1996: Jörg Imberger, Australia

Professor Jörg Imberger is an environmental engineer with an interest in how water moves and how substances disperse in stratified bodies of water. Often lakes are the focus of his attention, but he also studies streams and rivers, estuaries, lagoons, reservoirs and coastal waters.

Professor Jörg Imberger, University of Western Australia- Stockhom Water Prize 1996
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Jörg Imberger is seen as a landmark in this area of research. The most respectful commentators talk about “before and after Imberger.”

Most bodies of water become stratified, for example as a result of differences in salinity or temperature. Winds and natural movements of the water are not always able to generate sufficient mixing to affect the water at greater depths. Consequently, a given volume of water may exhibit widely varying characteristics. Several of the patterns of motion which Imberger is studying used to be unknown.

In the course of his research, Imberger has also developed, in collaboration with industry, a wide range of sophisticated instruments. They have been vital to his research aims, which have proved to be the mother of invention. Imberger lowers one of the instruments he has devised into the Swan River, within sight of the skyscrapers of his home city of Perth. In appearance, it is reminiscent of a milking machine; in practical and technical terms, it has numerous functions. Precise data on a dozen important parameters, measured at each of the depths investigated, appear on the screens of two laptops on deck, which are hooked up to the instrument. The professor’s doctoral students keep a watchful eye on the results, and a printout is produced with a dozen curves showing physical, chemical and biological data from the different levels of the water column studied.

“By comparing flux paths with data from the different levels, we’ve been able to build computer models that can be used to predict how contaminants will behave and how quickly they will be diluted.”

Jörg Imberger

On larger computers back at the University of Western Australia, Imberger and his students can monitor spectacular graphic models, whose behaviour changes according to the parameters fed into them. A wave movement pulsates in different colours across the screen. The effects on the motion of deeper layers of water can also be seen.

This approach offers a better understanding of water-related environmental problems, and a better basis for tackling them. And it allows the future responses of aquatic environments to be predicted with greater certainty, in advance, say, of development projects or planned discharges. These are just some of the potential environmental benefits of Jörg Imberger’s research.

The global span of Professor Imberger’s work was another factor behind the decision to award him the Water Prize. To give just a few examples of the projects simultaneously claiming his attention, he is studying internal waves in tidal flows in the Netherlands, ways of maintaining water quality following the building of the Bakun dam in Borneo, the impact of bottom topography on water motion in the Valdivia estuary in Chile, the effects of waves on the biogeochemical balance of Lake Kinneret in Israel, the amounts of wastewater a reservoir in Brazil can absorb, and transport mechanisms in Lake Biwa in Japan and their consequences.

The benefits of his global experience are, perhaps, the next generation of water researchers. Professor Imberger was responsible for initiating the first environmental engineering course in Australia and also founded the Department of Environmental Engineering at the University of Western Australia. Professor Imberger’s achievements are all the more noteworthy since, as a researcher, he has gained worldwide eminence, but he is equally committed to improving outcomes for students.