The aliens have
invaded!
The Berg River Dam is the centrepiece of the Berg
Water Project (BWP) which is designed to capture
the winter rainfall and store it for supply to Cape Town
during the dry summer months.
Alien plants threaten to use up half of the inflows
into two important dams in South Africa.
www.waterafrica.co.za
alien plants on the future water supply
in the catchments of two important
dams.
Dr David Le Maitre, principal researcher
at CSIR.
management would occur in the two
dam catchments over a 45-year period
– the average lifespan of dams built in
South Africa. In each catchment, the
authors base current invasion levels on
Water Sewage & Effluent May/June 2019
21
Alien plants are not indigenous to
South Africa and have been brought
into the country, either intentionally
or unintentionally, and have invaded
natural areas by themselves. The alien
trees typically use more water than our
indigenous trees and plants.
Given their significant use of water
and South Africa’s limited water
resources, it is critical to understand
the impact that not controlling these
plants will have on our water supplies.
This study assumes that no alien plant
Alien invasion
U
p to 50% of the annual inflows
into the Western Cape’s
Berg River Dam catchment
and Limpopo’s De Hoop Dam
catchment could be used up by alien
plants over a period of 45 years, if they
are left uncleared.
This is the warning issued by water
experts Dr David Le Maitre of the CSIR;
Dr James Blignaut of Stellenbosch
University; Professor Lynette Louw,
Professor Tally Palmer and Ian
Preston of Rhodes University. In their
recent paper published by the Water
Research Commission in the Water SA
journal, titled ‘Impact of invasive alien
plants on water provision in selected
catchments’, the authors analyse the
impact of failing to control invasive
innovations
Edited by Tarren Bolton