It is becoming increasingly important for mines to stay up-to-date with the latest monitoring technology to ensure water resources are monitored efficiently on site, both from a water management point of view and from a compliance and legislative point of view. One of the technologies gaining rapid 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. Using surface energy balance models, such as SEBS (Su, 2002), total evaporation (ET) of the land surface can be calculated across a landscape at a variety of different scales.
Remote sensing allows for the remote (from any computer with internet connection, from anywhere in the world) monitoring of the presence and surface distribution of moisture on Tailings Storage Facilities (TSFs) on a regular time scale (in this case every 2 weeks – weather depending) and at a sufficient spatial scale (30m resolution for free, higher resolution images incur a cost). Remote sensing will allow for monitoring the surface seepage, position patterns, evaporation and the persistence of surface moisture on the TSF. This provides valuable data to better inform water balances and TSF designs.
Remote sensing has been used on several mines in South Africa, and particularly over the tailings storage facilities, to measure evaporation as an indicator of seepage and to monitor the persistence of moisture deposited with the slurry. Lauren Bulcock, formerly with SRK, introduced this finding through her doctoral work in South Africa. Already this information has proven useful to our clients to identify if and where surface seepage is occurring, allowing them to concentrate their efforts in drilling recovery boreholes to contain those pollution plumes.
This has saved clients unnecessary expenditure in developing exploratory boreholes and assists 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. Very little to no applications have been done in the mining sector.
There is great potential for remote sensing to complement TSF monitoring programs 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 improved input into water balances.
