From Gurgaon to Chicago, a global wake-up call on floods

More cities are flooding under heavy rains, but drainage, zoning, and warning systems lag far behind.

Vaishnavi Chandrasekar

Pic credit: Wikimedia Commons

This is a summer of floods. 

That’s been especially evident in the US. In the state of Texas, a combination of two tropical storms created a system that produced 10 to 18 inches of rain over the Guadalupe River basin early July, causing flash floods that took at least 131 lives. (According to one report, the river rose from 3 feet to 34 feet in 90 minutes.)  A few days later, Chicago saw a rare extreme rain dump that sent 5 inches of rain in five hours. And in New York, subways were flooded by the city’s second-heaviest one-hour rainfall. 

On the other side of the world, torrential rains in Pakistan since late June have taken at least 200 lives and damaged 700 homes. In China, heavy downpours caused landslides and a river burst its banks in the central provinces, forcing evacuations of thousands of people. And in India, heavy rainfall inundated parts of Delhi, Gurgaon, and Hyderabad. 

These disasters highlight the need to improve forecasting and early warning systems for rain and flood, even in so-called developed countries. But they also underscore the slowness of governments at both local and national levels to make some tough decisions to reduce the impacts of extreme rain.

Data suggests heavy rain events are on the rise. After rains in Botswana killed at least 30 people in February, a study by the World Weather Attribution—a team of international scientists that look at extreme weather events—found that five-day heavy rainfall events in southern Botswana had increased by 60% since preindustrial times.  In the UK, one assessment found the number of months in which districts received twice their average rainfall has risen by 50% in the last 20 years. 

Global warming is a driver. When temperatures rise, more water evaporates from land and sea, adding more moisture in the air. Every 1degree Celsius rise in temperature increases the atmosphere’s moisture-holding capacity by 7%. 

And in Nepal and other high Himalayan regions, warmer temperatures can lead to glacial lake melt and bursts, releasing vast quantities of water downstream. On July 7, a glacial lake burst in China led to flooding in Nepal’s Rasuwa district, killing at least 11 people and washing away a critical bridge.  Experts expect a three-fold increase in risk of glacial lake bursts in the Himalayas in the coming century

Among disasters, floods consistently exact some of the highest human and financial tolls: Water-related hazards accounted for 50% of all disasters and 45% of all reported deaths between 1970 and 2019, according to the United Nations Office for Disaster Risk Reduction. The number of people exposed to floods globally rose in the same period, from 28.1 million in 1970 to 35.1 million in 2020.

The financial costs are also high. According to insurer Munich Re, natural disasters caused losses of US$320 billion in 2024, of which around US$140 billion were insured. Local governments are often the hardest hit: In the UK, for instance, flood clean-up and recovery costs local councils up to £566 million every year, according to one report. With council budgets shrinking, “a single major event could wipe out more than 16% of a council’s entire yearly budget for flood recovery,” said the report.

Asia is particularly vulnerable, with its high populations, monsoons, and urbanisation. In India, more than 17,000 people died between 2012 and 2021 due to floods and rain, according to government data. Floods have also become more common in the northeast, and Bihar and Uttar Pradesh, leading to migration to other states and cities.

To tackle flooding disasters, India and other countries—as well as global bodies—are pushing to expand early warning systems. Half of all countries have implemented such systems so far, and the UN wants universal coverage by end 2027. Early warning systems are also a priority for the G-20 grouping of African, Asian, and South American countries.  

Such systems are especially important for flash floods. These account for most flood-related fatalities but are notoriously hard to predict in sufficient time. Even in Texas, USA, which has a history of riverine floods and a warning system in place, the alerts failed to reach a children’s camp in the mountains. The weather service issued a flash flood watch 12 hours in advance of the event, upgraded it to a warning three hours ahead, and then declared an emergency. But the alerts didn’t reach everyone as they happened overnight—the flooding and alerts happened overnight, when people were asleep, and the remote camping area lacked sirens, reports say. 

Beyond warnings and forecasts, some countries have tried to use insurance to reduce costs of recovery. However, a Financial Times report suggests that the market appetite to cover disaster risks might shrink if events rise. The head of Flood Re, UK’s national flood insurer, told FT they would likely raise premiums further as “we are getting to the limits of what global reinsurance markets can cope with”. Flood Re was set up by the UK government in 2016 as a temporary solution while the country builds better flood defences and risk zoning. But that hasn’t happened, and the re-insurer said its costs have surged by about £100mn in just three years. 

This brings us to the choices local governments must make. 

In growing economies like India, development of infrastructure and cities is proceeding at a rapid pace without sufficient guard rails to prevent climate disasters like floods. That was evident a few weeks ago in Gurgaon, a relatively new city near New Delhi, that was submerged by overnight rainfall that overwhelmed its drainage capacity.  

The city doesn’t get as much rain as many others—600mm a year on average compared to over 2000mm in Mumbai. Yet, it gets waterlogged almost every monsoon. The reason is not far to seek as the city expanded across former farmland, it built against the natural drainage flows and over existing channels—60 canals were reduced to four. The growth has been haphazard and piecemeal, with no real plan in place. Some areas don’t even have storm water drains; run off ends in narrow sewer lines. (As one Golf Course Road resident exclaimed on social media: ‘Rs 100 crore homes, no drainage.’)

Even cities used to intense monsoon rain struggle. Mumbai’s storm drain capacity was recently doubled—from a capacity of 25mm an hour to 55mm an hour—but that’s far below what’s needed for the rising number of 100mm rainfall days. The National Disaster Management Authority is now funding urban flood mitigation in many cities, including expansions in drainage and installation of early warning systems. 

Such infrastructure will likely come—after all, it involves funding visible projects and awarding contracts. What remains less certain is the government’s willingness to restrain building: to keep high-risk land free of construction, especially floodplains and coastal zones that could act as natural buffers for river rise and storm surge. 

One overdue step would be to map urban land for flood risk and publish those maps--letting markets reflect that risk. Properties in high-risk zones would naturally become costlier to develop or sell. But this kind of zoning and transparency remains absent in most Indian cities, including Mumbai.

Still, some cities are starting to think about “nature-based solutions”. Chennai and Ahmedabad are planning a string of “sponge parks”, inspired by China’s ‘sponge city’ program and aided by the NDMA. These open spaces are designed to retain water through permeable surfaces, drains, or underground tanks. They’re not silver bullets—but they’re an important first step. 

India's drought-prone area has increased by 57 % since 1997, while instances of heavy rainfall have risen by almost 85 % since 2012, according to the World Bank

About one in three people in India, have either already moved or considered moving because of weather-related disasters such as extreme heat, droughts, sea-level rise, flooding, or others, according to the Yale Program on Climate Change Communication

Floods and flash floods claim thousands of lives each year and cause billions of dollars in damage, the United Nations said on July 21, 2025.

A 2022 World Bank study estimated that 1.81 billion people – nearly a quarter of the world’s population – are directly exposed to 1-in-100-year flood events, with 89 per cent living in low- and middle-income countries, according to the United Nations. 

Flash flooding in western Nigeria in June left more than 150 dead and 3,000 people displaced – more than half of whom were children. Scores of people were displaced in northeast Nigeria in September 2024 after a dam collapsed during a heavy rain spell, according to the United Nations.

More than 215 people, including 35 children, lost their lives, with dozens still missing after heavy rains triggered flash floods and landslides across Nepal, according to the United Nations.

Unprecedented flooding and windstorms impacted more than half a million people in Yemen in September 2024, the United Nations recorded.

Earth Shifts, a monthly column on The Migration Story, will analyse the impact of global green goals amid mounting climate uncertainties on lives and livelihoods. 

Vaishnavi Chandrashekhar is an environment and science journalist based in Mumbai.