Severe rainfall pounded several parts of the city and its neighbourhood on early hours of Thursday, November 11, 2021, as the depression over southwest Bay of Bengal moved towards TN coast.
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According to the IMD, the depression moved with a speed of 27 km per hour and was about 300 km east-southeast of Chennai and 280 km east-southeast of Puducherry. It is very likely to continue to move west-northwestwards and cross north Tamil Nadu and adjoining south Andhra Pradesh coasts between Karaikal and Sriharikota close to the north of Puducherry by Thursday evening.
As torrential downpour continued through Wednesday night, several weather stations in and around the city recorded a very heavy rainfall till 5.30 a.m. Ennore port ( 17.5 cm), MRC Nagar and Nungambakkam (14 cm), Villivakkam and Taramani– 12 cm, Meenambakkam (10 cm), Satyabama University (11.3 cm) and West Tambaram (9 cm).
Rains were more concentrated over Chennai and neighbouring districts as districts like Cuddalore and Tiruvannamalai recorded light to moderate rains.
The Meteorological department has said surface winds will be strong with wind speed gusting up to 45 km per hour over Chennai, Kancheepuram, Tiruvallur and Chengalpattu districts of Tamil Nadu and Puducheery during next six hours under the influence of Depression over South west Bay of Bengal off North TN coast.
In its Nowcast warning issued at 6.50 a.m., the department has warned of thunderstorm with heavy to very heavy rain likely at isolated places over Tiruvallur, Chennai, Chengalpattu and Kancheepuram within next three hours. Moderate rains may occur at isolated places over Cuddalore, Kallakurichi, Villupuram, Ranipet, Vellore, Thiruvannamalai, Kanniyakumari, Tirunelveli and Tenkasi and Puducherry during next three hours.
In Tiruvallur district, reservoirs that feed drinking water supply recorded an intense rainfall. Cholavaram recorded 22 cm, which is termed as extremely heavy rainfall. While Red Hills recorded 18 cm, Chembarambakkam 12 cm, Poondi received 9 cm. Nearly 88 out of 324 tanks have touched their full capacity so far till Thursday morning.
The Tiruvallur district administration and the Water Resources Department have increased the water discharge from Red Hills reservoir from 2,000 cusecs (cubic feet per second) to 3,000 cusecs at 7 a.m. The reservoir’s inflow went up to 10,000 cusecs. The water level stands at 19.20 feet against its full level of 21.20 ft.
Similarly, water release from Poondi reservoir too was increased from 5,000 cusecs to 6,000 cusecs at 7 a.m. as it received a heavy inflow of 8,000 cusecs. Chembarambakkam received an inflow of 5,240 cusecs and about 2,000 cusecs is being let out into the Adyar river.
