India Monsoons Intensifying, Hazard Risks Increasing, Study Says

Sean Markey
for National Geographic News
December 1, 2006

India's monsoon rains are getting heavier, with more severe weather likely in the future, according to scientists who examined daily rainfall records since 1951.

"The magnitude of the strongest events has increased substantially over the past 50 years" in central India, lead study author B. N. Goswami, of the Indian Institute of Tropical Meteorology in Pashan, said in an email.

"Such events are associated with flash floods and mudslides. [And] our results indicate increasingly higher potential for such hazards in coming years."

(Related photo: "Mouse Rides Frog in India Monsoon: [July 5, 2006].)

At the same time, days with light to moderate rains during the June to September monsoon period are decreasing, the team reports today in the journal Science.

Moderate rains are desirable because they more readily soak into the ground, watering crops and filling aquifers and wells.

Overall, the seasonal average rainfall has changed little since 1951, with today's more frequent downpours offset by more dry days.

Intensifying Rains

India's weather is governed by its prevailing winds, which blow out to sea during the long dry season.

During the summer monsoon season the wind direction shifts, bringing cooler, moist air from the Indian Ocean and Arabian Sea over the Indian subcontinent (India map).

In their study, researchers analyzed daily rainfall data collected from 1,803 sites across central India between 1951 and 2000.

The team found that the total number of days with heavy rainfall—defined as four inches (ten centimeters) or more—increased 10 percent a decade since the early 1950s.

Continued on Next Page >>


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