Civil Engineering June 2022 | Vol 30 No 5

Civil Engineering June 2022 23 in outflow structures. Mines have been paying more attention to these aspects, including the increased use of automatic water level sensors within TSFs, flow measurements in drains and trenches, and in site-wide reticulation. The GISTM will undoubtedly lead to an acceleration in this trend, as well as the frequency of monitoring. Rather than monthly or weekly analyses of data collected, this should ideally be done continuously in real time using telemetry monitoring systems. This will require mines to scrutinise the gaps in their monitoring and metering network more closely to ensure that the resulting data can effectively inform short-term and long-term actions. Responding to the GISTM’s water balance concerns will need a better understanding of evaporation fluxes and variability. Measuring evaporation from TSFs is a field of growing interest and research, with important gains being made in the scientific assessment of what has previously been an estimation. While annual potential evapotran- spiration in semi-arid environments like Southern Africa reaches volumes often exceeding three times the annual rain- fall, the actual evaporation volumes from the TSF are controlled by the hydraulics of the porous medium. An improved knowledge of evaporation effects assists design engineers to understand the de- velopment of the pore water flow within the body of the TSF – allowing better assessments of TSF stability to be made. Beyond the on-site water balance and actual water volumes and fluxes in the TSF, best practices in water management emphasise a broader water stewardship approach. A leading mining company has even targeted zero use of fresh water on its mines, recognising that water conflict could threaten its social licence to operate. These pressures for water stewardship beyond GISTM standards speak to trends emerging in the public space, guiding mines to adopt water strategies that will build resilience within the business. In future, such an approach is likely to be vital when accessing finance and markets.  Measuring evaporation from the surface of platinum tailings using the surface renewal technique Predictions are that by 2025, South Africa will be an extreme water scarce country... Scan me !