Frequent spells of drought coupled with the uncertainty of municipality water supply are leading South Africans to invest in their own boreholes which requires responsible management.
Boreholes help many people to go off-grid or to supplement the municipal water supply lightening the load on strained municipal water systems. However, groundwater sources being exploited are not infinite.
According to Riona Kruger, geoscientist at SRK Consulting’s Port Elizabeth office, awareness is growing that South Africa is water-scarce and every drop needs to be conserved.
“No longer are farmers the only ones making use of borehole water, but an increasing number of urban dwellers are having boreholes sunk in their yards” she says. “This is a great idea especially where municipalities are battling to supply citizens with enough water to sustain a living.”
She highlights however, that boreholes do add to the pressure on groundwater resources, leading to less water being available for each user. The key is for borehole yields to be professionally assessed and for only a sustainable volume of water to be pumped out.
“The groundwater environment is quite unpredictable, and each aquifer reacts differently to abstraction” says Kruger. “The best way to manage the use of groundwater is to have scientific yield testing done on each borehole, to establish its actual yield capacity.”
This is not usually done by the average groundwater user. Another essential management tool is that every borehole should be subject to regular water level monitoring, irrespective if it is used by a household, a large farm, or an industrial company.
“Boreholes require regular monitoring if their performance is to be reliable and sustainable” she says. “They are also expensive to install and to equip so it makes sense to manage them closely. This means knowing how much water can safely be taken from the borehole and how the abstraction is influencing the water level in the aquifer.”
To monitor changes in the water levels of the borehole, a water level meter can be used manually or installed which automatically records measurements regularly. If these readings are plotted on a graph, it is possible to see whether the volume being pumped is sustainable or whether the level is dropping constantly.
“Should you notice that the water level is declining over time, then you should reduce the volume of the water that you pump from the borehole until the decline has halted” says Kruger. “If the water level remains constant over time, then the yield you are pumping is sustainable.”
She advises that the volume of water than an aquifer can yield over time can change, depending on various factors. The main one is the recharge rate which depends mainly on rainfall levels. The number of new users introduced into the aquifer will also have an impact. Changes in the borehole itself, such as clogging of fractures leading into the borehole, can also affect volumes.
“People often need reminding that while a borehole and its infrastructure may be the property of the owner, the water remains the property of the state. This places the onus on the user to manage the resource responsibly and not to the detriment of others.”
She urges all borehole owners to conserve South Africa’s precious underground water sources by monitoring their boreholes and not over-abstracting water volumes.