New Delhi, Dec. 1: India may need to brace itself for more frequent landslides, flash floods, crop damage and submerged towns as extreme rainfall events increase in number, scientists warned today.
Researchers who analysed the most comprehensive rainfall data from India compiled so far have found that both the number of heavy rainfall events and the amount of rainfall during such events have increased.
The number of very heavy rainfall events (150 mm or higher) in central India has more than doubled from about eight per monsoon to 18 over the past 50 years. The number of heavy rainfall events (100 mm or higher) in central India has also increased from 45 to about 65 in the same period.
The trends indicate “a large increase in disaster potential,” the researchers said, reporting their findings in the US journal Science. Discerning trends in extreme rainfall in the west, North- east and mountain regions is difficult because they have highly variable rainfall patterns.
“This finding need not create panic, but India needs to prepare itself for hazards from such events,” said team leader Bhupendra Nath Goswami, director of the Indian Institute of Tropical Meteorology in Pune.
“Extreme rainfall events develop fast and die fast,” Goswami said. “This makes it difficult to predict them. But improvements in forecasts could lead to forecasts two hours in advance,” he said.
The scientists used rainfall data, compiled by the Indian Meteorological Department from 1,803 stations, and combined data from many stations spread over large areas to pick out the changing patterns in extreme rainfall events.
While extreme rainfall events are increasing, the average rainfall has not changed because the frequency of light to moderate rainfall events has decreased. “The two trends cancel each other out,” said Vuruputur Venugopal, a research team member at the Centre for Atmospheric and Ocean Sciences at the Indian Institute of Science.
The scientists explained how global warming might lead to extreme events. “Rising temperatures will lead to greater moisture in the atmosphere. The more the moisture, the greater the instability in the atmosphere which, in turn, helps to produce deep clouds associated with heavy rain,” Goswami said.