Famed for its tea, Assam’s tea garden records are giving scientists a glimpse into past rainfall changes in northeast India, plagued by scattered and spotty historical rainfall data.
For 12 years, the scientists and students at Cotton University in Guwahati, Assam, combed through handwritten tea garden records spanning 1920 to 2009, to reconstruct a 90-year daily rainfall dataset.
The reconstructed dataset aims to fill in the gaps in historical rainfall observation network by the India Meteorological Department and generate a new baseline for rainfall in the northeast. This will help analyse and address the impacts and risks due to extreme rainfall, in improved ways.
Using the data mined, they were able to identify and highlight the increasing frequency and intensity of extreme rainfall in northeast India through the past century, while the average rainfall has decreased.
“The rain comes in short spells; the spells are no longer well distributed in space and time like they used to be 30-40 years ago,” Rahul Mahanta, who led the reconstruction, told Mongabay-India during a visit to the university just days before the Assam floods disrupted life, in June 2022.
Surrounded by registers from tea gardens with yellowing pages, sprinkled generously with dates and numbers in spindly handwriting, Mahanta narrates the story behind…