CHENNAI: At a meagre 168.4 mm, the north-east monsoon from October 1 to December 31, was the second worst season in 150 years, which followed a deluge in the northern part of the State just a year earlier.
The erratic change in climate, said V Selvam, Executive Director, MS Swaminathan Research Foundation, would show that “We were at the cusp of a climate transition.” He said, “The transition is, however, a gradual process; these extreme weather events could be an indication of it.” The change in ocean surface temperature, for instance, could lead to erratic cloud formation- sometimes large clouds, sometimes none at all. However, the rainfall statistics, especially the historic figures of 2016 that has been repeatedly cited as the reason for the present shortage, has not convinced all water experts.
“This is a man-made drought, as were the floods the last season. We did an analysis of rainfall trend for the past 125 years, but couldn’t find a decline as is being said. There might be a fluctuation, but there’s no decline,” insisted hydrology expert S Janakarajan.
The stark contrast between the Januarys of 2016 and 2017 has also highlighted the failure in storing rainwater that could have mitigated the situation to a large extent. “If the rainfall received in 2015 had been stored optimally, it would have served Chennai city for around five years,” said R Emaraj, retired Chief Engineer of PWD’s water resource organisation. But the reservoirs have a total capacity of 11 thousand million cubic feet, or only about a year at best, going by the demand of around one tmc a month, he said.
According to Janakarajan, reservoirs cater to only 20 per cent of drinking water needs, with groundwater contributing to the rest. “We should recharge groundwater on a war footing. Even with 39,000 tanks across the State and 10,000 temple tanks, ground water is still the primary source,” he said.
The government has decided to desilt 12 tanks below sill level (the bottom of the sluice) to facilitate sub surface storage, but experts say the effectiveness has to be seen.
Officials say although the government is prepared for the worst, it hopes that the Meteorological Department’s prediction of summer showers would come true. But experience has shown surviving on monsoon-to-monsoon is poor water management.