wellfield testing

More often these days we hear concerns from water users regarding “how much water is the newly drilled borehole of a neighbor extracting from “their” river water”. These are serious question with serious repercussions for sustainable use and economic development. No one wants to lose what they have invested in. On the other hand, from a groundwater perspective, this is very one sided.

In the recent drought of the Cape, Drakenstein Municipality sought to improve its water security and supply through including groundwater into the municipal water supply network. After a desktop assessment of the geology and hydrogeology of the municipal area, it was initially proposed that groundwater development target the Table Mountain Group Aquifer (TMGA), which lies along and within the eastern boundary of the municipal border and is expected to yield 2 - 5 L/s/borehole.

The Western Cape has experienced a drought since 2015 and one of the regions most adversely affected by this drought was the Swartland. Towns in this region make use of water supplied by the Vo?lvlei Dam, which is the Swartland Municipality's bulk and only source of water. Groundwater exploration was undertaken to find alternative sources of water which would be used to relieve some of the pressure on surface water resources. A total of seven towns and communities were identified as high risk and most vulnerable.

A Case study done in the heterogeneous Tygerberg shales underlying the northern section of the Cape flats aquifer. A well field consisting of five boreholes within a 1.6 Ha area was test pumped to determine aquifer parameters and sustainable yields for the well field. The wellfield located in a highly heterogeneous geological setting, proved to be an interesting scenario for wellfield analysis and determination of sustainable borehole yields.