Waterlogging woes continue as Delhi relies on 1976 master plan
As both the Bharatiya Janata Party (BJP) and the ruling Aam Aadmi Party (AAP) continue to blame each other for the death of three students in the basement of a coaching centre that was inundated following rain, at the centre of the issue is the struggling drainage network of the national capital.
On Saturday, the Pusa observatory of the India Meteorological Department (IMD), located close to the Rau’s IAS Study Circle in Old Rajinder Nagar, recorded only 26.5 mm of rainfall from 2.30 p.m. to 5:30 p.m. and 31.5 mm of rainfall between 5.30 p.m. and 8.30 p.m.
The total 58 mm of rainfall in a day is not extraordinary during the monsoon season.
One of the main reasons for the waterlogging in the city is that Delhi continues to operate on a drainage master plan made in 1976, which is capable of handling only 50 mm of rainfall.
The plan was made when the city’s population was around 60 lakh and since then, it has increased about fourfold.
Also, over the years, the concrete area too has increased. So, if earlier, a particular amount of rainfall generated 50% of run-off water and the rest was absorbed by the earth, now the run-off water will be more than 50%.
As the drainage system has not been upgraded, it is unable to handle the excess water.
Last year, after the city received 153 mm of rainfall on July 9 and 10, Chief Minister Arvind Kejriwal had said the city drainage system was “not designed to handle the unprecedented level of rain”.
However, the situation has not changed even after a year.
On June 28 this year, a record rainfall led to severe waterlogging across the city and resulted in the death of at least 11 people in rain-linked incidents, including drowning and electrocution.
According to the IMD, the city had received 228 mm of rainfall on that day, the highest for the month of June since 1936.
Moreover, multiplicity of agencies is another problem. Right now, 11 different agencies manage the city’s drainage system, resulting coordination issues.
New master plan
The Delhi government in 2011 signed a memorandum of understanding (MoU) with IIT Delhi to prepare a drainage master plan for the city. A technical expert committee was also constituted to coordinate with it.
The premier engineering institute in July 2018 submitted its final report of the master plan, including a mathematical model, which could generate solutions for waterlogging in the city.
The mathematical model was created using different types of data ranging from soil type, topography and land use to rainfall and existing stormwater drain network.
In August 2021, the technical expert committee told the Delhi government not to accept the drainage master plan, citing different issues
Officials also complained that the mathematical model was too complicated to use.
Later in 2021, the Delhi government made the Public Works Department (PWD) the nodal agency to form a drainage master plan by dividing the city into three different basins and use the IIT Delhi master plan as the base. But this also faced multiple delays.
“The tenders for all three basins have been allotted to private companies, but it will take more time for them to submit the master plans,” an official said.
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Delhi
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