AS A RESULT of groundbreaking research on the links between river flow and river health spearheaded by Dr Jackie King of UCT's Freshwater Research Unit in SA through the 1980s and 1990s, she became a founder member and, in 2002, team leader of the World Bank's advisory group on the sustainable use of rivers. The team is one of 12 advisory groups within the World Bank's newly formed Water Partnership Programme funded by The Netherlands.

What caught the eye of the World Bank were two methods developed in South Africa by King and colleagues for advising decision-makers on the way the conditions of river ecosystems would change if their flows were altered, eg by damming. Previously most methods came from the United States where their main purpose was to advise on flows for maintaining fish populations.

"The world's methods did not meet southern Africa's needs adequately," King explains. "A local approach was initiated because in our arid and semi-arid climates it was essential to find ways of managing the health of the whole river ecosystem, not just the fish. We also needed to take into account the millions of subsistence users of rivers in southern Africa whose lives could be devastated by an upstream dam decimating their resources."

A case in point, says King, is the Lesotho Highlands Water Project. When the Katse Dam filled, a few hundred people were displaced, but the management of river flows from the dam are continuing to impact the lives of hunderds of thousands of people downstream. The Lesotho and South African governments are currently negotiating on how much water should stay in the rivers to maintain an acceptable condition and how much should be abstracted for use elsewhere.

The science of advising on environmental flows – water flows that are left in, or released into, a river system with the specific purpose of managing some aspect of its condition – is less than 50 years old. More than 100 methods currently exist for environmental flow assessments and at least 30 countries are using them routinely in water resource management, with the number growing annually.

Their purpose can be as general as maintaining a healthy river ecosystem, or as specific as enhancing the survival chances of a threatened fish species. They can target the river channel and its surface waters, groundwater, the estuary, linked wetlands or floodplains, the riparian zone, and/or any plant or animal species associated with any of these system components.

The first method developed in South Africa is called the Building Block Methodology (BBM). The comprehensive BBM Manual, published in July 2000, was the result of a decade of extraordinary co-operation between government and South Africa's national body of aquatic scientists, water managers and engineers.

One of only a few advanced environmental flow methods in the world with a formal manual, the BBM also had a major influence on South Africa's new National Water Act of 1998, because it convinced the lawyers writing the Act that water needs for keeping rivers healthy could be quantified. The new Act recognises only two rights to water – one for basic human needs and the other for maintenance of aquatic ecosystems.

"Our Water Act is one of the most advanced in the world and the envy of other countries," says King.

First introduced in a workshop for the Lephalala River in the Northern Province near the Botswana border in February 1992, the BBM was developed through application in a series of real South African water-resource development projects. The 1996 BBM workshop for the Sabie-Sand River in the Kruger National Park was one of more than 15 BBM workshops for different local rivers, organised and funded by the Department of Water Affairs and Forestry (DWAF) and the Water Research Commission, which aided the development of the BBM.

The second method, DRIFT (Downstream Responses to Imposed Flow Transformations), evolved from the BBM to address the need to provide a number of flow/river health scenarios for decision-makers to consider. It has a more comprehensive socio-economic component than the BBM, and so the impacts subsistence users face when their rivers are dammed can be described in detail. It has been welcomed internationally as arguably the best method available to predict the impacts of water-resource developments on rivers and riparian people. DRIFT was developed by King and colleague Dr Cate Brown of the UCT associate consultancy group, Southern Waters.

Both the BBM and DRIFT are routinely used in South Africa, to advise DWAF on options for flow management, and are increasingly being applied elsewhere, notably in Lesotho, the US, Australia and Zimbabwe. DRIFT is also being modified for use in south-east Asia where King acts as World Bank advisor on river flows to the riparian countries of the lower Mekong River (Vietnam, Thailand, Laos, Cambodia). The World Bank has approached Southern Waters to develop training courses in the methods, with the first courses probably to take place in Tanzania and Lesotho.

According to King, one of the most important consequences of these two holistic approaches to flow management is the collaboration and communication they have encouraged between many physical, biological and social scientific disciplines, and between scientists, engineers, water managers and decision makers. "This co-operative work has resulted in a massive growth in cross-disciplinary research and training in South Africa.

"This is already feeding through to undergraduate teaching, while the senior scientists soon identify which areas they need to research in order to improve their advice to managers. The Water Research Commission has been the major supporter and funder of such research. Many countries are now sourcing BBM/DRIFT-trained scientists from South Africa."

Another important outcome is that the methods provide decision-makers with information they have never had before on the predicted ecological and social impacts of water-resource developments. They now have to consider this as well as the traditional engineering and economic information on costs of construction and commercial value of the extracted water.

It makes their decisions more difficult as they search for the best trade-off, but hopefully more balanced. The methods have enabled the sustainable use of rivers to be placed firmly on the negotiating table.

King is currently in Australia as advisor to the Queensland government on their strategies for managing river health, and also as reviewer of the environmental flow strategies being employed to manage the health of the Murray–Darling River, the country's largest river system.