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Professor Rafael L. Bras, head of the Department of Civil and Environmental Engineering, has received the 1998 Clarke Prize for excellence in water research, awarded annually by the National Water Research Institute (NWRI) of Fountain Valley, CA.
Professor Bras is an internationally recognized researcher in hydrology and hydroclimatology whose work encompasses many aspects of the Earth's water cycle. His research in real-time flood forecasting 20 years ago changed the way that predictions are made today. He and his research team have recently designed an even better way to predict when rivers will overflow, based on the incorporation of detailed topographic data and radar-based rainfall measurements.
It was for this and his other exceptional work in hydrology that Dr. Bras was selected as this year's $50,000 Clarke Prize winner. He received the prize and presented the Clarke Lecture on May 29 in a ceremony in Costa Mesa, CA.
"I'm delighted and honored to win the Clarke Prize, and I'm especially honored to be the first hydrologist selected for this distinction," said Professor Bras. "The hydrologic cycle is the circulatory system of the living Earth. It behooves us to understand that system and protect it. I'm grateful to the NWRI for its promotion of those efforts."
The Clarke Prize was established in 1993 by the NWRI and its founders, Athalie Richardson Irvine Clarke and her daughter, Joan Irvine Smith, to recognize scientists and engineers of exceptional ability and to promote research and technology in water.
"With a remarkable career reflecting a continuing series of significant accomplishments, Dr. Rafael Bras is recognized worldwide as a singular driving force in the hydrological sciences. His research has helped to increase public awareness of the key role water plays in maintaining the quality of life on this planet," said Ron L. Linsky, executive director of the NWRI.
In addition to his work in flood forecasting, Professor Bras, the Bacardi-Stockholm Water Foundations Professor at MIT, has ongoing research projects in remote sensing and modeling of precipitation and soil moisture, the fractal organization and geometry of river basins, modeling the geological evolution of river basins, and, most recently, monitoring and modeling the impact of deforestation in the Amazon river basin using data from a NASA satellite launched in November 1997.
"Like our circulatory system, the hydrologic cycle moves water throughout the body-Earth," Dr. Bras said in the Clarke Lecture. "[It] is an exquisitely intertwined and balanced interaction between atmosphere, oceans and land. But it is a very sensitive, complicated and fragile system, particularly relative to human needs."
In recent work on flood forecasting, Dr. Bras and his co-researchers focus on the river basins in the Earth's complicated hydrologic system, creating a mathematical model to predict how water will flow during heavy rains.Their distributed real-time flood forecasting model exploits data from high resolution digital terrain maps, coupling it with radar-based rainfall measurements to more accurately predict in real-time the way that water will behave in river basins.
The new distributed model, which has been tested in several locations, including the Arno River near Florence, Italy, differs from more traditional "lump" models by its treatment of a river basin as a collection of many data points of rainfall measurement and topography.
"The old 'lump' models treated an entire river basin as one point. But in reality, precipitation is sporadic. It's very discontinuous in space and time," said Professor Bras, who explained that modern methods of measuring precipitation by radar provide precise measurements every 2 square kilometers. Old methods used a rain gauge every 2,000 square kilometers, he said. The new distributed models incorporate all that data, and use it in real time to anticipate how rivers will behave during extreme events, such as heavy rains or droughts.
"I think the differences are going to be quite significant when you go to medium and large size basins. Especially with intense storms," he said.
Professor Bras hopes that the work will lead to more accurate flood forecasts by the National Weather Service, the Army Research Office and the Government of Italy, all sponsors of the research.
Dr. Bras, a native of Puerto Rico, was named one of the top 100 most influential Hispanics in the United States last year by Hispanic Business magazine. He holds the BS (1972), the SM (1974) and the ScD (1975) from MIT. He has received numerous other awards and has authored two textbooks, three other monographs and more than 100 articles.
He is also a consultant to industry and governments throughout the world, and recently chaired an international panel of experts charged with the preparation of an environmental impact statement on sea gates to protect the Venice lagoon and the city from flooding.
In a letter supporting the nomination of Professor Bras for the Clarke Prize, Dr. Stephen J. Burges, professor of civil engineering at the University of Washington, said, "Rafael Bras is leading the nation's top civil and environmental engineering department as it prepares to lead the profession in these exciting and changing times. Once a generation we see a colleague of Dr. Bras's capabilities."
A version of this article appeared in MIT Tech Talk on June 3, 1998.