Delhi set to get new drainage plan in 15 days: PWD

After assessing the draft, work will be commenced to revamp the drainage system of the Capital that was laid over 50 years ago.

A draft of the new drainage master plan for Delhi will be ready in the next 15 days, Public Works Department (PWD) minister Parvesh Verma said on Saturday, adding that survey reports and suggestions from consultants appointed a year ago will be incorporated in the draft.

Delhi PWD minister Parvesh Verma (RAJ K RAJ /HT PHOTO)

After assessing the draft, work will be commenced to revamp the drainage system of the Capital that was laid over 50 years ago. “We have received the report for the Najafgarh basin while reports on Barapullah and Trans-Yamuna basins will also be submitted in about 15 days. After we have all three reports, we will start the work on revamping the drainage network of Delhi. We have seen that drains are in dire need for repair and upgrade. We will start with the priority areas where urgent interventions are needed,” said Verma.

Notably, Delhi primarily has three large drainage basins — Najafgarh, Trans-Yamuna, and Barapullah.

The drainage master plan has remained long overdue as it was last prepared in 1976. A new plan was initially proposed in 2009, but has not seen any progress as yet.

In May 2023, the PWD finally appointed a consultant for making a drainage master plan for Delhi’s Najafgarh basin — largest of the three basins. The consultant was given one year to complete the project, which has recently been submitted. Officials said that based on the recommendations by the consultants, PWD will check the feasibility and prepare estimates, which will then be sent to the government for approval before work begins.

Bids were also floated to appoint consultants for the other two basins — Trans-Yamuna and Barapullah — about six months later. “Meanwhile, if there are smaller, local suggestions, we will try to implement those along the way,” a PWD official said.

According to estimates by PWD, the city’s old drainage system can cater to a maximum of 50mm rainfall in a day. Anything more than that overwhelms the system, resulting in flooding of arterial roads and massive traffic jams.

On days of heavy rainfall over 50mm within a brief period, gaps in the water drainage capacity get exposed. Several such heavy rainfall days have been observed in the last two years when the rainfall was more than what Delhi’s existing drainage network is designed to handle. Last year, the monsoon in Delhi was about 61% in excess, with actual rainfall of 1,029.9mm against its normal value of 640.4mm. Last year Delhi received 7th highest seasonal rainfall in the monsoon season since 1901. The city recorded one “extremely heavy” (>204.4mm), six “heavy” (64.5 to 115.5mm) and 28 “moderate” (15.6 to 64.4mm) rainfall days over Delhi.

Officials explained that when the master plan was last prepared in 1976, Delhi’s population was around six million. However, as per the draft of the Master Plan Delhi 2021, Delhi’s estimated population was around 25 million in 2021 and the total urbanised area is likely to be around 920 square kilometres.

“With changing geographical and demographic conditions over the years, it is important to upgrade and modify the drainage network accordingly so that it can handle the discharge in the current situation. Over the years, there have also been changes to the system, local interventions for solutions at some places, blockage and encroachment at other places. All these need to be looked at and solutions have to be implemented,” said another PWD official.

Officials added that the irrigation and flood control department has already conducted the initial topographical surveys and other studies. The consultants have used those to come up with implementable action points.