This batch of showers will decide the future of city’s water supply

The city, which is in need of rain, may get some respite this weekend. A well-marked low pressure area, now lying 700 km east of Parangipettai in Cuddalore district, may intensify and bring rainfall over the city.

The downpour from this depression could possibly ameliorate the water situation in the city.

The city receives its major share of annual rainfall of 140 cm during the northeast monsoon. On an average, Chennai gets rainfall of 80 cm between October and December. However, since October 1 this year, the city has got only 22 cm, which is a deficit by 38 per cent for the season.

Officials of the Meteorological department said the well-marked low pressure area is expected to intensify into a depression, and bring rains over Chennai and its neighbourhood as well as coastal districts of Tamil Nadu from Friday. Surface winds could be gusty at times due to the low pressure area.

Y.E.A. Raj, deputy director general of meteorology, Regional Meteorological Centre, Chennai, said, “We are monitoring the weather models and tracking the movement of the system. Many coastal districts would receive a good rain spell if the system crosses between Nagapattinam and Cuddalore.”

On the fog that residents in south Chennai have reported, he said it was a local phenomenon, rare in November. It could occur when the minimum temperature drops and the dew point temperature remains stable.

Reservoirs’ storage remains low

A heavy rain spell would not just recharge groundwater but also help resume daily drinking water supply. Officials of Chennai Metrowater said a good rain spell is essential to fill the reservoirs that are the main sources of drinking water supply to the city. At present, the four reservoirs in Poondi, Red Hills, Chembarambakkam and Cholavaram have a combined storage of 2,715 million cubic feet (mcft), which is only 25 per cent of their capacity.

Due to the dipping resources, Chennai Metrowater was forced to reduce the volume of supply from 830 million litres a day (mld) to 575 mld. In May, it had started providing water on alternate days to the city. The water agency would be able to resume daily water supply only if the reservoirs’ storage reaches a comfortable level, officials said.

“We need about 8,000 mcft in reservoirs to start supplying drinking water daily. Last year, about 6,000 mcft was added to the storage in the water bodies during the northeast monsoon. This year, since last month, the storage has gone up by only 500 mcft so far,” said a source in Metrowater.

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