South Africa is a water-stressed semi-arid country with limited yearly rainfall supply and a lack of perennial streams, which, together with future population growth and the uncertainty brought on by climate change are likely to have significant financial, human and ecological impacts on already scarce water resources, says industrial wastewater management company Talbot & Talbot.
Much of South Africa’s water supply originates from groundwater sources. These are geographically widespread and almost two-thirds of South Africa’s population depend on them for their domestic water needs, states the Department of Water Affairs (DWA).
Globally, groundwater is an essential freshwater resource for both socioeconomic and environmental systems, and forms a critical buffer during periods of drought. This makes the protection of groundwater supplies – through management, pollution control and remediation – essential.
In developing countries groundwater management is generally neither strongly emphasised in national water legislation, nor implemented where role- players are aware it is necessary.
Groundwater is water that exists in the pore spaces and fractures in rock and sediment beneath the earth’s surface. It is naturally replenished by surface water from precipitation or snow and then moves through the soil into the groundwater system where it recharges the water table.
Groundwater sources are generally extracted through the construction and operation of extraction wells or boreholes. In areas where rural infrastructure is minimal, rural communities will often rely on more informal, traditionally developed groundwater sources such as hand-dug wells, springs and sand abstraction.
Currently, South Africa’s groundwater resources supply about 15% of the total volume of water consumed nationally. Of this, almost 64% is used for agricultural irrigation purposes, while exploitation for mining and domestic consumption constitutes 8%, says the DWA.
“Despite our reliance on groundwater, it has remained a poorly understood and managed resource, most likely due to its hidden nature and the lack of adequate knowledge and physical data pertaining to aquifer characteristics and behaviour such as recharge, discharge, base flow and aquifer-dependent ecosystems,” Talbot & Talbot says.
Most groundwater quality and quantity problems in South Africa are related to human activities that result in infiltration of chemicals and toxins used in industry, acidification and increased metal content in mining, salinisation and eutrophication, microbial effects in urban development, as well as the intensification of agricultural practices such as sedimentation, infiltration of agrochemicals and salinisation through irrigation return flows.
Deteriorating standards in wastewater treatment, agricultural drainage, land-use patterns and waste disposal intensify the problem. Contaminants either seep through the soil to reach the water, are washed into the ground by rainfall or surface run-off, or leach from contaminated landfills and other buried hazardous wastes, all of which affect both human wellbeing and ecosystem functioning.
Millions are spent every year on control and remediation measures even though remediation is difficult and extremely costly. Remediation of soil and groundwater is usually carried out by government agencies, or environmental companies, with the first step being the identification of the contaminants.
The analysis and classification of the pollutant is critical in that it enables identification of appropriate solutions for remediation. Analyses are performed by internationally recognised environmental laboratories that can provide expert interpretative data to consultants who are then able to make recommendations on and implement remediation measures.
Reliable data is vital for making informed decisions. Once identified, the contaminant is either physically removed to a landfill site or subjected to chemical oxidation methods, which remove the pollutant from the soil before it is reintroduced back into the environment. Specialised mechanical techniques in the form of pump-and-treat methods are used, or the area is rehabilitated in situ with the use of microorganisms.
“Although groundwater is a vital source of water for many and has given rise to several short- and medium-term socioeconomic benefits, the additional pressure on the resource has put many aquifers at risk owing to high extraction rates. “Until 1998, groundwater was considered a privately owned asset, under the traditional riparian system.
“However, after the promulgation of the National Water Act, No 36 of 1998, groundwater was declared a public resource with shared entitlements to use; therefore, exposing the resource to further exploitation,” Talbot & Talbot states.
Although provision was made for the management of groundwater resources, under the DWA, the motivations behind the regulations and guidelines have been difficult to account for and implement on a regional level and, subsequently, are largely overlooked or neglected, says Institute of Environmental Systems Research Kathrin Knüppe in her scholarly article titled ‘The challenges facing sustainable and adaptive groundwater management in South Africa’, published in 2010.
Therefore, there are still many challenges to overcome to achieve the sustainable management, appropriate allocation and effective protection of South Africa’s groundwater resources.
Talbot & Talbot says perhaps the most significant challenge is education and awareness, and collaboration among stake- holders on the importance of the sustainable and efficient use and monitoring of groundwater.
Greater awareness and under- standing, as a first step, will allow the timeous assessment of the occurrence and extent of pollution, and assist with the proactive management of groundwater pollution in South Africa.