could be done to pursue these oft-neglected imperatives in infrastructure projects?

We could consider a significant investment in fixing and maintaining the ecological infrastructure of the catchment by rolling out large-scale soil protection, rehabilitation and anti-erosion works. This is not only for sound soil and resource conservation reasons, but must also make a useful contribution to extending the life of a reservoir and associated machinery in one of South Africa’s most erodible (and eroding) catchments. We have some inkling of how to do this, but a decided lack of focus and scale – the very things that an infrastructure project can bring in spades.

Locally appropriate, culture- and land-use- sensitive measures to trap soil and sediment before they leave the fields and rangelands of the catchment must be a cheap investment in dam longevity and return on capital. They also have the added benefits of improving soil fertility and water-holding capacity, improving forage and animal condition, increasing dry-season flows for communities using rivers directly as water sources, and reducing floods that damage bridges and water infrastructure. It is also a direct investment in useful economic activity in the catchment.

Further, one could use some green-economy- type thinking to assess dam design and construction options. Is this the best approach to deal with the pressing water service issues in the region? Are there parallel objectives that could be met by sensible design and marginal additional costs? It is difficult to build any significant hydropower into a dam to be used for storage or water supply, but, perhaps, we could use the dam as part of a pumped-storage scheme to maximise use of the burgeoning wind and solar energy projects The planning and site selection reports for the dam did not really exhaust the alternatives or clarify the ultimate rationale for the dam. Could sound catchment rehabilitation perhaps result in a slightly smaller, cheaper dam being possible?

Are there more labour-intensive means of construction than pouring vast amounts of concrete across a river? Dam safety is paramount, but have all aspects of involving local labour pools in construction, maintenance and site de-establishment been exhausted?

As a pragmatist, one needs to accept that a raft of large, expensive infrastructure will be built – whether useful, needed or not. But if we are going to mortgage our future for them, let us at least ensure we get the best long-term outcomes across a range of laudable social objectives.


Botha is an independent strategist on environmental and biodiversity issues -