Spotlight

New Delhi, 7 May 2007

EXCESSIVE RAINFALL IN INDIA PREDICTED

NEW DELHI, May 8 (INFA): Recent studies conducted by scientists from various research institutes in India indicate the possibility of the country heading towards excessive rainfall in the coming decades, possibly triggered by a warming earth.

Researchers from the Indian Institute of Tropical Meteorology (IITM), Pune, and the Indian Institute of Science, Bangalore, who recently published a paper in the journal Science, say extreme rain events have grown both in number and intensity over large parts of Central India in the span of half a century.

The analysis was based on daily rainfall pattern during the south-west monsoon from 1951 to 2000 in an area of about 1.4 million square km in central India, extending from Uttar Pradesh in the north to Andhra Pradesh in the south and from Madhya Pradesh in the west to Bihar in the east.

According to study, instances of heavy rainfall, where places in Central India received 10 cm or more of rain in a single day during the monsoon, had increased at a rate of 10 per cent every decade since the early 1950s. In addition, several areas were receiving more rain than before. The study warns that the increasing trend in extreme rainfall events over Central India could continue for the next decade or two.

The study further revealed that the increase in extreme rainfall events occurred during a period when the waters of the tropical Indian Ocean became warmer, production more water vapour.  IN addition, temperatures over India increased by 0.5⁰ C in the last 50 years. The capacity of the atmosphere to hold moisture increased due to these factors and hence conditions became conducive for heavy downpours.

In a separate paper published in early 2006, another group of researchers at the IITM also predicted an increase in severe rainfall activities across an extensive area covering the Western Ghats, Maharashtra, southern Gujarat, and parts of Central India by the end of the 21^st century. The scientists, who published their work in the journal Current Science, used a regional climate model to examine climate change scenarios that India might face.

A similar study at the India Meteorological Department’s National Climate Centre in Pune, after examining rainfall data from 100 observatories across the country, found that extreme rainfall events during the south-west monsoon had increased significantly between 1901 and 2000 along the west coast, Maharashtra and southern Gujarat.

Erratic rainfall pattern was observed in many other parts of the country as well. A study by the Central Soil and Water Conservation Research and Training Institute, Dehradun for the period 2071-2100, shows that annual rainfall would increase by 3.4 per cent in Nilgiris in Tamil Nadu and by 47 per cent over Umiam in Meghalaya, while winter rains would decrease over Tehri Garhwal.

In 2005 and 2006, the country also witnessed a unique shift in the monsoon rainfall pattern-heavy rains in drought prone areas like Rajasthan and scanty rainfall in flood-prone areas like Assam and other north-eastern Stats.

Although no analysis has been done to establish a direct connection with the increasing trend of extreme rain events and global warming, the scientists agree that the trend appears to be consistent with the global warming phenomenon as demonstrated from model simulations and physical considerations.---INFA