Although South Africa’s current dam infrastructure setup is reliable, sustainable consulting in the built and natural environment provider WSP Africa Structures senior engineer Peter Townshend says there are a number of short- and long-term solutions that South Africa can pursue to augment water supply to meet increasing demand.
“Because the country is experiencing a growing demand for water supply, more pressure is now being put on this infrastructure which the population growth far exceeds.”
This necessitates supplementing current water supply, which would require more dams. He commiserates, however, that almost 95% of water resources in the country have been allocated, leaving few opportunities to build new dams.
Moreover, while Townshend notes that government is aware of water supply problems, the allocation of adequate funds to redress it, which are currently not available, is required.
He notes that this is further compounded by the country’s predilection to react to crises, rather than being proactive in water management. “This is reflected in the dire situation in the Western Cape, with the average capacity of dams [being] 14% – at critical level – resulting in level-four water restrictions having been implemented.”
Townshend says one of the ways to address water supply issues is to raise the level of the walls of existing dams higher, which will lead to an increase in storage levels.
This measure will also offset the losses that occur from sediment that gets carried down and deposited into dams; this silting has resulted in the country losing a large proportion of total dam capacity, estimated at 20%, to sediment, he explains.
Reusing effluent water by intensively treating it to meet drinking water standards is another option, he notes. While this may sound unappealing, it is being done in other countries and might have to be considered “very seriously” in the imminent future, he states.
Further, the municipalities of Cape Town and Port Elizabeth are considering desalination, and “while this is an assured source of water for coastal areas, it is costly,” says Townshend.
He says, in dry areas, especially in the Karoo, there are flash floods that should be capitalised on through actively recharging groundwater (a hydrologic process where water moves downward from surface water to groundwater), subsequently allowing for water to be extracted later.
Another option is the expensive transferring of water, for example, from an area where there is better water supply with big rivers, such as the Zambezi.
Townshend highlights that one of the short-term goals to ensure adequate water supply is making the public aware that water is a precious commodity. “Not saving water, unlike with other commodities, such as electricity, is life threatening.”
WSP conducts awareness campaigns on the need to use water more prudently every year during Water Week, and the momentum is leveraged to continue throughout the year. Townshend extolls that this has led to people using water more sparingly.
Reducing water losses by municipalities, currently estimated at between 35% and 40%, is another priority. This is water that cannot be accounted for, lost to either leaking pipes or valves and uncontrolled withdrawals. “If we can get on top of these losses, it will be a huge improvement for water supply,” he enthuses.
Townshend emphasises that rainwater harvesting should gain prominence. This can be accomplished through rainwater tank installations on private properties and incorporation of these into the building designs of businesses.
WSP enables this through green buildings, which are environmentally designed for energy efficiency, as well as for water capture and reuse.
He refers to the example of the many houses that are now being equipped with solar heaters following government initiatives, the precedent of which he believes should be applied to the water industry through initiatives to equip houses with rainwater tanks.
Townshend avers that, when Gauteng was experiencing a drought and subsequent water shortages several months ago, with dam levels decreasing to about 30%, this would have been the time to implement such measures.
However, he laments the public’s short memory span, as the area was fortunate to recover swiftly with heavy rainfall depositing a large amount of water in the upper catchment area of the Vaal dam and filling it up quickly. “This led to apathy for saving and managing water.” He warns against this, as scientists have noted that the country is water stressed; therefore, this state of apparent water security is a “false dawn”.
He also acknowledges the option of water tariffs, which can work, but are often not well received, and are difficult to implement and regulate.
Townshend expounds that government and the private sector have started to treat acid mine drainage water, which will supplement water supply. “This is a short-term solution, as it modifies water to only raw standards, not drinking quality.”
Townshend reiterates the importance of remembering that water is a scarce commodity.
“We must not have short memories. Although we were fortunate to avert a water crisis in most of the country, as a population, we must be aware of water-saving devices and the reuse of water wherever possible,” he concludes.