What the Chennai floods tell us about urban planning in India

admin November 23, 2021
Updated 2021/11/23 at 3:57 PM

The northeast monsoon, which has been lurking ominously over Tamil Nadu, has dumped the most rain on a single day in the previous five years. It’s also brought up memories of the disastrous Chennai floods of 2015, a collective trauma that the city’s citizens are still recovering from.

Floods in South Asia have turned urban in the past two decades, eliminating the barriers that had previously divided city and country. Floods often occur in big cities such as Mumbai, Chennai, Dhaka, Karachi, and Kathmandu, and are accompanied by heavy rainfall. In October, buses floated along flooded highways in Hyderabad, while India’s first “greenfield” international airport in Bengaluru was inundated and reclaimed by the water it was supposed to redirect with concrete.

The IPCC’s 6th Assessment Report (AR6) was released in August of this year, while monsoon floods raged over the subcontinent. Since the 1950s, research has documented an increase in the frequency of heavy precipitation events, inferring that this is due to human-caused climate change.

If there was ever any doubt, the climate catastrophe has arrived. Extreme downpour events have become more intense and unpredictable than they have ever been. However, it only accounts for a portion of the recurrence of urban flooding. The whole narrative is entangled with land politics.

The subcontinent’s cities are all waterscapes. They are crisscrossed by rivers, dotted with marshes and springs, and rest atop unseen aquifers. Our cities, however, are designed to dominate water rather than live with it, motivated by a need for more land. Urban drainage is also harmed by this land-centric mindset.

The term drainage comes from the Old English word dreahnian, which originally meant “to strain out of a liquid.” If urban drainage were to live up to its etymology, it would transform cities into sieves that let water soak and flow through. This necessitated protecting the city’s many natural watercourses, which drain water and support vulnerable groundwater aquifers. These rivers, dubbed nullahs, or natural storm drains, have been sacrificed on the altar of land-centric urban development.

Gubbi Labs, a Bengaluru-based research group, discovered in 2014 that 376 kilometres of natural storm drains have vanished from the heart of India’s Silicon Valley, thanks to geospatial photography.

The National Green Tribunal of India established a committee in 2015 to investigate the state of natural stormwater drains in Delhi. 44 of the 201 “drains” documented in 1976 were discovered to be “missing” upon scrutiny.

These “lost” rivers were either encroached upon and built over, or they were linked to sewer drains in both situations. The Indian government’s current fixation with resurrecting historic rivers contrasts sharply with its disinterest in repairing vanishing urban streams.

Urban floods are exacerbated by poor design and corruption, which are inextricably linked to South Asian urban development. Consider the construction of stormwater drains. The size of their outputs should be determined by the amount of rainfall (in millimetres per hour) and the peak flow through the drains. Most South Asian nations, on the other hand, either lack design requirements or have outlets that are too narrow to handle peak flow. Stormwater drains from real-estate sites, for example, are diverted into important roadways in some sections of Karachi. It’s no wonder, therefore, that above-average rainfall results in flooded areas.

Similarly, open areas, wetlands, and floodplains have been ruthlessly built over in violation of environmental rules and municipal bylaws, rendering cities impervious and unfriendly to precipitation. Residential houses have been constructed atop stormwater drains in practically every city in South Asia. The breadth of drains in Karachi has been decreased from 200 feet to 20 feet as a result of this encroachment.

Unfortunately, encroachments are often blamed on the urban poor, who live in perilous conditions in low-lying drainage regions due to a lack of affordable housing. Following the deadly Chennai floods of 2015, experts pointed out that the state government of Tamil Nadu was the greatest encroacher of urban waterways and wetlands, having created runways, bus terminals, and IT parks by paving over water bodies.

Rainfall in a changing environment no longer finds its way to underground capillaries or surface water bodies because concretisation has become shorthand for development. Massive amounts of water are being channelled towards drainage networks that are either “missing” or clogged with trash, sewage, and solid waste after strong, short-duration rains. Whatever water does make it to the closest river, it finds the bank has been turned into real estate and the riverbed has been heavily mined for sand.

When it comes to floods, the political approach has always been to blame the heavens. Floods were attributed to “erratic” monsoons and “unruly” rivers. As a result, millions of tonnes of concrete have been and are still being poured into dams, embankments, culverts, and sea barriers. Surprisingly, when South Asian towns became impenetrable concrete lumps, they drew floods closer to home.

We must shift away from land-centric urbanisation and see cities as waterscapes in order to cure the hydrophobia that has formed our urban experience. Returning urban rivers to their floodplains will allow them to breathe again. Even though a restored lake or recovered canal is good, it is no longer sufficient. The whole urban watershed must be healed, which will require less concrete and more democracy and science at the grassroots.


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