Why do Indian cities flood every year?

Urban flooding is becoming a regular affair in some city or the other in India. Mumbai in 2005, Surat in 2006, Kolkata in 2007, Delhi in 2009 and 2023, Chennai in 2015, Hyderabad in 2020, and Bengaluru in 2022—most of the big cities faced the floods and their side effects. Who to blame? It is becoming fancy to blame climate change for every natural disaster, but there is more to it. Cities need to strengthen their stormwater drainage network, put a stop to encroachment on wetlands, natural waterways, and intensify their action to adapt to changing climate for saving lives and preventing the loss of property and urban assets

India has been hit particularly hard by flooding in many of its towns and cities, with floods causing widespread damage to both property and human life. To effectively manage urban flooding in India, city leaders need to change the way they look at the problem. Floods, natural disasters, have been occurring since time immemorial. The reason could be an overall change in climatic conditions, but the lack of or the poor quality of drainage systems and sewage networks in many of the cities make things worse. Almost every year, these floods cause loss of lives, productivity, and damage to public and personal property. The ADB report says that floods account for more than half of climate-related disasters in India, and over 54 billion USD was lost between 1990-2017.

Connections: Climate change and heavy rains

There is no denying the fact that climate is changing. Climate change refers to the long-term changes in temperature, precipitation patterns, and weather events, primarily caused by the emission of greenhouse gases over centuries. Understanding this connection is essential for developing effective adaptation and mitigation strategies to safeguard vulnerable communities and infrastructure in different regions.

On one hand, this July has been a real scorcher, bringing some of the hottest days and weeks the world has seen in centuries! But along with the heat, devastating extreme weather events have been wreaking havoc in different parts of the globe. In Himachal Pradesh, flash floods have tragically taken dozens of lives and displaced thousands more. And it’s not just there; floods have caused chaos in Uttarakhand, Delhi, Haryana, and Uttar Pradesh too. It’s crystal clear that climate change is no longer a distant threat; it’s very real, and it’s hitting us hard.

Every region in the world is facing the negative effects of climate change in some way or the other. Indian hilly states of Uttarakhand and Himachal Pradesh are facing problems because of the intensified and more concentrated heavy rainfall in a short span, and thus flooding and damage to public infrastructure and loss of lives. In these regions, the impact of flooding becomes particularly severe due to the complex terrain and the concentration of population and infrastructure in narrow valleys, river basins, and other disaster-prone areas. Here one must carefully evaluate the potential impacts of new infrastructure, particularly due to the fragile ecology of the Himalayan region. Not just these cities, Mumbai, Patna, Chennai, Bengaluru, Gurugram, Hyderabad, and many cities of the North-eastern region have suffered losses because of the floods.

It is essential to acknowledge that the effects of climate change will only intensify in the future. Therefore, a long-term approach to managing urban flooding is critical, and investment in sustainable and resilient solutions is necessary.

Upgrade drainage infra

It is a no-brainer that every city needs to cut down its GHG emissions. It is also essential to prioritize infrastructure improvements, such as drainage systems and sewage networks. Many of India’s cities have outdated infrastructure that cannot cope with heavy rainfall and flooding, exacerbating the problem. Additionally, efforts must be made to reduce the amount of impermeable surfaces in urban areas. This means removing concrete and other materials that prevent water from soaking into the ground. By increasing the amount of permeable surfaces, such as green spaces and parks, the impact of urban flooding can be mitigated. This year we saw water flooding on the road near Red Fort in Delhi. There are many old photographs of the city in which the Yamuna River can be seen flowing in the same area. Overtime, the land was used for building roads and concretization was done, obstructing the natural flow of the water. The same is the case in many Indian cities.

According to the National Disaster Management Authority (NDMA), “urban flooding is significantly different from rural flooding as urbanization leads to developed catchments, which increases the flood peaks from 1.8 to 8 times and flood volumes by up to 6 times. Consequently, flooding occurs very quickly due to faster flow times.” The authority highlights that stormwater drainage systems in the past were designed for rainfall intensity of 12 – 20 mm. These capacities have been getting very easily overwhelmed whenever rainfall of higher intensity has been experienced. But, for example, Mumbai, on average, witnesses about 800+ mm rainfall in July while London’s annual average rainfall is just 600 mm.

Another important step is to address unplanned urban development. Many Indian cities have expanded rapidly in recent years without considering the impact on the environment and infrastructure. No one can forget what happened in Uttarakhand in 2013. The flash floods followed by a cloud burst wreaked havoc and killed over 6,000 people. The unplanned development alongside riverbanks and risky areas added to the problem. Many cities have turned a blind eye to such development and encroachments. As a result, many areas are now at high risk of flooding due to the construction of buildings and roads in areas that were once natural drainage systems. Alongside is the chronic problem of waste disposal, including demolition waste, into rivers, streams and natural waterways obstructing flow and causing flooding.

To combat this, sustainable urban planning is needed, taking into account the impact of development on the environment and infrastructure and ensuring new construction is designed to be resilient to flooding and other climate-related risks. Managing urban flooding in India requires a comprehensive approach, including infrastructure improvement, reducing impermeable surfaces, addressing unplanned urban development, toning up governance, and taking a long-term approach to climate change. By implementing these measures, we can mitigate the devastating effects of flooding and secure a sustainable future for Indian cities.

The ADB report says that floods account for more than half of climate-related disasters in India, and over 54 billion USD was lost between 1990-2017. Mumbai, Patna, Chennai, Bengaluru, Gurugram, Hyderabad, and many cities of the North-eastern region have suffered losses because of the floods. It is essential to acknowledge that the effects of climate change will only intensify in the future. Therefore, a long-term approach to managing urban flooding is critical, and investment in sustainable and resilient solutions is necessary