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Choked cities go under: DNA examines how vanishing water bodies & green spaces causing urban sprawls to sink

Rains that should help address water crisis and revive dying rivers are wreaking our poorly planned cities like never before. DNA examines how overwhelmed drainage, rapid concretisation, vanishing water bodies and green spaces are causing urban sprawls to sink, monsoon after monsoon

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On December 1, 2015, Chennai was ravaged as it received its heaviest rainfall in decades.
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In his college days, Suneel Singh romanticised with the calls of "a particular bird" that signalled joy — the monsoon was coming. "We couldn't wait to go out and get drenched," recalls the 45-year-old teacher. Baarish always influenced and inspired music, movies, art and literature. This was then. Now, it also evokes a sinking feeling. "Low-lying areas in Mumbai faced water-logging even then, but the city never had such crippling floods," says Singh.

He still craves for pakoras and hot tea when it rains. It's just that his priority now is to survive.

The June-to-September season — a lifeline for the country's agriculture and economy — mostly pours miseries in Indian cities. Rains do little in recharging groundwater and infusing life into the dying rivers, but lead to flooding that derails rail, road and air traffic, damages infrastructure and kills people. And it's a rising trend: Mumbai (2005), Surat (2006), Kolkata (2007), Hyderabad (2008), Delhi (2009 & 2010), Guwahati (2010), Srinagar (2014), Chennai (2015), Gurugram (2016) and Mumbai (2016 & 2017).

The causes are many: Poorly laid and clogged drains; badly planned urbanisation with no concern for topography; massive concretisation and destruction of floodplains, lakes, marshlands and wetlands; faulty road networks with little care for culverts; unbridled tree felling and vegetation removal; and climate change. Corrupt civic bodies that flout court orders with impunity have deepened the mess.

Drainage collapse

On August 29, Mumbai ground to a halt after it rained 315.8 mm in 12 hours. The downpour was about a third of what the city had received on July 26, 2005. The cloudburst-induced deluge and its aftermath 12 years ago had claimed about 700 lives. But nothing much was learnt. Many of the drains in India's financial capital remained choked.

Delhi's several stormwater drains have also been covered to build shops and parking lots. Others carry domestic sewage and industrial waste. Lining of drains is also causing floods. In fact, Delhi has not had a drainage master plan in four decades when its population went up by 350 per cent to 18 million. A new plan looks at fixing existing drains. But relief is not expected anytime soon. Authorities need Rs 19,500 crore and 20 years to lay 9,500 km of sewer lines to allow drains to carry only rainwater. Stopgap measures will also take three years.

Kolkata has similar problems. One of the three natural channels which carried away the city's sewage and rain has been terminated by Metro construction. This causes floods in several areas. "Gully pits are chocked with plastic and garbage… How will pumping stations work?" asks renowned ecologist Dhrubajyoti Ghosh.

Topography disregard

Several parts of Mumbai are below sea level. So, when there is high tide, accompanied by heavy rains, waterlogging is unavoidable. The real crisis is, the drainage system can deal with about 25 mm of rain per hour. Current projects are expected to double it to 50 mm. But the city often records much more rainfall and faces massive flooding.

Delhi, on its part, did well before it began growing rapidly. Historically, its residential pockets never faced waterlogging. Mehrauli, Shahjahanabad, Civil Lines, Delhi Cantonment were all built on elevated grounds that were easily drained. Urbanisation in low-lying and poorly drained areas disregarded topography in both cities.

Water bodies killed

On December 1, 2015, Chennai was ravaged as it received its heaviest rainfall in decades. A Parliamentary panel report later blamed encroachment of lakes and floodplains for the floods. According to water expert S Janakarajan, Chennai's IT corridor and other institutions got inundated in 2015 because more than 90 per cent of the city's 7,000-hectare wetlands had been destroyed over the years.

"All three rivers in Chennai — Kosasthalayar, Cooum and Adyar — are now sewage carriers, but they can still prevent flooding, provided they are de-silted and freed of encroachments," he says. There are 3,600 lakes in the two upstream districts of Tiruvallur and Kancheepuram that can hold over 100 tmcft (thousand million cubic feet) of water. "We still allowed 250 people to die, and an economic loss of Rs 20,000 crore."

Mumbai has also seen destruction. Vast swathes of floodplains, mangroves and wetlands are gone. The city's four rivers, draining rainwater into the sea, are facing massive pollution and encroachment. Environmentalist Stalin D rues that the Mithi river today has its mouth pinched.

In Delhi, the Yamuna looks like a black noxious thread during the lean season. About half of the 1,000-odd water bodies registered with the government have actually vanished. Manoj Misra of Yamuna Jiye Abhiyan says the catchments of remaining water bodies have been cut off for housing and other constructions, impeding the flow of storm-period water to them. "This is happening even today in the so-called planned manner in North Delhi," he says.

Rapid concretisation

In Delhi, most soft areas have been paved over, and plots are concretised end to end. Studies show that the amount of water that would not seep into the ground has gone up from 50 per cent to 85 per cent in recent years, causing massive flooding. Mumbai also faces inundation of roads as concrete building compounds have shrunk areas for percolation of water. Manu Bhatnagar of the Indian National Trust for Art and Cultural Heritage says cities must adopt porous paving. "There should be at least 25 per cent open area as soft green."

Road ahead

Scientists warn that flooding events will become more frequent due to climate change. The World Bank's forecast of 20 cm of sea level rise by 2050 would make Kolkata — on average, barely five metres above sea level — dangerously exposed to flooding risks. Independent environment journalist Nivedita Khandekar says the crisis is already spreading fast. "Scores of areas and streets in Hyderabad were flooded only a few days ago. Same causes."

Water expert Himanshu Thakkar says urban areas need to drastically scale up their capacity to manage rainfall and waste water. "Tidal conditions have to be kept in mind for cities such as Mumbai, Kolkata, or Chennai. Cities such as Ahmedabad, Bharuch, Cuttack or Surat need to take into account heavy upstream releases." All this has to be assessed annually, since carrying capacities of drains, rainfall and flow patterns change.

Noted water conservationist Janak Daftari demands clear demarcation of open spaces, rivers, water bodies and floodplains and their protection. "Nature has designed srishti for water to flow into the ground or a water body. We must stop making it 'stand' and wreak havoc."

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