Groundwater in pursuit of achieving the Sustainable Development Goal 6.4

One of the abstraction pumps at the Theewaterskloof dam in 2018 as a result of three years of below average rainfall.

We know that climate change will, and is already, impacting the hydrogeological cycle. Although the longer term (50 to 100 year) predictions remain unclear, with future models suggesting both a drier and a wetter Western Cape, what is clear is that that mean annual rainfall has become less over the last three decades, and this is well depicted in the three multiyear graphs showing Hermanus (South Coast), Cape Town Airport (Cape Peninsula) and the town of Atlantis (West Coast). Also noted, but not shown in the graphs, is that the frequency of rainfall events has decreased (less rain days measured). The decreased frequency is also resulting in more intense and episodic rainstorms when rainfall does fall. Exacerbating the problem, the rising temperature of the Western Cape causes a consequential increase in evaporation and evapotranspiration which is a contributing factor to net water storage in our dams. On the backdrop of climate change impacts we have the additional responsibility of the burgeoning population of the Western Cape, with an inward migration placing demands on water resources. While it is exceedingly unlikely that future dam construction is feasible, the challenge is therefore that water planning, security and sustainability in the Western Cape, and South Africa as a whole, until now unduly reliant on surface water storage, needs to look for new solutions to solve the dilemma.

17-year average annual rainfall taken from a range of weather stations across Hermanus, as well as the South African Weather Services weather station in Atlantis and at the Cape Town International Airport, in the Western Cape of South Africa. The linear trend for all sites shows a decrease in rainfall over the past 17 years.
17-year average annual rainfall taken from a range of weather stations across Hermanus, as well as the South African Weather Services weather station in Atlantis and at the Cape Town International Airport, in the Western Cape of South Africa. The linear trend for all sites shows a decrease in rainfall over the past 17 years.

Sustainable Development Goal 6.4

In the face of a changing climate, our reliance on these sources of water will be insufficient to meet the Sustainable Development Goal (SDG) 6.4 – “Water Use and Scarcity”. SDG 6.4 states that “By 2030, substantially increase water-use efficiency across all sectors and ensure sustainable withdrawals and supply of freshwater to address water scarcity and substantially reduce the number of people suffering from water scarcity”. To this extent, Umvoto Africa has been working closely with the City of Cape Town, and the Overstrand municipality to achieve sustainable usage of water resources, by combining sustainably managed groundwater resources to their water use supply systems.

By incorporating groundwater into the supply, the City of Cape Town and the Overstrand Municipality can better manage their supplies of water, and essentially use groundwater as a giant underground reservoir for the storage of water through Managed Aquifer Recharge. Groundwater is also less susceptible to evapotranspiration, and groundwater levels can be accurately monitored to avoid over-abstraction and allow for recharge, either naturally or through Managed Aquifer Recharge.

One of the abstraction pumps at the Theewaterskloof dam in 2018 as a result of three years of below average rainfall.
One of the abstraction pumps at the Theewaterskloof dam in 2018 as a result of three years of below average rainfall.

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