By Alisha Rahaman Sarkar

Copyright independent

At least 10 people died after record rainfall triggered severe flooding and paralysed Kolkata just as the eastern Indian city was preparing to celebrate its biggest festival.

Kolkata and its suburbs received the heaviest rainfall in almost 40 years, flooding roads, knocking out power in many areas for hours, suspending train services, and grinding daily life to a halt on Tuesday.

The city by the Bay of Bengal received 251.4mm rainfall between Monday night and Tuesday morning, making it the sixth wettest day in 137 years, local media reported.

Nine of the 10 people who died were reportedly electrocuted.

The city is currently illuminated with thousands of decorative lights ahead of Durga Puja, a Hindu festival celebrated with great pomp and fervour.

Kolkata comes alive in a grand spectacle of light as thousands of elaborate, temporary structures rise up every year for the five-day worship of goddess Durga. Durga Puja in the city is on the UN’s list of the “Intangible Cultural Heritage of Humanity”.

The city’s weather office recorded 252mm of rain in just five hours on Monday. The heavy downpour was triggered by a low-pressure area in the Andaman Sea, officials said.

The system moved towards the coastal areas of Gangetic West Bengal and adjoining regions on Monday morning, causing a strong convergence of moisture over Kolkata.

“Moisture-laden clouds stayed over Kolkata for hours. Their height ranged between 5km and 7km from the surface,” HR Biswas at the Regional Meteorological Centre in Alipore told The Telegraph.

He ruled out a cloudburst as the cause of the excessive downpour, explaining that a cloudburst “involves much taller cumulonimbus clouds and a deafening roar in most cases”.

The weather department ruled out heavy rain in the city over the next 24 hours but predicted mostly cloudy skies with light to moderate showers. Authorities, though, warned that another low-pressure area was “likely to form over the northwest and adjoining central Bay of Bengal” around Thursday.

The flooding situation was worsened by the closing of lock gates to keep out high tide in the Hooghly river just as the downpour intensified at night, leading to water bodies overflowing.

The city administration declared holidays for all schools and colleges until Friday as its workers struggled to pump out floodwaters from the inundated streets a day after the downpour. Pictures on social media showed people wading through chest-deep water.

At least 90 flights had been cancelled by late evening on Tuesday, and as many delayed. The disruption comes at a time when the Kolkata airport witnesses heavy traffic due to the Durga Puja festivities.

The chief minister appeared to blame CESC Limited, the biggest supplier of electricity in Kolkata, for the electrocution deaths.

“The CESC must look into this. They have to take responsibility,” Mamata Banerjee said. “I am tired of saying this.”

She said the power company should offer jobs to family members of the victims as well as compensation of Rs500,000 (£4,172) to the kin of each of them. Ms Banerjee added that her government would ensure jobs to the next of kin of the victims.

“Electricity is supplied by CESC, not us. It is their duty to ensure people do not suffer because of this. They will do business here, but will not modernise here? They should send people to the field and fix this,” she said.

She claimed that the situation in Kolkata was compounded by floodwaters flowing in from neighbouring states.

“To those commenting on social media, I urge you not to politicise this crisis,” she said.

The power utility company shot back on Tuesday, claiming that street lights and traffic signals were maintained by the state administration. “We have investigated eight such cases. We found that in five of the cases the deaths were caused by electrocution from faulty wiring within homes or a factory,” CESC said in a statement.

Three of these deaths happened outside, it added, with two caused by electrocution from touching street light poles.

“These street light poles are generally not owned or maintained by CESC. The other case was from a kiosk near a traffic signal,” it said.

The company said it would be able to restore power only after it had been informed by “appropriate authorities that the water has receded to safer levels”.

Several areas, mostly in southern Kolkata, suffered without power for almost 12 hours on Tuesday.

The CESC claimed it had restored up to 60 per cent of its citywide operations by Tuesday night and “expected to restore everything in the next few hours”.

Climate experts say rising global temperatures are contributing to an increase in sea surface heat, which leads to more rainfall in coastal regions and melting of glaciers in the Himalayas, causing catastrophic flooding and landslides in the South Asian region.