Kolkata Floods: Five Reasons Why Heavy Rains Paralysed The City In Six Hours (IN PICS)

Kolkata was paralysed as sudden heavy rains flooded streets, halted traffic, and disrupted transport in just six hours. The city received more rain in hours than usual, overwhelming drainage and causing chaos. Here are five reasons behind the deluge.

The flooding was caused by a low-pressure area over the northeast Bay of Bengal, which brought heavy rainfall to coastal areas of Gangetic West Bengal, including Kolkata, Hooghly, and Howrah districts. Unlike typical storms that move inland and weaken quickly, this low-pressure area remained stuck over the northeast Bay of Bengal for an extended period, continuously pumping moisture toward Kolkata like a stationary garden sprinkler storm intensified rapidly from a regular low-pressure area to a depression within just 24 hours, which is faster than normal.

Most Bay of Bengal systems also spread their rainfall over several days as they move across the region, but this one concentrated most of its impact during a single 6-hour window between midnight and 6 am. The scale of rainfall that hit Kolkata was truly extraordinary by any measure. In just 24 hours, the city received 247.4 mm of rain, which represents a staggering 2,663% more than the long-term daily average for Kolkata. To put this in perspective, the city got more than 26 times the normal amount of rain it would typically see in a single day. 

The sheer volume of water that fell in such a compressed timeframe completely overwhelmed Kolkata's drainage infrastructure, which simply wasn't designed to handle such an unprecedented deluge. As the city's storm water systems buckled under the pressure, widespread waterlogging spread across the metropolitan area, bringing normal life to a complete standstill. The flooding crippled the city's transportation network, with traffic systems grinding to a halt as major roads became impassable rivers, while both suburban train services and the Metro network were forced to suspend operations due to waterlogged tracks and stations

The timing of this devastating flood couldn't have been worse for Kolkata, as it struck just days before Durga Puja, the city's most important and celebrated festival. Durga Puja is not just a religious observance for Kolkata - it's the cultural heartbeat of the city, when millions of people travel to visit elaborate pandals (temporary structures housing goddess idols) across neighborhoods, turning the entire metropolis into a vibrant celebration that draws visitors from around the world. With waterlogged streets, suspended transportation, and safety concerns forcing authorities to advise people to stay indoors, the flood posed a serious risk to what is essentially Kolkata's equivalent of Christmas, New Year, and Carnival all rolled into one.

Unlike the typical gradual, multi-day rainfall pattern associated with Bay of Bengal systems, this event produced a“cloudburst-like” downpour over a densely populated metropolitan area with limited drainage capacity, overwhelming the city's infrastructure and leading to widespread waterlogging. Essentially, this was a "perfect storm" scenario where multiple unfavorable factors combined - a stationary, rapidly intensifying weather system that dumped its entire load during the city's most vulnerable hours.

MENAFN23092025007385015968ID1110099393