Technology solution to surveying Acid Mine Drainage unveiled

South Africa’s prosperous mining industry has contributed heavily towards the economic growth and wellbeing of the country. However, the downside to mining activity is that, overdensity of crush sand used for construction time, the intensive mining activity has unleashed an ecological process causing water in underground mines to become contaminated with heavy metals – often radioactive in nature.

Due to natural phenomena the water levels eventually rise to such an extent, that they begin to decant into rivers and streams. When the toxic water flows outwards into streams, river, towns and cities, in large quantities, this is referred to as Acid Mine Drainage (AMD) The first reports on AMD appeared in 2002, when rain resulted in flooding and 20 million litres of AMD water flowed into the West Rand Basin per day. Since then, many reports, articles and statistics have been compiled on the effects of AMD, as well as what the future holds for the South African environment.

Luckily, in today’s advanced technological environment, there are many tools that can assist in assessing the extent of damage done by AMD, as well as help with forward planning in terms of long-term management of the issue. The main concern with AMD is the fact that it can mix with drinking water, endangering humans, animals and people. Reports state that up to 80 % of South Africa’s drinking water may become undrinkable by 2015. This daunting statistic is set to become a reality if we do not act now against the problem of AMD.

Says Peter Moir, Chief Executive of Southern Mapping, “Often with environmental problems, the extent of the damage – and ways to curb it - is easier to measure by taking a bird’s eye view. This is exactly what hyperspectral surveying offers”. Hyperspectral technology, which has been available in South Africa for a number of years, offers a potential solution to identifying the problem.

The technology can accurately measure mineral precipitates on the banks of rivers and provide indications on the level of AMD contamination and water ph as well as directly measure chlorophyll a and b concentrations (direct functions of the amount of human and animal effluent) Hyperspectral technology attempts to simulate the natural abilities of certain animals and insects, by being able to decipher and hone in on unique and specific parts of light, or the electromagnetic spectrum.

The technology can be simplified as follows: Everything on the surface of the earth absorbs and reflects light differently in many parts of the electromagnetic spectrum. When sunlight strikes a leaf, light with the longest wavelength (red) and shortest wavelength (blue) is absorbed by the green matter (chlorophyll) in the leaves. In between these two colours there is green light which is reflected by the leaf; hence it has a green appearance to the human eye.

Everything on earth has a light signature and simply put, hyperspectral imaging is the science of measuring these signatures. “When utilised properly, hyperspectral technology, which is a technology offered by Southern Mapping, can help aid the fight against Acid Mine Drainage by providing information that would otherwise either be unattainable, or take a considerable amount of time to obtain,” concludes Moir.