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Thursday, September 24, 2020

Explained: Why does Delhi’s Minto Bridge underpass keep getting flooded?

Waterlogging under the Minto Road railway bridge is an almost inevitable monsoon event in the capital. The problem lies in the natural gradient of the land, the heritage bridge that cannot be easilt re-engineered, and the larger issue of Delhi’s choked and dysfunctional drainage system.

Written by Mallica Joshi , Edited by Explained Desk | New Delhi | Updated: July 22, 2020 11:04:14 am
Minto Bridge, Minto Bridge floods, Minto Bridge waterlogging, Delhi news, Delhi rains, Delhi floods, Delhi rains video, Minto road railway bridge A flooded Minto bridge on Sunday. (Express Photo: Prem Nath Pandey)

Over the years, the picture of the bus stuck under the Minto Road Railway Bridge, which is officially called the Shivaji Bridge, has become an inalienable part of the monsoon in Delhi. The pictures come every year, and a series of governments, scores of engineers and PWD officials, have failed to do anything to stop the waterlogging on one of central Delhi’s main streets.

What is the problem? Why does the area get waterlogged every year?

As is evident to everyone who has travelled down the road, the underpass below the bridge is a low-lying patch, surrounded on all sides by areas at a higher elevation. This bowl-like depression is a natural receptacle for rainwater, with no outlet for the accumulated pool.

The road meets Connaught Place’s Outer Circle at one end, Shahjahanabad at the other, DDU Marg on the third, and the New Delhi Railway Station on the fourth. All these areas are at a higher elevation, and the runoff during heavy rain leads to the bowl under the underpass getting inevitably filled.

Minto Bridge, Minto Bridge floods, Minto Bridge waterlogging, Delhi news, Delhi rains, Delhi floods, Delhi rains video, Minto road railway bridge Workers clean the mud at the Minto Bridge underpass in New Delhi on July 20, 2020. (Express Photo: Praveen Khanna)

The Public Works Department has installed pumps – temporary and permanent – at the site over the years, but a permanent solution has been elusive.

The railway bridge was built in the 1930s after the seat of power of the Raj moved from Calcutta to Delhi. It is a listed heritage structure, so there is little that civic or government agencies can do in terms of redesigning it.

In fact, a plan to demolish the bridge and redesign the area as part of expansion of the New Delhi Railway Station was floated in 2008, ahead of the Commonwealth Games, but it never took off.

Without a redesign, PWD officials say, it is tough to find a permanent solution, given the natural slope of land in that area.

So what happened on Sunday (July 19), the most recent time when Minto Road was flooded?

Last year, the Aam Aadmi Party government had said that the area wasn’t waterlogged because a drain that has been closed off at DDU Marg, near the BJP headquarters, had been cleared.

Sunday evening, however, showed the relief was only temporary. The PWD, Delhi Jal Board, and the municipal corporations started trading blame in the evening after a man drowned in the water under the bridge.

Government officials said the Covid-19 pandemic had a role to play in Sunday’s waterlogging, not just at Minto Road but also in other areas in the city. With workforce diverted to sanitise houses and containment zones, and in other Covid-related work, the desilting of drains has been hit, the officials said.

Complaints of waterlogging came from 102 areas across the city, not just Minto Road.

Watch | 10 shanties collapse in Anna Nagar after heavy rains in New Delhi

Minto Bridge, Minto Bridge floods, Minto Bridge waterlogging, Delhi news, Delhi rains, Delhi floods, Delhi rains video, Minto road railway bridge DTC buses seen stuck at Minto Bridge in July 2018. (Express Photo: Prem Nath Pandey)

And was this because the rainfall was particularly heavy in Delhi on Sunday?

Delhi got 74.8 mm of rain in a span of around 3 hours on Sunday morning — which is pretty heavy.

However, while this was the highest of the season so far (the season has just about begun, though), and also the most rain that the city has experienced in a single day in July since 2015, it was nowhere near the all-time record for the month of July in Delhi.

Thus, in 1958, the city received 266.2 mm of rain in a single day in July. And more recently, in 2013, it got 123.4 mm of rain in a single day in that month.

According to India Meteorological Department (IMD) data, Delhi receives a little less than 30 days of rain through the year. Almost 20 of these days are during the southwest monsoon period.

Also, data show a trend towards isolated, very heavy rainfall events contributing to the bulk of the total precipitation, rather than rainfall spread more evenly over the length of the monsoon season. Thus, 95% of Delhi’s total monsoon rainfall is recorded in just 99 hours.

Minto Bridge, Minto Bridge floods, Minto Bridge waterlogging, Delhi news, Delhi rains, Delhi floods, Delhi rains video, Minto road railway bridge At a flooded Minto Bridge in August 1987. (Express Archive/S Paul)

OK, the situation at Minto Bridge aside, why do so many other places in Delhi see waterlogging every monsoon?

The primary reason is that Delhi’s drainage system, which is a combination of old, Raj-era drains and a few newer ones, does not function efficiently. According to an IIT Delhi report on drainage in Delhi, the city has 426.55 km of natural drainage lines and 3,311.54 km of engineered stormwater drains — but many are compromised.

According to a report submitted in 2015 by a committee set up by the National Green Tribunal, of the 201 natural drains that existed in the city in 1976, as many as 44 could no longer be traced.

Stormwater drains are largely channels that have been carved up by the natural flow of water. All of them are supposed to eventually lead to Yamuna so that the runoff is deposited into the river. These drains need to carry water uninterrupted when heavy rain occurs.

In the city, however, many of these drains have been blocked, encroached, or built upon. The blocking of the drains for purposes of construction, diverting water, or storing it for treatment does not create a major problem for most of the year because Delhi does not see a lot of rain in the non-monsoon months from October to June.

During the monsoon, however, and especially during a heavy or extreme rainfall event, water accumulates on the roads and in parks. Experts have long said that the best way to avoid flooding during the monsoon is to ensure the drains are allowed to flow unimpeded and take the water to the Yamuna, as they have done for centuries.

The second reason is the concretisation of open spaces.

As footpaths, roads and walkways are concretised, rainwater cannot seep into the ground. This also results in a fall in the water table. While the use of perforated tiles to allow seepage, leaving unpaved surfaces along the roads, and building rainwater harvesting tanks in big buildings and areas was earlier advocated and later mandated, the situation on the ground remains unsatisfactory.

The third reason is that throughout the non-monsoon months, debris and garbage are dumped in the stormwater drains. Desilting is carried out only before the monsoon months, and is hardly ever completed before the rains hit. The accumulated garbage ends up impeding the flow of water.

Minto Bridge, Minto Bridge floods, Minto Bridge waterlogging, Delhi news, Delhi rains, Delhi floods, Delhi rains video, Minto road railway bridge Cleaning the drains near Minto Bridge. (Express Archive/R K Dayal)

So what can be the solutions to this situation now?

As Chief Minister in 2012, the late Sheila Dikshit had asked IIT Delhi to prepare a drainage master plan. The draft report was submitted in 2016, and the final report in 2018.

The first challenge for the researchers was to obtain data to work with. According to the report, it took them over 100,000 hours to collect the data needed to create a model for efficient drainage.

This was primarily because of poor maintenance of records, and the multiplicity of agencies. In Delhi, drains are managed by the municipal corporations, the PWD, and the Irrigation and Flood Control Department, along with other smaller agencies. While PWD and the irrigation department come under the state government (now with the AAP), the BJP is in power in the corporations. This makes coordination tougher and shifting blame easier.

During the study, IIT Delhi researchers found, along with other issues, sewage flowing into drains that are meant to carry only runoff — either because households did not have sewer connections, or because the Delhi Jal Board, which handles all sewage lines in the city, had punctured holes in sewage lines and diverted the flow into stormwater drains to ease pressure and blockages.

Among the suggestions made in the IIT Delhi report was to make sure that drains are treated as key public assets, and that no encroachments are allowed. It also said that raw, untreated sewage should not be let into drains, and that all stormwater drains should be put under a single agency.

Most of these suggestions remain unimplemented.

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