Wetlands are getting less and less rainfall

BANGALORE: Rainfall has been decreasing in Kodagu, Chikmagalur and Dakshina Kannada districts over the last 100 years. DK received an annual rainfall of 3,653 mm in 1901 (111 years ago), while in 2008 it stood at 3,441 mm. The same with Chikmagalur district — from 1,927 to 1,872 mm. “In a global phenomenon, coastal areas are getting lesser amount of precipitation.As the rainfall in the interior parts increases, a balance needs to be maintained. In the hilly areas, rain is decreasing due to vegetation loss,’’ said MB Rajegowda. The quantum of rainfall remained the same for 20 years (1901 to 1920) before it came down marginally in the next decade. For the next 50 years, the rainfall was swinging by a few mm. It was only in 1971-1980 that the state’s rainfall touched the 1300 mm mark.After 1991 when Karnataka recorded the highest ever rainfall of 1350 mm, the state has not crossed the 1,300 mm mark, says BK Ramachandrappa, chief scientist (dry land agriculture) at UAS.CLOUD COVERSouth-west monsoon normally sets in over the extreme southern parts of the state by June 1 and covers the entire state by June 10. The rain months — July and August — account to about 25% and 18% respectively of annual rainfallCLIMATE CLASSThree climatic classes are found in the state: arid, semi-arid and humid. The mean annual rainfall varies from 400mm in the eastern parts to more than 4,000mm in the Western Ghats and coastDRY FACTSWhile Rajasthan is the worst hit, Karnataka stands second in terms of total geographical area prone to drought. Nearly 90% of the population in this semi-arid region is dependent on agricultureWHAT IS THE 16-YEAR CYCLE The scientists stumbled upon a definite cycle of 16 years, eight of which receive above normal rainfall and the rest less than normal. If one half of the cycle receives less than normal rainfall (say from 1950 to 1958), the other half receives more than the normal amount. During this half of the cycle, two or three years would have received rainfall opposite to the trend. “When we analyse data, we try to generate common features and understand the trend. The 16-year cycle is something that became obvious during our analysis. This is part of a global phenomenon and was noticed from 1950,” said Rajegowda.WE ARE IN FOR BAD TIMESIf one goes by the cycle, the positive eight years of the cycle has been completed and the negative cycle has begun now. One negative cycle in Karnataka began in 1998. The state experienced droughts for three years since 2001.The next eight years lifted the spirits of farmers in the state. Bangalore Urban district, for instance, received rainfall above the 1,000-mm mark in 2005 and 2008. However, the positive cycle has ended and Karnataka is in for tough times again. “According to the cycle, the negative cycle has begun. There might be one or two years that will buck the trend. Otherwise, the rainfall would be below the normal amount for the coming years,” Rajegowda said.