How should increasingly frequent instances of urban flooding shape our approach to development?
Can the lessons learnt from the flooding of our cities be our first defence against climate change?
- Urban flooding has become much more common across the world in the last two decades due to the effects of climate change.
- Management of the problem has to begin with the drainage systems of our cities, and how equipped such systems are to deal with the intensity and increased volume of rainfall.
- Ø Challenges to effective management of drainage systems come from encroachment of wetlands, citizens’ apathy around garbage disposal, construction practices in the real estate industry, and laxity and corruption in urban administration.
- Challenges to effective management of drainage systems come from encroachment of wetlands, citizens’ apathy around garbage disposal, construction practices in the real estate industry, and laxity and corruption in urban administration.
- Technology for stormwater management must include mapping and zoning based on GIS-based satellite imagery, capacity planning of drainage systems with reference to the IDF rainfall curve, and plotting lakes and wetlands into primary, secondary, and tertiary channels of urban water conveyance.
- Valuable lessons for urban planners can be taken from the Sponge City principles that have been developed in China for the absorption and reuse of rainwater in cities like Shanghai.
Any average urban Indian in 2025 does not need the Intergovernmental Panel on Climate Change (IPCC) reports, the Lancet Countdown, or the WMO State of Climate Services report to tell them about increasing instances of urban flooding. Every year, we have more widespread, visible and critical episodes of urban flooding that cripple infrastructure and cause great harm to homes and workspaces. The lives of thousands of people are affected, in addition to the deaths and casualties reported from flood-related accidents.
Of course, it is not as if urban flooding is only a few decades old. As a person whose childhood in the 1970s and 80s in Mumbai was gifted with at least one or two “rain holidays” in July, I was still struck by the impact of the flooding on 26th July, 2005, when high tide in the Arabian sea, and 944mm of rainfall left thousands of people marooned miles away from their homes. On that day, cars were floating on roads, and flyovers had become parking lots for cars, with people huddled in them, sheltering from the swirling waters below.
Urban flooding – a global phenomenon
Since that day, flooding has hit New York (2012), and flooding in September 2024 covered a large part of Europe. This included Spain, Austria, where a dozen dams were breached, the Czech Republic, Croatia, Germany, Hungary, Italy, Poland, Romania, and Slovakia. Extreme climate events are forcing countries across the world to look at ways to prevent urban flooding, earlier reported regularly only from a low-lying country like Bangladesh or a riverside city like Shanghai.
When we look at how gleaming models of development in our country, like the IT hubs of Bengaluru and Gurugram, get submerged every year during the rainy season, the problem acquires a different character. It is evident that, even when modern buildings and offices are being planned, less attention has been given to the environment that is meant to support them.
Drains as definers of urban planning
The draining of water during periods of intense rain is the most important element of urban flood management. Since those days of my childhood in 1970s Mumbai, the subject of whether the stormwater drains of the city had been cleaned and dredged thoroughly from the months of March to May, to prepare for the monsoon’s arrival in June, used to make headlines in the newspapers. Was the BMC sufficiently prepared? This was very much a part of the public discourse.
What the 2015 floods of Mumbai showed, however, was that stormwater drains that were over a century old, and covered only a small area of the city, were inadequate to deal with the immense volume of water within a period of a few hours. They also highlighted the many other factors that contribute to flooding:
- waste clogging natural drainage channels,
- reduced seepage of water on the increasingly impervious soil in cities due to the use of non-porous construction materials,
- encroachment on lakes and natural water bodies within urban areas,
- and lax implementation of regulatory mechanisms like the Environment Impact Assessment or EIA.
Urban geographer and political ecologist Malini Ranganathan, who has closely studied the flood risks in post-colonial Bangalore, found the draining of water to be a complex web of what were marked on maps, “… as “rivers”, “irrigation canals”, “raja kaluves” (large drains), “katcha (unfinished) drains”, “sanitary drains”, “box drains”, and even “roads” and “residential layouts”.” What makes her findings significant is being able to see drains as central to the city in the form of assemblages of fixity (social orders, state forms, intransigent discourses, settlements, solid waste) and flow (irrigation water, stormwater, sewage, capital). As she puts it, “… in the new millennium, flood risk is the product of an intensifying alignment between storm drains and the flow/fixity of real estate capital. Specifically, the dizzying flow of speculative and global real estate capital through Bangalore’s storm drains and the fixity of resulting informal developments in wetlands have rendered the flow of stormwater especially unpredictable and risky.”
As was proved in the floods of September 2022, the flow of rainwater was so intense that it dwarfed the fixity of a gated community of villas in Bellandur, where billionaires live in homes costing Rs. 10 crores and above. Many were evacuated in boats, and expensive German and Italian cars were submerged in water and silt. Where could the water have gone if it had no egress? A lot of this development had happened on what used to be Bellandur Lake.
A need to prioritize rivers
In estuarine cities like Mumbai, where water from the Dahisar, Poisar, Mithi and Oshiwara rivers flows into the Arabian Sea via many small creeks, or Chennai, where the Adyar and Cooum rivers flow into the Bay of Bengal, sediment from upstream areas during monsoons in the swollen rivers places an additional strain on drains in the urban areas. Unfortunately, the polluted state of these rivers and their neglect over decades has only compounded the problem.
It is not only the mighty Ganga that remains as a symbol of our failure to address the continuing pollution and neglect of rivers. In all our cities, rivers that should have been a healthy habitat for many species of flora and fauna, that could have been used as a means of transport for goods and people have been reduced to the status of nullahs or carriers of sewage. The foaming waters of the Yamuna in Delhi make headlines each year.
One of the fundamental factors that proves to be a hurdle in taking up the cleaning, maintaining and preservation of our rivers is our accepting their degraded status as normal. This has been called out by Prof. P.H Kahn, director of the Human Interaction with Nature and Technological Systems (HINTS) Lab at the University of Washington. He refers to “environmental generational amnesia,” an acceptance of environmentally degraded settings that prevents us from envisioning or executing the reversing of environmental harm.
With the youth of our cities lacking stories from their elders of how they were able to swim, boat, or bathe in the rivers in our cities, this generational amnesia is affecting our policies for the future. In contrast to this, young Indians who go abroad to study, or visit cities in Europe, Japan, Canada or other countries find that rivers can retain their role in the hydrological cycle and enrich the lives of city dwellers. There is an urgent need to prioritize rivers and work for their health, not just to develop riverfronts as tourist attractions.
Pointers for stormwater management
So, do we have to stay trapped in this cycle of urban flooding caused by ancient, inadequate or neglected stormwater drains, and the rapacious encroachment of wetlands in urban areas by both, haphazard construction of slum dwellings, or gleaming towers of builders/developers?
In fact, we have the necessary knowledge for urban planners to address all these issues if they have the intent, and successive governments stay determined to improve living conditions for all in the face of climate change.
Regular desilting and clearing of drains before monsoons, are crucial to prevent blockages, with pre-monsoon and post-monsoon inspections. Unfortunately, these often become a blame game between political parties depending on which party controls the municipal corporation at the time. These are in fact, very important to help identify structural issues, and must be carried out with utmost diligence.
In addition, what is a very difficult task because of the powerful vested interests that operate around construction and real estate is managing encroachments along floodplains. How to prevent the proliferation of slums, or the grabbing of large tracts of land by builders who have obtained clearance for their projects in dubious ways is a major challenge. But this is necessary to ensure that floodplain areas remain free of construction.
Emulating best practices for the future
Apart from the challenges posed by our immediate infrastructure, and the mindset of indifference we must take note of what is being done in other countries to mitigate the risks and damages from urban flooding. For instance, Shanghai in China has been taken up as a pilot for the concept of a Sponge City. This translates into making the city capable of absorbing and reusing 70% of rainwater.
Transforming our own cities into such sponge cities would need immediate measures that have had demonstrable results across the globe.
Shanghai’s transformation has been marked by such greening of public spaces. “To mitigate urban flooding, cities must adopt flood-resilient infrastructure policies and implement Sponge City principles, which promote permeable surfaces, rainwater harvesting, and urban greenery. Additionally, retention basins and flood buffer zones should be developed to temporarily store excess water, reducing the risk of sudden flooding.”
While retention basins temporarily hold excess stormwater and allow it to infiltrate gradually into the ground, detention basins can store water and release it at a controlled rate after the intensity of the rains has lessened. Both these are part of the design of large storm drainage systems. Buffer zones are created when grass, shrubs and green ground cover helps to reduce the erosion of soil from stormwater runoffs.
What must drive us towards better policies and management of all the above, are the high socio-economic costs we are paying during repetitive instances of urban flooding. Can we afford the stagnation of the local economy, the many health hazards, and crippled infrastructure that comes in the wake of each episode of urban flooding?
In a strangely ironic way, the Manyata Tech Park waterfalls of October 2024 fell into the trench of a building under construction that accidentally served as a retention basin. But for present and future generations of urban Indians, addressing the issue of urban flooding has to be much more thoughtful and focused.
References
- Ranganathan-2015-Antipode.pdf
- Billionaires-in-boats-as-flooded-houses-in-elite-bengaluru-locality-lose-light-water
- Shanghai unveils plan to enhance urban resilience with sponge city initiatives
- preventing-flooding-and-erosion-with-proper-storm-drainage-systems
- environment/the-forgotten-water-ecosystems-of-mumbai-84732
Scharada Dubey
About Author
Scharada Dubey is an author of narrative non-fiction and children’s books. ‘Portraits from Ayodhya: Living India’s Contradictions’ (2010) and ‘M for Minority: Muslims in #NewIndia’ (2020) are among the books she has written on contemporary India. She also works on writing partner projects, and connects with listeners through her show ‘Yes, Aunty! The Scharada Dubey Podcast’. Scharada lives and works in Bangalore.