Bangladesh flood and drought forecasting could bring farmers, cholera victims relief

November 13, 2001

A cooperative new research project studying oscillations in the Indian Ocean and rainfall in the major river basins pouring into Bangladesh should help researchers better forecast floods and the associated spread of cholera in the low-lying nation.

University of Colorado at Boulder Professor Peter Webster, of the Program in Atmospheric and Oceanic Sciences, said a joint effort between CU-Boulder, the Asian Disaster Preparedness Center and the Bangladesh government could improve the quality of life for millions of people. In addition to forecasting monsoon variability and associated sea rise leading to flooding and cholera outbreaks, the team should be able to forecast local and regional droughts, further aiding Bangladesh farmers.

The project had its beginnings in 1999, when a study of Indian Ocean monsoons involving a number of universities and federal agencies showed the ocean has its own El Niño-like phenomenon. Led by Webster, the research team crisscrossed 10,000 miles of the Bay of Bengal aboard the National Oceanic and Atmospheric Administration ship, the Ron Brown, measuring water temperature and salinity gradients to depths exceeding 1,500 feet.

The team also used radar, weather balloons and satellites to determine the Indian Ocean monsoon season has three active periods and three calm periods. The El Niño-like conditions are characterized by an east to west movement of warm water that causes "edge waves" to slosh up the east coast of the Bay of Bengal, flooding the Bangladesh delta on a time scale of about two years, said Webster.

"The ocean rises up into the delta, retarding the outflow of water," said Webster. Most of the retarded outflow is floodwater from rainfall in major rivers that drain into Bangladesh, including the Ganges, Brahmaputra and the Meghna rivers.

The weather and climate system forecasts are produced with computer modeling from probability statistics, each beginning with slightly different initial conditions, said Webster. Fifty-one short-term global forecasts are produced by the European Centre for Medium Range Weather Forecasts every day for 10 days. Webster and his team use the data to pinpoint India and South Asian conditions, specifically the probability of precipitation in the Ganges River catchment area that is roughly the size of the Mississippi Valley.

"Although Bangladesh is about the same size as Colorado, we need to know the oceanic conditions over the entire Indian Ocean and rainfall in all of the catchment areas of the three main river systems, he said. "All river outflow eventually must pass through the Bangladesh River Delta." The European weather forecasts also model global weather patterns for six months, which are used by the Bangladesh team, said Webster.

Cholera is an intestinal disease caused by tiny parasitic crustaceans known as copepods. Research has shown that copepods thrive when plankton blooms in the ocean as the water warms, contaminating rivers as the sea invades the delta. At any given time, more than half the Bangladesh population may be infected with the disease.

"We feel we can accurately predict sea-surface temperatures, rising waters in the delta and extreme rainfall or drought conditions," said PAOS research associate Robert Grossman. "By localizing our forecasts, we can provide individual communities with probabilities regarding floods and associated cholera outbreaks, as well as droughts."

The implications of floods and droughts reach beyond agriculture into the arenas of hydroelectric power, fuels, water storage, and even the banking industry, Grossman said.

"Bangladesh farmers understand the concept of probabilities and do what they can to minimize risk," said Grossman.

"We want to work with individual farmers and be able to quantify that our forecasting scheme has a positive impact on subsistence farming. Our goal is to change the concept of minimizing risk to optimizing opportunity, and to integrate our technology-transfer with already existing agricultural knowledge of Bangladesh farmers."

The research effort has implications for other countries with deltas and large river catchments, including India, Thailand, Vietnam and Cambodia. "What began as a flood forecasting plan has turned into a broader study of climate change," said Webster. If sea rise in the region increases 1 meter by 2050 as some models indicate, half of Bangladesh will be underwater, displacing 100 million people.

"We now understand the physics of the ocean and the monsoons pretty well," said Webster. "The challenge is to take our forecasts to the people and improve their livelihoods. This project shows CU is at the center of a major practical science effort, and demonstrates what university science can really accomplish."

The PAOS team was awarded a three-year, $1 million grant for the project from the U.S. Agency for International Development. "Since 65 percent of the world's population is subsistence farming families living in monsoon regions, our vision is to create a Center for Monsoon Studies at the university," said Webster, who involves more than a dozen post-doctoral researchers and graduate and undergraduate students in his research.

"Ideally, we would like our center to be a non-governmental organization funded by private gifts from donors," he said. "Understanding the physical and biological sides of monsoon activity will allow us to work directly with the Bangladesh people and help improve their lives."
Robert Grossman, (303) 492-8932
Jim Scott, (303) 492-3114

University of Colorado at Boulder

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