| Adyar (அடையாறு / Adayaru) | |
| River | |
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Adyar in Chennai.
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| Country | India |
|---|---|
| State | Tamil Nadu |
| City | Chennai (Madras) |
| Source | Adanur Tank |
| - location | Manimangalam village, Kancheepuram, Tamil Nadu, India |
| Mouth | Adyar estuary |
| Length | 26 mi (42 km) |
| Basin | 204 sq mi (528 km2) |
Adyar (Tamil: அடையார்) or Adayar, originating near the Chembarambakkam Lake in Chengalpattu district, is one of the two rivers which winds through Chennai (Madras), South India, and joins the Bay of Bengal at the Adyar Estuary. The 42.5 km-long river contributes to the estuarine ecosystem of Chennai. Despite the high pollution levels, boating and fishing take place in this river. The river takes in surplus water from about 50 tanks and lakes, small streams and the rainwater drains in the city. Most of the waste from the city is drained into this river and the Cooum.
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Adyar river starts from Malaipattu tank (80.00° latitude and 12.93° longitude) near Manimangalam village in Sriperumbudur Taluk at about 15 km west of Tambaram near Chennai. It starts to appear as a stream only from the point where water from Chembarambakkam lake joins the river. It flows through Kancheepuram, Tiruvallur and Chennai district for about 42.5 km before joining the Bay of Bengal in Adyar, Chennai.[1][2] Here it forms an estuary, which extends from the Adyar Bridge to the sandbar at the edge of the sea, with some small islets in-between. The estuary covers an area of about 300 acres.
The river has varying depth with approximately 0.75 m in its upper reaches and 0.5 m in its lower reaches. The catchment area of the river is 530 km2. Bed width ranges from 10.5 to 200 m. If flows to a length of 24 km in the Chennai Metropolitan Area including about 15 km within the Chennai District before draining into the sea.[3] It discharges about 190 to 940 million m3 water annually to the Bay of Bengal. The discharge is seasonal with about 7 to 33 times more than the annual average during the North East monsoon season between September to December. The river is also supplied by surplus water from about 40 ponds.[4][5][6]
The present capacity of the river is 39,000 m3/s whereas the anticipated flood discharge capacity is about 60,000 m3/s. During the floods of 2005, the river had a discharge rate of 55,000 m3/s.[3]
Adyar Estuary and Creek and the Theososphical Society on the Estuary's southern side has been a haven for migratory and resident birds for years. The environmental conditions in the estuary with low salinity, good shelters and high plankton availability in the Adyar creek serves as a good nursery for fish. The flow of tidal water in and out of the creek allowed for easy travel of boats. It therefore encouraged fishing and there was a thriving economy of fish trade here. However, with the city's sewage and effluence from its various industries, for some time, emptying into the river, the biological activities in the region was affected. Although the number has been in decline due to pollution and anthropogenic activities, they still attract hundreds of birds. Even before few years the Theosophical Society has come out with a CD on 'Birds of Adyar', compiled by Trust for Environment Monitoring and Action Initiating. The proposed Adyar Poonga may be a first towards restoring this fragile but vibrant eco-system.
The river receives a sizeable quantity of sewage from Chennai after reaching Nandambakkam near Chennai. The river is almost stagnant except during the rain season. Rapid industrialisation and urbanisation has led to severe contamination of this river.[1] However, the river gets just 10 per cent of the untreated sewage being let into the three principle waterways of Chennai daily, with the other two, namely, the Buckingham Canal and the Cooum River, taking the major share (60 per cent and 30 per cent, respectively).[7]
The problem of sedimentation was not severe as the Adyar's width near Thiru.Vi.Ka. Bridge is nearly 480 m that enabled tidal effect into the waterway for about 4 km. However, it was essential to provide groynes to keep the river mouth open for adequate width and prevent inundation during monsoon. In 2011, the Water Resources Department (WRD) proposed to construct groynes to reduce formation of sand bars near the mouth the river.[8]
The Theosophical Society, Anna University, Madras Boat Club, Thenral[9] are prominent institutions located in the banks of Adyar. Adyar Estuary is now a protected wildlife reserve.
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