It is becoming increasingly important for mines to stay up to date with the latest monitoring technology to ensure water resources are efficiently monitored on site, both from a water management point of view and from a compliance and legislative point of view, says SRK principal hydrologist Peter Shepherd.
He explains that one of the technologies gaining traction in water resources is the use of satellite remote sensing technology to measure and monitor evaporation across a broad spatial scale.
“Remote sensing satellites that contain both visible and thermal bands can measure energy emitted from the earth’s surface. [By] using surface energy balance models . . . total evaporation of the land surface can be calculated across a landscape at a variety of different scales.”
Shepherd adds that remote sensing enables the remote monitoring of the presence and surface distribution of moisture on tailings storage facilities (TSFs) on a regular timescale – in this case, every two weeks, depending on the weather – and at a sufficient spatial scale.
He says the remote sensing application will allow for monitoring surface seepage, position patterns, evaporation and the persistence of surface moisture on the TSF, providing valuable data to better inform water balances and TSF designs.
Shepherd says that remote sensing has been used on several mines in South Africa, and particularly over the TSFs, to measure evaporation as an indicator of seepage, as well as the persistence of moisture deposited with the slurry. He credits Lauren Bulcock, a former employee of SRK, with introducing this finding through her doctoral work in South Africa.
“Already this information has proved useful to our clients to identify if and where surface seepage is occurring, allowing them to concentrate their efforts on drilling recovery boreholes to contain those pollution plumes,” says Shepherd. He adds that these measures have saved clients unnecessary expenditure in developing exploratory boreholes and, moreover, assisted in targeting boreholes where seepage is identified.
“The use of remote sensing to measure and monitor evaporation is a relatively new scientific field worldwide and has mostly been applied to agricultural applications.” As such, apart from some local pioneers, very little to no remote water monitoring applications have been implemented in the mining sector.
“There is great potential for remote sensing to complement TSF monitoring programmes into the future to measure and monitor the spatial distribution of slurry surface moisture, surface drying time and leak detection, which will allow for the better management of tailings dams and improve input into water balances,” Shepherd concludes.