Using satellite data and regional climate models, IIT Bombay researchers have found that deforestation (converting woody savanna to crop land) in north-east India and north-central India has led to a 100-200 mm reduction in summer monsoon rainfall in these two regions. The land use information is based on satellite data for two time periods — 1980-1990 and 2000-2010. The results were published on August 24 in the journal Scientific Reports.
During the initial phase of a monsoon, oceanic sources play a major role in bringing rain and charging the soil with moisture. But at the end of the monsoon period, evotranspiration from vegetation contributes to rainfall. Evotranspiration is a local moisture source for rainfall. Recycled precipitation contributes to 20-25 per cent of the total monsoon rainfall during the end of the monsoon and is very prominent in the Ganga Basin and north-east India. “Because of deforestation, there is 1-2 mm reduction per day in rainfall during the end of the monsoon in the Ganga Basin and north-east India,” says Prof. Subimal Ghosh, the corresponding author of the paper from the Interdisciplinary Programme in Climate Studies, IIT Bombay.