BackWhy are our cities struggling to deal with rain?
Rainwater harvesting bye-laws should aim for a return to the original hydrological cycle says an expert
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New Delhi: Roads around Sansad Marg in New Delhi are not waterlogged. There are no flooded roads, no frustrated citizenry raging on Twitter or TV channels competing for visuals. “There is no waterlogging in the New Delhi Municipal Council area", assures Anant Kumar, chief engineer, Civil Engineering Department, NDMC. He says the NDMC area was waterlogged once, but that was in 2013, and only because the drains of the adjoining Municipal Corporation of Delhi were blocked. He begins to list, counting on his fingers, “Public Works Department, Flood Control Department, Delhi Development Authority, Delhi State Industrial and Infrastructural Development Corporation Ltd, Delhi Cantonment Board…" This is a partial list of city-level institutions grappling with one problematic resource – water.
Meanwhile, roads of Bengaluru, Gurugram and Mumbai are flooded. Mainstream news media is similarly inundated with images of blocked roads, submerged cars, people trying to cross roads in knee-deep water. There is a palpable sense of emergency and exasperation that is at complete odds with the composure of municipal officials in Delhi and Bengaluru. “We have set up control rooms in affected areas. All ward and zonal level officials are present in such areas with equipment to ensure we can address the situation. Areas like Yelahanka, and South Bangalore had water logging last year but there is none this year", says Sarfaraz Khan, joint commissioner (Health, Storm Water Drains), Bruhat Bengaluru Mahanagara Palike (BBMP).
Though civilizations have historically flourished around water bodies, cities today struggle to deal with water — its presence, absence, and excess. Traffic jams and overflowing roads are visible and immediate problems that demand an equally immediate response, but they are also symptoms of a wider, inter-connected set of issues that confront Indian cities.
What causes such persistent waterlogging in urban areas?
When it rains, the water that is not absorbed by the soil and which flows into natural and man-made drains is called run-off. “Run-off in an unoccupied site typically comprises 10-15% of the rainwater. When something is built on the site, like a house, the run-off increases to 90-95%", explains S. Vishwanath, director of Biome Environmental Solutions, a Bangalore-based design firm focused on ecology, architecture and water. Increasing built-up area in cities and concrete as the building material of choice ensure the reduction in the amount of runoff that might have been otherwise absorbed by the soil. Conventional storm-water management in cities bank on sewerage networks designed to drain this run-off from city surfaces.
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However, storm-water drains in cities face the issue of being clogged because of silting, accumulation of non-biodegradable wastes and construction debris. Before the monsoons begin every year, it is standard practice for municipal bodies like BBMP and NDMC to carry out desilting and cleaning of the stormwater drains. The report by the team dispatched to ascertain the cause of waterlogging in Gurugram found that the three drains (Bajghera, Dharampur, and Badshahpur) that would divert water away from the city were “under construction". Water was being diverted through smaller drains, whose capacity did not suffice during the rains.
Of more concern is the blocking of natural drainage pathways through construction activity and encroachment on catchment areas, riverbeds and lakebeds. Urban flooding in Chennai in 2015 was exacerbated by the rampant construction along natural drainage courses such as the Pallikaranai marshlands and the floodplains of the River Adyar, leading to the retention of water meant to be drained out. “After we got the intimation from the IMD, our revenue department conducted a survey of all storm water drains. We found over 1500 illegal encroachments and so far we have demolished almost 800 such encroachments", says N. Manjunath Prasad, Commissioner, BBMP. But what about the fact that the ever-crowded and ever-flooded Majestic bus station in Bengaluru stands shakily on the Dharmambudhi lakebed? Or that the Mass Rapid Transit System in Chennai has been built over the Buckingham Canal?
A blindspot in urban planning
If urban transport infrastructure is the first to be hit during the rains, it is also because urban mobility has been very close to the heart of urban design. S. Vishwanath points out that the impetus for urban planning has been to reduce the distance between work and residence, to the blindness of something as critical as water. Transport infrastructure such as roads and expressways has exacted a toll on a city’s natural capacity to deal with water. “Urban planning has to necessarily take into account water in all its forms, whether it is piped water supply, rainwater, stormwater, surface water or groundwater", he says.
Also Read: How relentless showers forced Gurgaon to a grinding halt
Then there is the fact of rain itself. The Fifth Assessment Report (2014) of the Intergovernmental Panel on Climate Change projects an increase in extreme weather events, which includes a decrease in the total number of rainy days and an increase in the amount of rainfall received per day. This is exceptionally relevant for the design of sewerage drains in cities. “Drainage systems are designed for 25ml/hr of rainfall. But if in a short period, there is an unprecedented amount of rainfall, it overruns drainage capacity. At the same time, it would be extremely cost-intensive to change the design of the drains just to accommodate a few hours of heavy rain", says Anant Kumar.
But why does the word ‘unprecedented’ find its way into explanations around rainfall when the Indian Meteorological Department puts out daily and weekly weather forecasts? The Karnataka State Natural Disaster Monitoring Centre operates around 80 weather stations in Bengaluru, capable of yielding granular ward-level data on precipitation and temperature. Moreover, the municipal officials are aware of the locations that are prone to waterlogging as they are required to install pumps in these areas as a pre-Monsoon precaution. Why does this information that is evidently available not translate into preparatory action?
The question brings back Kumar’s list of institutions mentioned in the beginning of this article, pointing towards a fragmented multiplicity of institutions and a lack of institutional coordination. Disaster-preparedness, accountability and transparency are the first casualties, which eventually translates into the buck being passed around ad nauseam amid civic uproar. “There is a stringent need for an integrated urban water management institution that can translate data into plans, and the plans into actions. Rainwater harvesting bye-laws should aim for a return to the original hydrological cycle", says Vishwanath, arguing for a holistic treatment of water management from the scale of the household to that of the river-basin.
Roads around Sansad Marg in New Delhi might not be waterlogged this time, but it wouldn’t take much for that to change.
Pretika Khanna from New Delhi, Nidheesh M.K and Sharan Poovanna from Bengaluru contributed to the story.
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