South Africa is experiencing a warming trend that is about 1.5 times the global average. Kirsten Kelly talks to Mehmetcan Özkadıoğlu, hydrologist at SRK Consulting, about the impact of climate change on mine water management.
“South Africa is currently undergoing notable climate transformations – a trend that’s becoming more and more evident,” explains Özkadıoğlu. “Climate change projections are predicting a temperature increase of 1°C to 2°C across the country by mid-century. Accompanying this, we are anticipating a shift in rainfall patterns, leading to an increase in rainfall for some of the areas and a decrease in overall rainfall trends in other areas, which could potentially lead to drier and wetter mining conditions. At the same time, the climate models project an increase in the intensity of rainfall and the frequency of storm events, increasing the risk of mine flooding. The probability of extreme heat events, which can intensify evaporative losses, is also expected to rise. These changing climate patterns are essential to incorporate in the mine water management strategies, highlighting the urgency of climate change considerations in our decision-making processes.”Climate change significantly impacts water resources, and the following are key considerations for the mining industry and mine water management in South Africa.
- Water scarcity: Climate change is projected to significantly impact on water resources, with a major concern being the potential decrease in water availability. This can result in water scarcity, posing a challenge to water-intensive mining operations.
- Extreme weather events: A key principle in thermodynamics is that as air temperature increases, so does the atmosphere’s ability to hold water vapour. This can lead to more severe and frequent storm events. These extreme storm events can disrupt mining operations, damage crucial infrastructures – such as stormwater structures, tailings, water supply dams, open-pit operations and waste rock dams, among others – and pose safety risks.
- Changes in water quality: Changes in temperature and precipitation due to climate change can affect the quality of water. Increased rainfall intensity, for instance, can lead to a rise in sediment loads in the surface run-off, affecting the quality of water used as the mine process water. On the other hand, decreased rainfall and increased temperature can result in higher concentrations in contact waters and reduce the water quality.
- Increased energy consumption: For mining operations that are delving deeper and encountering lower ore grades, there is an escalating demand for water and an increase in mine waste. This situation contributes to a rise in energy consumption and expands the industry’s carbon footprint.
- Reputational risks: Failure to adequately factor in the impacts of climate change on mining operations could lead to disputes with host communities, potentially affecting the social licence to operate, as water supply may be reduced for the communities.
Adaptive strategies and precautionsMining companies must anticipate different climate change scenarios and then consider the impact on the operational and closure phases of a mine’s life. There are various adaptive strategies:
Tailings storage facilitiesUnderstanding the potential impacts of climate change is key for the design, construction, operation, and closure of tailings storage facilities (TSFs). The Global Industry Standard on Tailings Management (GISTM) is a framework developed to prevent tailings dam failures. It aims to achieve the safe and secure management of tailings facilities by establishing clear expectations for companies, governments and other stakeholders. In the context of climate change, GISTM can help mining companies adapt by promoting the use of best practices in tailings management, considering climate change in risk assessments and improving the resilience of tailings facilities to extreme weather events. “The design and construction of current tailings dams have not fully considered the fluctuating climate patterns and the recent intensification of extreme weather events. It is now imperative to incorporate planning for an uncertain climate future into risk management strategies. Take, for example, the lifespan of certain tailings dams, which are projected to continue operation for the next three to five decades before the closure phase. Despite their closure, these dams will continue to be vulnerable to the impacts of climate change. Therefore, it’s critical that we factor in future climate conditions not just during the operational stages, but also throughout the subsequent closure and post-closure phases of these dams,” says Özkadıoğlu. Considering a future where a region experiences a rise in rainfall patterns, it’s essential to acknowledge the impact this shift in rainfall pattens will have on a range of operational aspects, hydrological and hydraulic processes. These include, but are not limited to, the infiltration of precipitation into TSFs, the decant from the TSF impoundment area, and the storage conditions of both the TSF and downstream return water dams. TSFs must be capable of storing and effectively releasing extreme storm volumes to prevent uncontrolled discharges from TSF. The design of diversion channels, which redirect excess run-off away from the TSFs, may need to be re-evaluated in response to these changes.
The increase in air and surface temperature, alterations in wind patterns, variations in cloud cover, and other factors will affect the evaporation process. Additionally, it is important to consider that extreme weather events may potentially cause damage to the structure, necessitating a more resilient and robust design. The impacts of climate change will vary for each mine, depending on its specific location.