Failure to fix all missing links in storm-water drains may have aggravated flooding in Chennai

Chennai's failure to fix "missing links" in storm-water drainage, identified in a World Bank-funded project, is being blamed for the city's flooding during cyclone Michaung. Elected representatives and residents said many of the roads covered in the project were flooded. Hydrologist Sakthivel Beemaraja said engineers should check if disposal points to canals were connected and assess the impact of encroachments. Disaster expert N. Mathavan said there was a need for a complete audit of the storm-water drains. Former CMDA Chief Planner K. Kumar said the city's flat terrain and low-level of sponginess add to the calamity.

Failure in fixing all “missing links” in storm-water drainage, identified as part of a World Bank-funded project, is being cited by a section of stakeholders as one of the reasons for the aggravated flooding in several parts of the city in the wake of cyclone Michaung.

The World Bank had funded the project in the zones of Adyar, Kodambakkam, Teynampet, Anna Nagar, Thiru. Vi. Ka. Nagar, Royapuram, and Tondiarpet, along with 144 roads, covering 44 km of drains. An Environmental Impact Assessment Report on ‘Missing Links Storm Water Drainage Project for the Core City Areas’, prepared by the Greater Chennai Corporation (GCC) in January 2021, said the cumulative length of missing links in these zones was 11.949 km. Elected representatives and residents said many of the roads covered in the project had witnessed flooding and demanded corrective action.

Ezhilan Naganathan, Thousand Lights MLA, said roads such as Cathedral Road, Dr. Radhakrishnan Salai and Thirumalai Pillai Road, which were covered in the project, were among the flooded roads. Water had receded here after six hours.

A resident of Velachery, Kumara Raja, said the Velachery Main Road was heavily flooded, exposing the vulnerability of the city to flooding, and stressed the need to find the actual cause of non-functioning of drains, and validation for the non-functioning of drains where works on missing links were completed.

Hydrologist Sakthivel Beemaraja said engineers should check if disposal points to canals such as the Buckingham Canal were properly connected and assess the impact of encroachments along the 7-km stretch of the Canal. “Engineers are seeking a solution. There is enormous pressure,” he said.

So far, approximately 3,331 km of storm-water drain network have been provided for the city, including 876 km that was additionally constructed during the last two-and-a-half years.Disaster management expert N. Mathavan, who worked on vulnerability mapping for the city, said there was a need for a complete audit of the storm-water drains and improving them based on current data. “Since the occurrence of hydro meteorological-related disasters are frequent, it is pertinent to ensure a continuous assessment of the existing networks, including maintenance and monitoring throughout the year, with a separate authority on the lines of CMDA.... This will prevent multiple agencies from monitoring the city’s network,” he said.

Former CMDA Chief Planner K. Kumar said while these events were bound to occur, efforts must be made to combat the resulting disruption. “Compared to the urban floods in Dubai, New York, Hong Kong, Italy and China a month ago, the calamity that Chennai faced isn’t very significant. Roads are primarily meant to function as channels to drain water. The storm water drains have been incorporated in the road network in such a way that it does not tamper with the traffic flow,” he said.