Why does Delhi flood every Monsoon?
Three hours of rain on Sunday -- the first heavy spell of monsoon showers -- inundated several arterial roads, underpasses, nearly a dozen hutments were washed away in a flooded drain and two people were killed in rain-related accidents.
Several areas that witnessed flooding featured in the list of 100 waterlogging-prone areas prepared by different agencies over the past few years, however, a lasting solution to the problem is yet to be found. Officials and experts blame multiplicity of agencies and the lack of a comprehensive drainage plan for the annual mess.
In 2016, the Delhi government had commissioned a study of the city’s drainage system by IIT-Delhi. Following the study, a drainage master plan was compiled which had also pointed out to the fact that the city had no single agency to manage and maintain drainage. The last drainage master plan was drafted by the Delhi government in 1976.
At least 11 agencies — PWD, the three civic bodies, Delhi Development Authority, irrigation and flood control, New Delhi Municipal Council and Delhi Cantonment Board — are responsible for de-silting of drains alongside roads under their jurisdiction, said a senior South Delhi Municipal Corporation (SDMC) official.
“With so many agencies managing stormwater drains in the city, it is difficult to coordinate and ensure that the drains are cleaned ahead of monsoon every year. Due to the multiplicity of agencies, fixing accountability is difficult. There has to be one nodal agency for cleaning and maintenance of drains in the city so that disasters such as the one that happened at Minto Bridge do not take recur,” a senior official PWD official said.
A tempo driver had drowned at the flooded Minto Bridge underpass on Sunday.
Experts agreed with the assessment, saying there should be one agency responsible for cleaning the stormwater drains and their maintenance.
Sarvagya Srivastava, former engineer-in-chief of Delhi PWD, said, “The most important thing is that the city should have a proper sewerage system in place. Currently, sewer waste flows in stormwater drains in most areas. Like earlier, there should be just one agency responsible for desilting of drains.”
Another SDMC officials also pointed out the faulty designs of the drains for stormwater flooding roads.
The official said that for instance on Najafgarh-Uttam Nagar stretch, an inadequate cross-section of roadside drains is unable to flush out water quickly from the road. “While constructing the road the PWD designed drain cross-section taking into account only roadside water but they did not calculate possible water outcome from unauthorised colonies located on both sides of the road. They should have constructed drains taking into account the whole catchment area,” the official said.
Similarly, at the Okhla underpass, the slope is such that water from all the roads accumulates in the underpass, the same official said. “Inadequate drain cross-section and gradient cannot handle heavy intensity rain. It leads to water accumulation which takes time to recede. This happens at several underpasses in the city,” he said.
Rajeev Goel, head of bridge engineering and structure at Central Road Research Institute (CSIR-CRRI), said the problem can be addressed with some design changes. “Construction of wide stormwater drain at the beginning of the slope to the underpass can help. Also, such drains where heavy water flow is expected should be connected to the main drainage. This can be done at the starting and endpoints of a flyover too. But the most important thing is to improve the drainage system along the roads,” he said.
While the Delhi PWD manages around 2,064 km length of drains along 1,260 km roads, the three civic bodies collectively manage over 520 km length of drains mainly in colonies or along roads less than 60 feet width. NDMC manages around 321 km drains while DDA manages 251 km drains.
When HT individually asked the PWD and the MCDs, officials said the shortage of workforce was one of the biggest challenges faced by them this year.
“Normally, the desilting process of big drains takes around 2.5 - 3 months. It used to begin in March. Our priority has always been to clean drains by May 31 or latest by June 15, before the arrival of monsoon in the city. But this year, most of the desilting work was completed only by the first week of July. Around 1500 labourers are engaged every year in desilting process, but this year the workforce was down by half,” a senior PWD official said on condition of anonymity.
He said that site inspections also could not be conducted on time due to the lockdown this year. The PWD manages around 2064 km length of drains along 1260km roads across 17 divisions in the city.
“We majorly rely on contract labourers. In April and May, we witnessed around 50% shortfall in the workforce. Contractors were unable to bring labourers as they had gone to their home towns due to the coronavirus outbreak. Many of those who had gone to their villages in Uttar Pradesh and Bihar to celebrate Holi had refused to return. Hence, getting labourers for the desilting process in April and May was a tough task. It was only by June that the project gained momentum when we got an adequate workforce,” the official said.