Author: Dr Anthony Turton - TouchStone Resources
( Article Type: Sustainable Development )
Overview of the Water Situation in South Africa
South Africa has a water-constrained mining-based economy. The water resources have mostly been developed so there is little capacity for new dams.
The national economy is currently transitioning from an extractive phase in which major costs have been externalized, with gold mining as the traditional key component, to a new and as yet ill-defined beneficiation-styled economy centred on a Developmental State. The major challenge of this transition relates to externalities, which are mostly associated with environmental costs that were removed off the balance sheet of strategic sectors such as mining and energy, and are now returning as environmental acidification, and in some cases as increased radiological risk. These externalities are now resurfacing as constraints for new economic development, because they are limiting the quality of the national water resource and driving up treatment costs for the future. The challenge is thus centred on the need to internalize previous externalities in a way that does not further constrain economic development.
Understanding the National Water Resource Challenge
South Africa is physically located between three major weather systems, and the interaction between these generates highly erratic rainfall. To the south we have the Southern Ocean, dominated by the ice sheets of Antarctica and a large ocean mass that generates cold fronts that sweep across the country. This provides winter rainfall to the Western Cape and the coastal regions of the eastern seaboard, and is responsible for the frontal-type rainfall that we receive in other parts of the country on occasion.
To the north we have the Inter-Tropical Convergence Zone (ITCZ) that generates very high levels of rainfall in the Democratic Republic of Congo and Angola. Summer rainfall in the South African hinterland is often associated with a trough of low pressure that feeds in warm moist air from the ITCZ, across the Okavango Delta and Kalahari Desert, dumping it as rain in the Highveld.
The third element is the problematic one, because it interferes with the development of this trough of low pressure that feeds in moist air from the ITCZ. This third element is called the El Niño Southern Oscillation (ENSO), which is driven by sea surface temperatures in the southern Pacific Ocean, which then impacts on rainfall across the southern Atlantic and Indian Oceans as far afield as India and Sri Lanka.
Given the interaction between these three major weather systems, rainfall in South Africa is naturally stochastic, which means that variability is the norm and droughts are common, often punctuated by short periods of localized but intense flooding.
The net result of the three major precipitation variables – the frontal systems off the Southern Ocean, the ITCZ and ENSO – is that river systems are driven by the natural variability of precipitation, and it is here that we need to look in order to better understand the problem. The hydrological cycle moves water around the planet in a constant circulation driven by evaporation and resulting in precipitation. Water is a flux, because it moves in time and space, making it a unique natural resource, unlike oil, which is a stock. A stock is depleted over time, but a flux, if properly managed, can become a sustainable resource.
One critical component of this overall hydrological cycle process is the conversion of rainfall to runoff. Known technically as mean annual precipitation (MAP), rainfall can only become economically useful after the actual event when it becomes water in a river. This is known as mean annual runoff (MAR), and it is the conversion of MAP to MAR that is Africa’s fundamental developmental constraint. The MAP:MAR conversion of Africa as a continent is the lowest in the world at 20%. This means that of all the rainfall across the entire continent on an annual basis, only 20% of this reaches a river and thus becomes useful in an economic development sense. This compares poorly to Australia and Europe that have a MAP:MAR conversion of 35%, South America at 43%, with North America and Asia having a respectable 45% conversion ratio.
These are continental averages so local detail is lost in the aggregation process. In South Africa, the two most important river basins in terms of economic development that they sustain are the Orange and Limpopo systems. Collectively at basin level, the MAP: MAR conversion for both of these systems is a meagre 5.1%, with 94.9% of the rainfall being lost as evaporation shortly after the event. If one homes in closer and looks only at the South African portion of the Orange River basin, then the MAP: MAR conversion is a paltry 3.4%. Seen in this light, our biggest challenge is managing evaporative losses, after we have trapped as much of the stream flow as we are technically capable of with dams.
Assurance of Supply
Our national developmental constraint is the low conversion of MAP to MAR in our major river basins. Stated simplistically, the only way we could develop our economy was by building large dams, because these trap the meagre flows of water in the naturally variable systems and collectively they generate what is known as assurance of supply (AOS). This can be thought of as the guarantee of a given quality and quantity of water as a specific moment in time and space.
Typically our design parameters have been an AOS of around 98%, which means that there is an acceptable risk for a breakdown in supply to happen once every fifty years. In this regard we have literally worked hydraulic miracles, becoming one of the most diversified economies in the world for the type of hydrological regime we live in. One element of this management approach has been the development of many inter-basin transfers (IBT’s), each of which have impacted negatively on the natural pulsing of rivers and thus on the ecological integrity of those system.
Today’s economy in Gauteng Province is 100% dependent on IBT, with a further six of our provinces being dependent for more than 50% of their water flows on IBT.
This makes South Africa exceedingly vulnerable to infrastructure collapse, such as we are currently seeing across the entire country. If we take the above-mentioned example of the Orange River basin once again, where we have a meagre 3.4% conversion of MAP to MAR, we can best understand our national dilemma. Let us call the 3.4% of the rainfall that becomes water in the river 100% of stream flow. Then let us compare that 100% stream flow to the combined storage capacity we have developed in the many large dams found in the system.
In the South African portion of the Orange River basin we have 135 large dams with a combined storage capacity of 271.3% of the MAR. Stated differently, we have almost three times more storage capacity than we have actual water flowing in the river channel in an average year. What this means is that we have developed our major resources as far as we can by trapping stream flow by means of large dams. We are now transitioning to a new phase of hydraulic engineering where for each new dam we build we create larger evaporative areas and thus greater losses.
Stated simplistically, the dam-building era is therefore over. The volume of water that evaporates annually from the Vaal Dam exceeds the natural inflow eleven months of the year. This means that our AOS is now under pressure, and all things being equal by around 2013 the Gauteng region will transition into a situation where the 98% guarantee of water will no longer be possible. It does not mean that we will run out of water – it simply means that there will be times in the future where we have localized breakdowns that will impact on the productive capacity of the economy.
Understanding Water as a Flux
If you think of water as a flux, we can represent that as the infinity symbol shown in Figure 3. We can then superimpose onto that infinity symbol, a four square matrix. Each segment of this matrix represents a specific system related to the management of water resources. The upper left quadrant represents the Ecological System, which consists mostly of water in rivers, wetlands and that flowing across the landscape.
To quantify this portion of the resource we can assign the number of 49,210 million cubic metres (MCM), which is the currently accepted figure. The lower left quadrant then represents the Strategic Storage System; made up of the many large dams we have built as a nation. Here we can quantify the total strategic storage capacity as being 31,567 MCM, which is the foundation of our national AOS. The top right hand quadrant is called the Potable Water System, which consists of the millions of kilometres of pipes that reticulate treated water into our national economy. The lower right quadrant is called the Waste Water System, which consists of the many waste water treatment plants (sewage works) that drain our national economy. With this as a conceptual model we can start to understand that as we approach the absolute limit of our natural rainfall that becomes stream flow (upper left quadrant), we will transition to a future where we have greater reliance on return flows than natural flow.
If managed correctly this will mean that we can continue to have sustained economic growth and development, but it also means that our thinking will have to shift from the building of large dams (lower left quadrant) to the engineering of waste water treatment systems that result in a better quality of return flow emerging from the lower right hand quadrant. It also means that we will have to start thinking of alternatives to dams, with groundwater recharge as a possible viable option. Groundwater recharge stores water in aquifers underground, which means that there are no evaporative losses. This is an exciting technology increasingly being used in places like California and Australia.
Current ChallengesThe single biggest strategic risk to our national economy from a water resource management perspective is the transition from an extractive economy, based largely on gold mining, in which major costs (most notably those associated with environmental and human health impacts) were taken off balance sheet and externalized. In the case of Gauteng as a province, and Johannesburg in particular, this has resulted in massive mine residue areas in which a staggering 410 kilotonnes of uranium waste have been discarded. This waste will now start to impact negatively on water resources across a wide area, given that the residues straddle the continental watershed divide between the Orange and the Limpopo River basins. Uranium is both toxic and radioactive, so these two issues will increasingly start to receive attention in the media as this transition occurs. The challenge to government thus lies in developing policy that enables this transition from an economy in which externalized costs were the norm, to a new as yet ill-defined Developmental State in which those same externalities have now become fundamental constraints. This must all be done against a background of falling technical capacity in the various national science councils , and a growing militancy from a disaffected population that has not yet tasted the fruits of the promised democracy.
Issues of Concern
1) The total MAR of South Africa is 49,210 million cubic metres (MCM) . This is an alarming 4% less than was previously estimated, raising the as yet unknown impact of global climate change as a strategic problem we are not yet on top of. The big question here is the quantification of the risk of global climate change to our national water resource. Will climate change give us more water or less? How will this change our evaporative losses from large dams? How will this impact on processes of eutrophication which are already a limiting factor to our national economy?
2) The total capacity of all dams in the country as at 1 November 2010 was 31,567 MCM. We have limited capacity for new dams given the known evaporative losses, which a recent study by Prof Roland Schultze suggests will increase with a surface water temperature rise by as much as 6°C being anticipated over the next century. To make matters worse, many of these dams are silting up at an alarming pace, so we are losing live storage capacity at an unsustainable rate. It is in this regard that the acid mine drainage (AMD) issue and eutrophication issue must be understood, as these simply reduce the quality of the already dwindling national water resource we have for future economic growth.
3) South Africa has now reached the limit of its readily available water supply and is transitioning into an uncertain future where recycling will become a key element. This means that we need to invest heavily in research and development of processes that will make recycled sewage and industrial water safe for human consumption. In this regard the management of sewage systems will start to emerge as an area of national strategic priority.
4) Water is grossly underpriced. Given that water is a highly politicized commodity, often promised free to potential voters, we now have a situation where insufficient money is being recovered to finance future infrastructure maintenance. Given our high reliance on IBT’s, this can become catastrophic. When seen in light of the AMD issue, many technologies exist, all of which come at a treatment cost of around R9.00 – R12.00 per kilolitre, none of which are economically viable because Rand Water sells bulk treated water at around R3.50 per kilolitre. Stated differently, this artificially low price of water is inhibiting technological development that is needed to improve the quality of the return flows shown at left. This is clearly an undesirable situation, but if left unmanaged, it will become a severe limitation to future development in an increasingly water constrained economy.
ConclusionSouth Africa used to be a world leader in the management of water resources. Sadly we have lost much of the human skills on which that national capacity was based, partly as an unintended consequence of aggressive cadre deployment policies by the government. All things being equal, we are now faced with somewhat of a bleak future in which water resources will increasingly become a constraint to economic development and thus social stability. The situation can be improved , but this will require a policy shift by government, specifically in the areas of cadre deployment and affirmative action quota systems, underpinned by a clear policy statement that water resource management will henceforth be regarded as a national strategic priority. If this is done then we will again mobilize the necessary intellectual capital with which to solve the problems arising from a transition to a recycling economy