Delhi and its neighbouring cities received 228.1 mm of rain yesterday, wreaking havoc on its daily life, with widespread waterlogging, traffic snarls, and disruptions to public transport. Some reports said that 10 people died as a result of yesterday’s events in the Delhi-NCR region.

There was widespread speculation that the heavy rainfall was caused by a cloudburst. However, the India Meteorological Department (IMD) clarified this morning that even though the event did meet the criteria for a cloudburst, which is 100 mm of rain falling within one hour, the downpour was not a result of such an event.

The Secretariat spoke to Sankalp Suman, deputy head at Energy and Environment–ISMA, who explained that even though there has not been a drastic increase in the amount of rainfall in the last 20 years, the real story lies in the intensity of these rainfalls.

“Earlier the same amount of rainfall would happen over 60 days but now it has come down to three days,” said Suman. “For example, in agriculture, for crops to grow you need the rain to be spread out, but if all of the rain happens in two days, then your whole crop gets hit.”

The capital was submerged in knee-high waters, hours-long traffic in waterlogged areas brought the city to a halt, many trees fell blocking the roads and forcing cars into single-lane traffic, a house collapsed in north Delhi’s Sabzi Mandi area and at least 10 flights were diverted to nearby airports in Lucknow and Jaipur.

Delhi’s Education Minister Atishi announced via X that all government and private schools in the capital will remain closed on Thursday.

But the biggest upset was the waterlogging caused by an unequipped drainage system in the city which is incapacitated to accommodate the city’s almost 3.4 crore population.

Capital Woe: Inadequate Drainage 

Delhi's drainage system, designed to handle only up to 50 mm of rainwater, struggles to cope with heavy rainfall. When rain exceeds this capacity, the system fails, causing significant disruptions across the city. 

For example, in July 2021, the Prahladpur underpass was severely waterlogged, submerging buses and highlighting the city's drainage challenges. A similar situation occurred last July when heavy rains and water release from the Hathnikund barrage led to flooding in key areas like Rajghat, Kashmere Gate, and the Ring Road near ISBT, affecting many commuters.

Wednesday too, these issues were starkly highlighted when a mother-son duo drowned after the son slipped into an invisible drain, hidden by floodwaters, and the mother fell in while attempting to save him in East Delhi’s Mayur Vihar Phase 3. 

These incidents underscore the urgent need for modernising Delhi's drainage infrastructure to cope with changing weather patterns and urban demands.

The IMD predicts more spells of heavy rain and thunderstorms over the weekend, however Mrutyunjay Mohapatra, Director General of IMD said less rainfall is expected in the month of August, in an online press conference Thursday morning.

“Very heavy rainfall was forecast yesterday early in the day. And then we started the ‘nowcasts’ as the day progressed starting at 4:30 PM. We said that Delhi will receive 3-4 mm per hour starting 6:30 pm. These nowcasts supported by all of our systems that this will happen,” said Mohapatra.

Coping With Excessive Rain: What Can Be Done?

Cleaning the drainage system is the first obvious measure that should be undertaken. Preventing waterlogging in vulnerable areas requires clearing the drainage system before the monsoon season arrives.

Regular cleaning of the roads and public spaces, raising awareness about public cleanliness, and imposing fines for littering can be supportive measures. Imposing an existing ban on plastic materials can immensely help here.

However, even a perfectly cleaned drainage system in Delhi will not be able to solve the problem of repeated waterlogging in the monsoon. The reason is Delhi’s archaic and antiquated drain design. The current infrastructure was designed much earlier to handle only 50 mm of rainfall in a day.

The existing drainage plan reportedly dates back to 1976, designed to accommodate the city’s population of around 3.5 million, at that point of time. As the population has increased nearly 10-fold, an update of drain design is a crying necessity.

 A Drainage Master Plan can address related problems, but it remains unapproved and has been pending for decades. 

Regular sewage and seasonal stormwater drainage systems ideally should be separated in a burgeoning city like Delhi. The length of the city’s natural (426.55 km) and engineered drainage-cum-stormwater (3314.54 km) networks have been proven to be inadequate after every heavy downpour.

Implementing an overall Sustainable Drainage System is also a need of the hour. Only an improved drainage cannot deal with sudden cloudbursts. Enhancing water absorption, minimising surface runoffs, and replenishing groundwater by integrating permeable pavements, green roofs, and rainwater harvesting are necessary steps to create a sustainable drainage system.

It may sound cliched, but integrating green and climate-responsive infrastructure is another crucial urban planning measure to deal with rain woes.

Introduction of green public spaces, vertical gardens, and larger tree cover across the city are some measures that can absorb extra water generated by cloudburst such as yesterday’s. However, then it becomes imperative for the municipal bodies to be on their toes to deal with problems like uprooting of trees during rain.

Last, but not the least, inclusive planning and affordable housing housing are fundamental if Delhi has to be transformed into a sustainable city.

Providing access to affordable housing and essential amenities for all residents usually translates into greater organic involvement of the citizenry in urban planning and daily maintenance of the public infrastructure. That can immensely improve the city’s capability in dealing with rainwater.