Water, Sewage & Effluent May June 2019 - Page 23

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