City stares at water shortage as northeast monsoon stays thrift

The northeast monsoon, the primary rainfall season for Tamil Nadu, usually makes a landing from October to December, bringing an average of 789.9 mm rains. However, this year so far, the city has received only 205.9 mm rain, less than half of the normal that it should have received in the same period — 499 mm.

In the last four years, the city has faced a rain deficit only in 2016 when it received only 342.1 mm of rainfall for the entire season. The Chennai district received only a meagre 72.9 mm of rainfall for the months of October and November. However, the situation was tackled with the help of tanker lorries and water supplied from the desalination plants.

The years that sandwiched that difficult season witnessed floods and cloudburst, which helped raise groundwater levels in 2015 and 2017. In 2015, the city received only 27.4 mm in the month of October. But it all changed by the time the season came to a close – the cumulative rainfall that year stood at a whopping 1608.6 mm. It was similar in 2017, when the eventual figures showed 937.8 mm rains.

Making clear the difference between the two years, the four city reservoirs had a total storage of 1,630 million cubic feet (mcft) on Saturday, a far cry from the 4,504 mcft that these lakes had on the same day last year.

The metropolitan city requires about 830 million litres of water a day (mld). Among the various water sources that the water managers tap to meet the demand, these large reservoirs account for more than half (51 per cent). Veeranam lake (19 per cent), desalination plants (17 per cent), Krishna river (11 per cent) and open wells (1 per cent) supply the rest. 

After the disappointment that the monsoon has been so far this year, the water managers have put their hopes on the forecast by the Regional Meteorological Center, Chennai, that the city – and State – would receive rain in the next two days. The city is expected to receive rain or thundershower at isolated places in the next 48 hours.

“After wreaking havoc, the cyclonic storm Gaja has moved over to interior Tamil Nadu and now lies over southeast Arabian Sea as a deep depression,” said S Balachandran, deputy director general of RMD.

In the last 24 hours, the maximum amount of rainfall was recorded in Sivagangai district (17 cm). The other places included Kodaikanal (14 cm) and Thammampatty (Salem district) with 10 cm of rainfall.

Scattered heavy rains, which would strengthen into isolated but very heavy rain is likely to occur over Tamil Nadu and Puducherry on November 20 and 21.

Under the influence of the cyclonic circulation over Malay Peninsula and adjoining equatorial Indian Ocean that now lies over south Andaman sea, a low-pressure area is likely to form over central parts of south Bay of Bengal by Sunday evening.

Fishermen are advised remain on the shores, as squally winds with the speed about 65 kmph is likely over southwest Bay of Bengal.