In July 2021, the City of Cape Town and The Nature Conservancy (TNC), signed a two-year Memorandum of Understanding(MOU) which involves a R50 million commitment to clear invasive alien trees in remote mountainous areas to reclaim water losses caused by these trees invading the catchments. The spread of Invasive Alien Plants (IAP) results in reduced groundwater replenishment and streamflow for the Western Cape Water Supply System (WCWSS).
The MOU aims to mitigate the WCWSS estimated losses of over 55 billion liters of water every year as a result of expanding alien plant invasions in the catchments of major dams.
The City is currently funding the operations with grant funding while other avenues are being explored.
‘Research indicates that the restoration of priority sub-catchments through the control of alien plant invasions will result in estimated annual water benefits of 55 billion litres (55 Mm3) or one-sixth of the city’s current supply needs within six years compared to the business as usual scenario. Within 30 years, these yearly gains treble to 100 billion litres (100 Mm3). Catchment restoration provides water at one-tenth the unit cost of various alternative options, making it much more cost-effective than other water augmentation solutions.
‘To sum this up, 55 billion litres is the equivalent of nearly two months of Cape Town’s annual water supply. These losses are severe in a region where each drop of water matters,’ said Mayoral Committee Member for Water and Sanitation, Councillor Zahid Badroodien.
In response to the eradication of alien plant invasions, a network of partners including the City of Cape Town came together under the auspices of the Greater Cape Town Water Fund (GCTWF) Steering Committee.
The focus areas of the GCTWF are:
Priority sub-catchments of the Theewaterskloof, Berg River and Wemmershoek Dams.
Priority sub-catchments of Steenbras Dam.
The Atlantis Aquifer primary recharge zone.
To determine whether large-scale investments in ecological infrastructure restoration are cost-competitive with other supply-side solutions, the GCTWF commissioned studies to assess the effects of nature-based solutions, starting with the targeted removal of alien plant invasions, on water supply.
These partnership operations, during the 2021/2022 financial year created 1 088 (475 women and 317 youth) green job opportunities and cleared 4 617 Hectares in the various catchments. Over 7000 Hectares are planned to be cleared for the current 2022/23 financial year.
‘Climate change is being felt in many parts of South Africa, which means reduced groundwater replenishment and streamflow for the WCWSS and less yield in our dams. Alien plant invasions will continue spreading into our catchments and must be strategically managed to create sustainable sollutions,’ said Councillor Badroodien.
Source: City Of Cape Town