资源环境科技发展态势分析平台

Tamhini, a station located in the leeward side of northern parts of Western Ghats (WG) of India, receives a mean-monsoon rainfall of 6498.4mm. The station has no record of any meteorological agencies in India. Therefore, the existence of such heavy rainfall (HR) station remained unknown. In this study, many special features of Tamhini rainfall have been discovered hitherto unknown to monsoon meteorologists. Statistical analysis of daily rainfall data of monsoon season (June-September) of Tamhini for the period 1975-2013 has been carried out. The analysis showed that in spite of lying on the leeward side of main WG, Tamhini's monsoon rainfall is more than that of stations lying on the windward side of the WG. This is in contrast to widely accepted view that rainfall is lower on the leeward side of mountains. Tamhini rainfall ranks number one in the north Peninsula and fifth in India. It is more compared to Cherrapunji monsoon rainfall (second highest rainfall-receiving station in India) in 8 non-El Nino years. It has the highest 1-day (695mm) and 3-day (1055mm) rainfalls in the Peninsular WG region. There are many extended HR spells during the season with a mean duration of 10 days. Other stations in the same area viz. Mulshi-camp, Shirgaon, Davdi and Ambawane also receive high monsoon season rainfalls. Area-mean rainfall of the region has been studied to understand the frequency distribution of HR spells. Such spells are of concern as total accumulated water during these spells is conducive for occurrence of floods. No significant trends in Tamhini and area-mean seasonal and HRs are observed. 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.