Did over 100 mm of rain in an hour lead to Delhi deluge? Why does Capital struggle with flooding? – Firstpost

The rain gods unleashed their fury on India’s capital on Wednesday night (July 31), bringing Delhi and its adjoining areas of National Capital Region to its knees. Heavy rainfall submerged the streets, caused flights to be delayed and even death and destruction came calling.

In light of such a situation, the Delhi government announced that all schools would remain shut today — on August 1. Moreover, India’s weatherman, the Indian Meteorological Department (IMD), has issued a red alert warning, urging citizens to stay at home and avoid travelling.

But what caused this rain fury? And how bad is the destruction caused by it? Here’s what we know so far.

A cloudburst?

On Wednesday evening, Delhi turned into a watery mess after it experienced heavy rainfall in a short period of time. The capital recorded more than a hundred millimetres of rainfall in one hour, leading to waterlogging in several areas of the national capital and prompting the weather office to issue a ‘red’ warning.

As per the IMD’s Automatic Weather Station (AWS) network, the Pragati Maidan observatory in central Delhi recorded 112.5 mm of rainfall in one hour.

Incidentally, the IMD describes extreme rainfall in a short period of time, specifically 100 mm of rainfall within an hour, as a “cloud burst”. However, officials haven’t termed this rainfall to be the impact of a cloud burst.

But then what caused this sudden, heavy rainfall? The IMD around 7 pm on Wednesday said on X: “Clouds have converged over Delhi from all four sectors. Widespread light/moderate rainfall with isolated intense to very intense spell (3-5 cm/hr) likely over Delhi during the next two hours.”

Later, the IMD also forecast that the rainy conditions would continue until August 5.

A caved in portion of a road near Hauz Khas after heavy rainfall, in New Delhi. PTI

How bad was the rainfall?

Torrential rainfall unleashed chaos in the national capital on Wednesday, inundating large parts of the city. This led to unending traffic snarls, and people being stranded on roads that resembled rivers.

In Ghazipur, located in east Delhi, a woman and her three-year-old son fell into a waterlogged drain and drowned. The police in its report identified the victims as Tanuja and Priyansh, adding that they were out to buy household items when they slipped and fell into the drain. The incident occurred near the Khoda Colony area, where the roadside drain was under construction.

According to reports, three others in Gurugram aalso died in the deluge, taking the death toll to five.

Police personnel and others during a rescue operation at Sabzi Mandi area after a house collapsed following heavy rainfall, in New Delhi. PTI

The heavy rainfall also led to a house collapse in north Delhi’s Sabji Mandi area near Robin Cinema, injuring one person. Authorities also reported a wall collapse in southwest Delhi’s Vasant Kunj, in which a woman was injured.

In Pragati Maidan area, officials recorded 112.5 mm of rain within an hour, leading to waterlogging and a mess. The IMD also recorded 79.2 mm of rainfall between 5.30 pm and 8.30 pm at Safdarjung. In the same timeframe, Mayur Vihar saw 119 mm of rainfall, while Delhi University saw 77.5 mm of rainfall, Pusa saw 66.5 mm and Palam recorded 43.7 mm of rainfall.

Waterlogging in Lutyens’ Delhi caused bad traffic snarls, with people complaining on social media about the roads and the watery mess. Visuals from many places across Delhi showed vehicles wading through waterlogged roads while traffic police personnel tried to manage vehicular movement.

One image shared online also showed rainwater gushing into the Press Club of India, where people were seen sitting in knee-deep water. In other parts of the capital, visuals showed water gushing into showrooms and restaurants. Some parts of Delhi even lost power in the rains, with many residents being forced to sit in darkness for hours.

Incidentally, Old Rajinder Nagar, where students were protesting the death of three UPSC aspirants due to flooding in a coaching institute basement, was under knee-deep water.

People wade through a waterlogged road during rain at Jangpura area, in New Delhi. PTI

The weather also affected air traffic. At least 10 flights scheduled to land at the Delhi airport were diverted — eight to Jaipur and two to Lucknow — due to inclement weather conditions. Airlines also warned of the possibility of more flight disruptions.

The downpour and the subsequent water mess prompted Delhi Lieutenant Governor V K Saxena to ask officers to remain on alert. Meanwhile, Delhi Education Minister Atishi announced that all schools in the city will remain closed on Thursday. “In light of the very heavy rainfall this evening and the forecast of heavy rainfall tomorrow, all schools both government and private will remain closed on August 1,” she posted on X.

Why does Delhi struggle with flooding?

Wednesday’s rain caught Delhi unaware, as they have been witnessing a dry spell and sweltering heat. However, Wednesday’s rain chaos isn’t new to the capital. Delhi and the surrounding NCR region battles with flooding almost every year.

But what is the reason for this mess? Experts note that Wednesday’s rain was torrential and unexpected. It was, as they say, too much, too soon. As per records, parts of the capital saw over 100 mm of rain within an hour.

Waterlogging near the Bharat Mandapam during rain, in New Delhi. PTI

But it’s not just the unprecedented rain that leads to this flooding. Unchecked and ill-thought-out urban expansion is also a reason for Delhi struggling. According to data from NASA’s Earth Observatory, the geographic size of Delhi almost doubled from 1991 to 2011.

However, this expansion hasn’t taken the area’s topography into consideration. Manu Bhatnagar, principal director, Natural Heritage Division, INTACH, explained to Indian Express, “Topography determines drainage patterns. If one looks at Delhi’s historic cities — from Tughlakabad, Mehrauli, and Shahjahanabad to Civil Lines, New Delhi, and the Cantonment area — all were carefully selected, and built on higher ground. In Delhi’s villages too, the centre of the village would always be five to six metres higher than the village periphery.”

This allowed rainwater to drain out. But as the city has expanded, not enough thought has gone behind the building with regards to the land’s drainage capacities.

A car damaged under the debris of Happy School’s boundary wall that collapsed due to heavy downpour, in Daryaganj area, in Delhi. PTI

The constant construction also doesn’t help. Concretisation leaves little room for rainwater to percolate into the soil, leading to flooding.

The constant encroachment on the Yamuna floodplains is also to blame for Delhi’s flooding woes. Lakhs of people live on the floodplains of the Yamuna in the city, several of whom have converted the area to agricultural fields to make a livelihood. According to a report by the Centre for Science and Environment, the Yamuna floodplain had over 600 wetlands and waterbodies, but “more than 60 per cent of them are without water, making the city prone to flooding.” The report further states that “the river-fed water bodies in the Yamuna floodplain are disconnected from the river because of embankments.”

With inputs from agencies

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