Kosasthalaiyar River, also known as Kortalaiyar, is one of the three rivers that flows through Chennai. Not as familiar as the other two, it flows along the northern peripheries of the city, draining through the Ennore creek into the Bay of Bengal. 136-kilometres long, its joins the Nagari river at the Poondi reservoir, a major source of water for the City.

The Adyar river originating near the Manimangalam ery in Kanchipuram district, about 40 Km from Chennai’s centre is the shortest of the three rivers winding through this city. The 42.5-kilometre river acts as a carrier for surplus waters from over 200 tanks and streams upstream as well as wastes and effluents from storm water drains in the city and hosts activities like boating and fishing along brief stretches. Travelling mostly through the southern part of the city, it crosses the Kotturpuram and Adyar bridges before it joins the Bay of Bengal at the Adyar estuary.

The Manimangalam tank, an irrigation tank ("ery"), is one of 1000's of such water bodies that dot the landscape of Chennai and its hinterlands. These ery's were built and designed as water reservoirs that were used primarily to irrigate agricultural fields. A key feature of these water bodies is the cascading arrangement between them, such that most of these tanks are interconnected through channels that allow water to flow from one to another. As the city of Chennai has expanded into its hinterlands, changing land-use and landscape in these spaces have further imperiled the complex ecologies of these waterscapes.