IIT researchers find changes in summer rainfall pattern in

River basins having surplus water have experienced decreased rainfall while those with deficit water have seen an increase in precipitation, a study by IIT researchers on Indian summer rain pattern has revealed.

The study conducted by a team of researchers from IIT-Madras and IIT-Bombay also found that regions with excess moisture in the air do not always experience more rainfall from convection process, contrary to the common belief.

The team was studying the rainfall pattern during Indian summer monsoon period during the last 100 years, a statement from IIT Madras said.

The study has been published in the reputed peer-reviewed journal PLOS.

"River basins having surplus water have experienced decreased rainfall, whereas those with deficit water have seen an increase in amount of rainfall," IIT-M said about the study.

This observation is important, it said, because it contradicts the traditional notion of dry areas becoming drier and wet areas becoming wetter in response to climate change.

On the rainfall from convection process, the study found regions with excess moisture in the air did not always experience more rainfall, contrary to a common belief.

"It is common knowledge that geographic variation of extremes in rainfall occurs due to convection. And that would mean that regions where there is excess moisture in the air should experience more rainfall," it said.

"This, however, was not seen in the rainfall pattern analysed by the research team," the study said.

The research team comprised IIT-Bombay's Dr Subimal Ghosh and Dr Subhankar Karmakar and IIT Madras' Dr K S Kasiviswanathan, Dr K P Sudhir and Dr Sachin Gunthe besides their research students.

The outcome of the study would help in understanding geographic variations in seasonal rainfall in India, besides coming in handy to policy-makers, it said.

Indian summer monsoon (South West Monsoon) sets in over the country between June and September bringing around 80 per cent of the annual total rainfall and it plays a decisive role on the country's agricultural output.