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WHILE SA's attention is fixed on acid mine drainage and its implications for the country's water resources, eutrophication is quietly thriving in the background.

Eutrophication is mainly brought about by pollutants entering water bodies, causing a build-up of nitrates and phosphates. These pollutants are a rich nutrient for some algae, which then flourish and greatly reduce oxygen levels, disrupt natural ecosystems and cause high levels of poisonous cyanobacteria.

"It's a serious problem," says Prof Eugene Cloete, dean of science at Stellenbosch University and chairman of the advisory board of the Stellenbosch University Water Institute. "It's a longer-term threat from acid mine drainage and (requires) more remedial effort . 25% of SA's dams are in a eutrophic state. We can't remove the toxins . with our usual (water) filtering techniques, and the techniques that exist are very expensive."

One of the main impediments to addressing the problem is a lack of data on what is happening in SA's coastal and inland water resources.

"Monitoring is problematic in SA. We used to have good monitoring infrastructure but the Department of Water Affairs does not have the people any more to do this and the monitoring system fell apart," Prof Cloete says.

The Safe Water Earth Observation Systems unit of the Council for Scientific and Industrial Research (CSIR) says that "there is little understanding of the mechanisms by which eutrophic states occur (and) national policies require the establishment of a national system for measurement and management". The unit set about developing low-cost water observation technology, a mixture of satellites and buoys fitted with sensors.

Project leader Stewart Bernard says: "For sea and inland waters, it's very expensive to make the measurements you need as often as you need. A research vessel at sea will cost R100000 for a day." That is prohibitively expensive and does not allow for continuous monitoring of systems.

The unit's plan for routine, real-time monitoring of water bodies consists of satellites and autonomous systems such as buoys or robotics. "Other buoys exist in SA, but they are geared to the physics of the ocean. The technology is not suitable for inland or near-shore waters.

"It is low-cost but that means $15000-$20000 (a buoy)," Dr Bernard says. "Our aim is to make systems that cost that amount in rand."

Completely funded by the CSIR, the project has been allocated R7,5m over three years.

It is a surprisingly simple idea: a 3m x 1m, 50kg pencil buoy with several sensors, each monitoring different environmental variables.

"The main sensors are radiometers, which measure the colour of the light (underwater). From this we look at the optical properties of, say, cytoplankton and put it into an algorithm (a mathematical model). And from there, we can find out how much cytoplankton is there, its size, etc."

Other sensors monitor temperature, wind speed, water current speed and GPS. "Those data are extremely useful to (determine) how the ecosystem is functioning, changing temperatures, wind patterns," Dr Bernard says.

The buoy is powered by a 12V battery, which is charged through two 10W thin-film solar panels, and contains a 2Gb onboard data storage facility. The data can be communicated via cellphone signal to a central data processor.

The buoy takes measurements every half an hour, while a satellite takes a measurement once a day. "The combination of a buoy and a satellite cross- checked against the buoy is a powerful data-collection method," he says.

Prof Cloete questions whether the technology will be able to differentiate between silt and the toxic algae, but says that it is "definitely a step in the right direction".

However, the goal remains extensive, detailed observation data. "The buoy is still in the demonstration phase," Dr Bernard says. "It'll be a year or two before we're rolling it out.

"Building a buoy and putting it in the water is the beginning of the problem.

"Keeping it there and keeping it running is the difficult part," he says.

Initial trials were held in September last year, and the buoy is now undergoing sea trials in the Southern Benguela, one of the world's most productive ecosystems.

The next stop will be Loskop Dam in Mpumalanga.

"We hope for a mass roll- out, which we're anticipating in the next three to five years.

"It takes that amount of time to develop the hardware and systems and learn from your mistakes," he says. "It's all South African. It's designed here. It's made here. All with the view to rolling it out."

wilds@bdfm.co.za