Delhi floods: Is climate change or poor drainage to blame?

Ever wondered why just a couple of hours of rain leads to massive traffic snarls in Delhi-NCR? Can rising natural devastation only be attributed to climate change? 

Delhi is once again recovering from a severe flood threat as the Yamuna’s water levels touched 207.48 metres, 0.01 metres below the 1978 flood level. This also comes just two years after Yamuna had reached a historic danger level of 208.66 metres. 

While some have blamed the water released from the Hathnikund barrage in Haryana, others have attributed it to the wettest August Delhi has faced since 2010. But why is the capital city becoming increasingly vulnerable to rain and flooding? 

Understanding Delhi’s landscape

While it is true that climate change is causing more erratic rain patterns, Delhi also suffers from an outdated drainage system and an inefficient system to manage it. 

Delhi’s topography is largely flat, comprised of two main features:

• The Delhi Ridge, part of the Aravallis, acts as a natural watershed.

• The Yamuna River, which stretches 55 km through Delhi, supplies water to 70 percent of its residents.

Ironically, though only two percent of the Yamuna’s total length flows through Delhi, the city contributes nearly 80 percent of the river’s pollution. 

Three barrages, namely Wazirabad, ITO, and Okhla, control the river’s waters, while the Hathnikund barrage in Haryana determines how much water enters the city.

A flood warning was issued in Delhi on September 1 by the Irrigation and Flood Control (I&FC) Department after discharge from the Hathnikund barrage rose to over 3.22 lakh cusecs – the highest this season.

Bhim Singh Rawat of the South Asia Network of Dams, Rivers and People (SANDRP), while speaking to Newslaundry, highlighted that in comparison to 1978, when 7 lakh cusecs of water were released, Hathnikund’s release was half the amount and should not have caused this. He pointed out the decrease in the Yamuna’s carrying capacity and blamed the government for letting encroachments take place. 

A broken drainage system

Delhi’s last drainage master plan was drafted in 1976, when the city’s population and urbanised area were much smaller than it is today. Its network can only handle 50 mm of rainfall per day, far below what heavy monsoons can bring.

The key challenges are:

• Combined sewer system: Stormwater and sewage mostly run in the same pipes, leading to blockages and waterlogging.

• Encroachments: Unauthorised colonies, settlements, and even government projects such as the once controversial Commonwealth Games Village, block natural water flow. 

• Fragmented responsibility: Multiple agencies (Delhi Development Authority, Delhi Jal Board, Public Works Department) control different parts of the system, making accountability far-fetched.

Mammoth tasks require a strong will

In June, the Delhi government claimed it had removed 20 lakh tonnes of silt from major drains and completed 90 percent desilting. Chief Minister Rekha Gupta had even said that the capital will not flood this year. Yet, here we are. 

As per experts, the Yamuna’s carrying capacity has nearly halved, with the riverbed reportedly having risen by 7.5 feet between Wazirabad and Okhla. We spoke to landscape architect Akshay Kaul to understand some solutions and how they could be implemented. 

Kaul stressed that issues that Delhi is facing are similar across Indian cities and said, “Of the 500 to 600 lakes, only around 150 lakes remain in Delhi. All these lakes had catchment areas around them. So, the water went into these and held it for some time. There is also the Najafgarh lake, which was huge until it was turned into a conduit to take the water to the Yamuna as soon as possible.”

He added, “We had about 322 drains or rivulets, out of which they have been converted to 22 drains, and most of them are sewage drains. So, can we separate the sewage from these? In open public spaces, we can look at nature-based solutions, where we temporarily take the water. Not only will it reduce flooding, but it will also recharge and begin to make us water sufficient. The other solution is on-site detention, which cities like Sydney have very easily adopted. You slow the flow of water from your roofs, from your parking lots. They are very simple devices to install. So, you slow, you delay. But this requires a multi-stakeholder approach to achieve.”

As Delhi recovers from its 2025 flood and heads into its polluted AQI winter months, the question that remains is whether the city’s new government can summon the will to deliver urban resilience? 

Watch. 

Samarth Grover is an independent journalist based in New Delhi.

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