Chennai is on a flat coastal plain

Geography & Climate :

Chennai is on the southeast coast of India in the northeast of Tamil Nadu on a flat coastal plain known as the Eastern Coastal Plains. Its average elevation is around 6.7 metres (22 ft), and its highest point is 60 m (200 ft). The Marina Beach runs for 12 km along the shoreline of the city. Two rivers meander through Chennai, the Cooum River (or Koovam) through the centre and the Adyar River to the south. A third river, the Kortalaiyar, flows through the northern fringes of the city before draining into the sea at Ennore. Adyar and Cooum rivers are heavily polluted with effluents and waste from domestic and commercial sources. The state government periodically removes silt and pollution from the Adyar, which is much less polluted than the Cooum. A protected estuary on the Adyar forms a natural habitat for several species of birds and animals. The Buckingham Canal, 4 km (3 miles) inland, runs parallel to the coast, linking the two rivers. The Otteri Nullah, an east-west stream, runs through north Chennai and meets the Buckingham Canal at Basin Bridge. Several lakes of varying size are located on the western fringes of the city. Red Hills, Sholavaram and Chembarambakkam Lake supply Chennai with potable water. Groundwater sources are becoming brackish.

Chennai's soil is mostly clay, shale and sandstone. Sandy areas are found along the river banks and coasts, such as Tiruvanmiyur, Adyar, Kottivakkam, Santhome, George Town, Tondiarpet and the rest of coastal Chennai. Here rainwater runoff percolates quickly through the soil. Clay underlies most of the city including T. Nagar, West Mambalam, Anna Nagar, Villivakkam, Perambur and Virugambakkam. Areas of hard rock include Guindy, Perungudi,Velachery, Adambakkam and a part of Saidapet.

Marina Beach

Chennai is divided into four parts: North, Central, South and West. North Chennai is primarily an industrial area. Central Chennai is the commercial heart of the city and includes an important business district, Parry's Corner. South Chennai and West Chennai, previously mostly residential, are fast becoming commercial, home to a growing number of information technology firms, financial companies and call centres. The city is expanding quickly along the Old Mahabalipuram Road and the Grand Southern Trunk Road (GST Road) in the south and towards Ambattur, Koyambedu and Sriperumbdur in the west. Chennai is one of the few cities in the world that accommodates a national park, the Guindy National Park, within its limits.

Chennai lies on the thermal equator and is also coastal, which prevents extreme variation in seasonal temperature. For most of the year, the weather is hot and humid. The hottest part of the year is late May and early June, known locally as Agni Nakshatram ("fire star") or as Kathiri Veyyil, with maximum temperatures around 38�42 �C (100�107 �F). The coolest part of the year is January, with minimum temperatures around 18�20 �C (64�68 �F). The lowest temperature recorded is 15.8 �C (60.44 �F) and highest 45 �C (113 �F). The average annual rainfall is about 1,300 mm (51 inches). The city gets most of its seasonal rainfall from the north-east monsoon winds, from mid-September to mid-December. Cyclones in the Bay of Bengal sometimes hit the city. Highest annual rainfall recorded is 2,570 mm (101 in) in 2005. The most prevailing winds in Chennai are the South-westerly between May and September and the North-easterly during the rest of the year.