Built on top of a former reservoir in the modern heart of Chennai, Mambalam is an important neighbourhood of Chennai facing severe water problems. The entire Mambalam basin has a residential population of around 380,000, which increases significantly with commercial activity. Theagaraya Nagar, or T Nagar, a planned neighbourhood built on the former Long Tank, is today the commercial heart of the city. By revenue, it is the largest shopping district in India, generating 20,000 crores—$2.7 billion USD—per year. The area is a relatively affluent part of Chennai, but properties directly along the canal are designated for EWS (Economically-Weaker Section) housing, and includes both informal slums and state housing boards.
The location of the Chennai Smart City initiative, Mambalam’s high visibility as a commercial centre makes it an ideal site to demonstrate the effectiveness of NBS tools to collect, clean, store and recharge stormwater in a variety of public and private spaces. Additionally, greywater from private properties will be treated and used to recharge the aquifer. “Mambalam Arms” connects different socioeconomic groups with a common infrastructure to create resilience against floods and droughts. The canal, currently a neglected backside, can be improved through increased visibility as a public space and through constructed wetlands that naturally clean the water. A waste sorting centre turns the tons of garbage currently along the canal into a local business.