Among the impacts of climate change will be an aggravation of water quality in South Africa’s rivers and dams; this may, in turn, lead our water authorities to raise the bar for water discharged by industry and mines.
“Variable rainfall patterns occasioned by climate change are already being seen in more frequent high-intensity downpours in parts of the country,” said Manda Hinsch, partner and principal water and environmental scientist at SRK Consulting. “This means high-velocity run-off, accompanied by both increased leaching of soil nutrients and fertilizer and wash off of urban pollutants– which end up in our water impoundments.”
Global research confirms that more intense precipitation and increased runoff means more pollution entering waterways in the form of sediments, nitrogen from agriculture, disease pathogens, pesticides, and herbicides. One of the more dramatic consequences can be blooms of harmful algae and bacteria.
The steady and ongoing enrichment of water with nutrients gradually reduces its quality, with significant implications for the environment and for downstream use, said Hinsch. Where these heavy rainfall events are interspersed with hot, dry periods, high levels of evaporation could further increase the concentration of nutrients.
On the other hand, water quality is also likely to be compromised in areas where climate change is leading to less rainfall. She said that these negative impacts on water quality will exacerbate an already problematic situation, where the widespread malfunctioning of municipal wastewater treatment works is contributing to low-quality discharge into rivers and dams.
She noted that many of the concerns expressed by the government and industry about climate change relate to the future changes in our water quantities – with insufficient attention paid to how the quality will change.
“In response to the declining quality of water, the relevant authorities may well have to take the further policy and regulatory steps,” she said. “Water legislation already governs the acceptable or target levels of contaminants the receiving water environment can receive in order to be suitable for downstream water users. Mines and industry; companies should not be caught unaware if water quality standards become more stringent in the future.”
Hinsch emphasised the integral connection between water quantity and quality when developing water management plans – be they for local government or private enterprises. While these plans need to be multi-faceted and focused on local conditions, there is a growing appreciation of the role of wetlands in water management.
“Wetlands play a vital role in controlling the flow of surface water and reducing run-off, while also trapping sediments and removing pollutants to help purify water,” she said. “We will hopefully see greater use of attenuation ponds and constructed wetlands as part of our national response to climate change and more variable rainfall patterns. The strategy can also be applied by mines and even certain industries.”
About: Manda Hinsch
Manda Hinsch, BSc (Hons) Water Utilisation, BSc Biochemistry & Chemistry is a Partner and Principal Scientist with over 34 years of experience in the fields of Project management and coordination of environmental impact assessments, environmental management programmes, water use licence applications and specialist inputs for mining and industrial projects, water quality management, water allocation and water allocation reform, water use efficiency; waste management, policy development; policy implementation, water resource management.
SRK – Manda Hinsch – water quality
