A strategic study of the impact of invasive alien plants in the high rainfall catchments and riparian zones of South Africa on total surface water yield#

The aim of this study was to develop a methodology to determine the impact of upland (non-riparian) invasive alien plants in the high rainfall catchments and riparian areas in all catchments on the total surface water yield available in each of the water management areas of South Africa. This would enable the Department of Water Affairs and Forestry (DWAF) through its public programme Working for Water (WfW) to develop a user charge system for the clearing of invasive alien plants in South Africa. It was found that the total impact of upland invasive alien plants in the high rainfall catchments on the total surface water yield of the country, which included the yield from major dams, minor dams and run-of-river yield, was currently approximately 172 x 106 m3/a and could go up to as much as 1 410 x 106 m3/a in the future. The impact varied greatly between water management areas and had the potential to reach 50 % (195 x 106 m3/a) of registered water use in the Thukela WMA in the future if not controlled. The reduction in yield due to invasive alien plants in the riparian zone in all catchments was estimated to be approximately 523 x 106 m3/a under current conditions and this could increase to 1 314 x 106 m3/a if the riparian zone was allowed to become fully invaded. The combined impact was estimated at 4% of current registered water use and could increase to 16 % of registered water use in the future

Water for sustainable development in the Berg Water Management Area, South Africa

Water is fundamental to human well-being and economic growth. Measuring how water contributes to sustainable development is an important aspect of the United Nations Sustainable Development Goal (SDG) 6, ‘Water and sanitation for all’. This importance is especially significant for water-scarce developing countries such as South Africa. Appropriate indicators can support decision-making and highlight key issues on inequality, unemployment and sustainability. In this paper, additional indicators for SDG 6.4 on water-use efficiency are proposed that focus on how individuals and households benefit, both directly and indirectly, from the allocations and use of water resources. The Berg Water Management Area (WMA) in the southwest corner of South Africa is used as a case study to illustrate the results. Residential per capita water use and municipal water losses were determined for all towns in the area. Figures for jobs and income per unit of water use were calculated for the heavily water-dependent industries, namely, agriculture, agriprocessing, freshwater aquaculture, mining and steel processing. This approach to measuring the socio-economic benefits of water use are relevant for other countries seeking to measure the role that water plays in achieving inclusive sustainable development, and could be included in the final SDG 6 indicator suite