The city’s upkeep crew were put on notice by the first spell of heavy rain in what usually is the rainiest month in Calcutta.

Several roads were waterlogged after the rain, mostly between 3am and 10am.

The Met office recorded around 50mm of rain in Alipore. Figures obtained from the drainage pumping stations of the civic body showed that Ballygunge was the wettest part, recording 99mm of rain in the same period. Paikpara got around 68mm, Palmer Bazar 61mm and Maniktala got 59mm.

In Met parlance, 60mm of rain in 24 hours qualifies as heavy. This was the heaviest rain in Calcutta in July so far this year.

By 8am, several parts of Central Avenue and MG Road were under ankle-deep water. Lamp posts and traffic signal posts near the intersection of MG Road and Central Avenue have been painted with yellow markers at the bottom to gauge the level of waterlogging. On Friday morning, the water had nearly touched the six-inch mark.

The cover of a manhole on Central Avenue, near Yogayog Bhavan, was kept open for the water to pass, under the supervision of a man from the civic body.

Around 10.30pm, the Patipukur underpass was so waterlogged that traffic police had to prevent two-wheelers and small vehicles from approaching it. A barrier of guard rails had been set up to divert them. Only big vehicles were allowed to cross the underpass.

A flooded Patipukur underpass on Friday morning

This newspaper has reported multiple times on how the clogged drains and gully pits contribute to waterlogging. At the Nabanna tirade on June 24, chief minister Mamata Banerjee had lashed at the civic body for clogged drains.

But in many parts of Calcutta, the drains are still choked with plastic and precious little has been done to clean them.

Tarak Singh, the mayoral council member in charge of drainage in the KMC, blamed a familiar foe.

“The lock gates of the drainage channels that open into the Hooghly were shut from 3am to 6am. The intensity of the showers was the highest at that time. Our drainage network is capable of draining out up to 30mm of water in an hour. But if the lock gates are shut, there is little we can do,” said Singh.

Fewer pupils

The showers led to a dip in attendance in some schools and delayed arrivals in many.

At St James’ School, about 30 per cent of the children were absent.

“Students were absent in most classes,” said principal Terence Ireland.

The turnout was lower in junior classes in some schools.

Those who turned up got delayed because of the rain and traffic. Schools that are otherwise strict about attendance were more relaxed on Thursday.

Mahadevi Birla World Academy and Sushila Birla Girls’ School allowed students to walk in late.

“We gave students a grace period because there was traffic snarls in the morning,” said Nupur Ghosh, vice-principal, Mahadevi Birla World Academy.

At Sushila Birla Girls’ School, some of the students were late by almost half an hour.

Two systems

Two systems combined to trigger the rain in Calcutta.

“A trough runs from Assam to the northwest Bay of Bengal. A cyclonic circulation persists over sub-Himalayan Bengal. It extends till Malda and surrounding regions,” said a Met official.

“Rain is likely in Calcutta on Saturday and Sunday. Monday and Tuesday are likely to be drier,” he said.