Even 4mm to 5mm of rain in Delhi’s Chhatarpur and adjoining areas causes a flooding in Gurgaon, particularly along the foothills of the Aravallis, as the natural gradient between the two areas differs by almost 10 metres.
Before urbanisation in the 80s, water from Gurgaon-Chhatarpur area and the Gurgaon-Faridabad belt was channelised using a series of bundhs that were fed by natural ravines, drains and minor channels.
This system of rainwater management, pioneered by the British, however, has been laid to waste by indiscriminate construction across the city.
Water channels, ravines and natural drains, which connected the bundhs, have been blocked, encroached and build upon during the last two decades of realty boom.
While the city has grown by leaps and bounds, the natural drainage system, vegetation and groundwater system have been damaged almost beyond redemption.
Bhawani Shanker Tripathy, a social activist and one of the members of Mission Gurgaon development, says permission to change land use across Gurgaon without taking into account the natural drainage pattern has led to the present crisis.
“The city does not have an integrated drainage system and the passage of natural drains has been blocked at many places,” he said. Gurgaon and the adjoining areas witness an annual rainfall of 600mm to 650mm and the water flows from the Aravallis in the east to the Najafgarh drain in the west.
The encroachment in the Aravallis, destruction of natural nullahs, dumping of debris in hills and massive construction in the foothills have ensured that even a minor rainfall leads to flooding in Gurgaon. While earlier, there were four defined natural drains that ensured the flow of water into the Najafgarh drain, the city now depends on three major drains that are partially channelized and partially blocked leading to frequent waterlogging.
“The major reason for waterlogging is that around 100 bundhs in Gurgaon and Mewat, which had the capacity to hold more than 2 lakh acre-feet of water, have been destroyed. Every Gurgaon village had two ponds. These only exist on paper now,” said Latika Thukral, who heads IAmGurgaon, an NGO.
At present, the bulk of rainwater from Sikanderpur to Badshahpur flows to the Najafgarh drain via Leg 1 drain, Leg 2 drain, Khost Nullah and Badhshapur drain. All these drains form the master stormwater drain network of Huda but, till this year, these were blocked, choked and silted.
“Almost 70% of the city suffered from waterlogging because the drains have not been cleaned for almost three decades. The concreting of drains will further lead to problems as water, which took 3 to 4 hours to reach Hero Honda Chowk, only takes 15 minutes now,” said Pradeep Kumar, superintending engineer, who was serving in MCG on deputation.
It was only when the grave problem of desilting the drains was flagged during a high-level meeting that the Huda, the MCG and other departments finally swung into action.
Huda administrator Yashpal Yadav said they have five super sucker machines to clean the drain. “We have cleaned the Bajghera section in particular. Leg 2 at Dharampur and Badshahpur drain has been de-silted. This year, the situation will improve,” he said.
Given the grave threat posed by regular waterlogging in the city, the government is looking at a more holistic solution.
“We are going to build a robust drainage system after mapping the natural drainage system of the Gurgaon subregion,” said MCG commissioner TL Satyaprakash.