It is a trend that requires responsible management, warns SRK Consulting.
While boreholes do help many people to either go off-grid or supplement municipal water supply, thereby lightening the load on strained municipal water systems, the groundwater sources being exploited are not infinite. According to Riona Kruger, principal geoscientist in 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,” said Kruger. “This is a great idea, especially where municipalities are battling to supply citizens with enough water to sustain a living.”
She highlighted, 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 mostly quite unpredictable, and each aquifer reacts differently to abstraction,” she said. “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 often not usually done by the average groundwater user, she notes. 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 need regular monitoring if their performance is to be reliable and sustainable,” she says. “They are also expensive to install and 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 level of the borehole, a water level meter can be used manually or installed (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 water that you pump from the borehole until the decline is halted,” said Kruger. “If the water level remains constant over time, then the yield you are pumping is sustainable.”
She advised that the volume of water that 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 the borehole and its infrastructure may be the property of the owner, the water remains the property of the state,” she said. “This places the onus on the user to manage the resource responsibility and not to the detriment of others.”
She urged all borehole owners to conserve South Africa’s precious underground water sources by monitoring their boreholes and not over-abstracting water volumes.