Defining South Africa's Water Source Areas | WWF South Africa

Defining South Africa's Water Source Areas



Posted on 07 November 2013
Defining South Africa's Water Source Areas
© WWF-SA
Water source areas are those areas that supply a disproportionate amount of mean annual runoff to a geographical region of interest. The concept is a relative one, and nested hierarchical areas can be identified as one proceeds from a global scale (e.g. Viviroli et al. 2007), through to continental, regional, national, provincial, municipal and local scales. Strategic water source areas are those that supply substantial downstream economies and urban centres. These water source areas are vital to the national economy.

Strategic water source areas can be regarded as natural "water factories", supporting growth and development needs that are often far away. Deterioration of water quality and quantity in these areas can have a disproportionately large negative effect on the functioning of downstream ecosystems and the overall sustainability of growth and development in the regions they support (Viviroli et al. 2007). Appropriate management of these areas, which often occupy only a small fraction of the land surface area, can greatly support downstream sustainability of water quality and quantity.

In South Africa, such management is particularly important for enhancing downstream water quality and quantity. Not only are the country’s surface water resources extremely limited – South Africa is considered to be one of the driest countries (per capita), with 98 per cent of its surface water already developed (Ashton 2007) – but the country also has a growing water quality problem.

Overloading with nutrients and other pollutants from urban, agricultural and industrial waste has resulted in many dams shifting to an algae-dominated, or eutrophic, state. Sixty-five per cent of the country’s dams are now estimated to be eutrophic or borderline eutrophic (Ashton 2007), with most of these algal blooms containing cyanobacteria (blue-green algae) that is toxic to human health. This renders water of high quality unavailable if not treated, which coupled with failing water infrastructure (Ashton 2007), represents a major challenge to water security in the near future. Water managers are inevitably faced with finding new and innovative ways of improving both water quality and quantity to meet the increasing water demands of the country. Managing strategic water source areas is one way to meet this challenge. 
Defining South Africa's Water Source Areas
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