The tourist destination of Tamhini Ghat near Pune, situated on the crest of the Western Ghats, records the fifth highest monsoon rain, scientists at the Indian Institute of Tropical Meteorology (IITM) Pune revealed. Strangely, the station finds no mention in government records.
The finding was based on a statistical analysis of daily rainfall data between 1975 and 2013.
In fact, Tamhini’s seasonal rainfall in eight different years between 1975 and 2013 was more than that of Sohra, erstwhile Cherrapunji, which was once considered the wettest.
With an average rainfall of 6,498.4mm during the monsoon, Tamhini ranks fifth alongside Mawsynram (8,864mm) and Cherrapunji (8,633mm) in Northeast, and in the Western Ghat regions of Amboli (7,071mm) in Maharashtra and Agumbe (6,866mm) in Karnataka.
But what has caught the interest of monsoon scientists is the quantum of rainfall Tamhini receives every year despite being located in the leeward (drier side) of the Western Ghats.
“Tamhini receives more rainfall than locations on the windward side of the Western Ghats. This is in contrast to widely accepted view that rainfall is lower on the leeward side of mountains,” said a senior scientist at IITM who is not authorised to talk to the media.
The Western Ghats causes seasonal rainfall (June–September) of 2,500 mm and above on the windward side of the Ghats.
The researchers said heavy rainfall in the coastal areas and the Western Ghats is due to winds from the Arabian Sea that directly hit the mountain ranges. As a result, Mahabaleshwar and Agumbe which fall on the windward side of the Ghat region receive heavy rainfall.
“For long, our understanding was that it rains more in the coastal areas or on top of mountains. Though, it rains on the other side of the mountain ranges as well, it is not as much as the windward side.” said JR Kulkarni, retired scientist and the co-author of the study. “We, therefore, need to know mechanism for heavy rain on the leeward side of the hill.”
The weather station at Tamhini along with four others was set up as per World Meteorological Organisation norms by Tata Power Company 40 years ago as part of its hydroelectrical power project.
The Tata station was not part of the rain-gauging network of the India Meteorological Department, which is under the Union earth sciences ministry.
The highest rainfall-receiving station in the north-western Ghats, Tamhini also beats Mahabaleshwar, which receives an average rainfall of 5425.9mm between June and September.
With 695mm rainfall in June 29, 1994, Tamhini has become one-day highest rainfall station in peninsular India, beating Agumbe (620mm) and Mahabaleshwar (458.5mm).
“The discovery of this station has shown the occurrence of high rainfall on the leeward side, which is a unique feature in the orographic rainfall distribution in the world,” read the paper published in the ‘International Journal of Climatology’.