The geology of Chennai comprises of mostly clay, shale and sandstone. The city is classified into three regions based on geology, sandy areas, clayey areas and hard-rock areas. Sandy areas are found along the river banks and the coasts. Clayey regions cover most of the city. Hard rock areas are Guindy, Velachery, Adambakkam and a part of Saidapet. In sandy areas such as Tiruvanmiyur, Adyar, Santhome, George Town and the rest of coastal Chennai, rainwater run-off percolates very quickly. In clayey and hard rock areas, rainwater percolates slowly, but it is held by the soil for a longer time. The city’s clayey areas include T.Nagar, West Mambalam, Anna Nagar, Kolathur and Virugambakkam.

Climate

Chennai lies on the thermal equator, and thus sees little variation in seasonal temperature. Its proximity to the sea gives it a hot and humid climate for most of the year. The highest temperature is obtained in late May and early June usually about 38 °C (100 °F), though it usually exceeds 40 °C (104 °F) for a few days most years. Average daily temperature in Chennai during January is around 24 °C (75 °F), though the temperature rarely falls below 18 °C (64 °F). The lowest temperature recorded is 15.8 °C (60.4 °F) and highest 44.1 °C (111.4 °F).

The average annual rainfall is about 1,300 mm (47.2 inches). The city gets most of its seasonal rainfall from the north-east monsoon winds, from late September to mid November. Cyclones in the Bay of Bengal sometimes hit the city.

Layout

For administrative purposes Chennai is divided into five talukas. 1. Egmore-Nungambakam, 2. Fort Tondiarpet 3. Mambalam-Guindy 4. Mylapore-Triplicane 5. Perambur-Purasawalkkam.

The Chennai Metropolitan area consists of three districts namely Chennai city and the districts of Kanchipuram and Thiruvallur. The city area covers an area of 174 km² (67 mi²). The metropolitan area covers 1,177 km² (455 mi²). The city is divided on the basis of composition into four major parts: North, Central, South and West.

North Chennai is primarily an industrial area. Central Chennai is the commercial heart of the city and the downtown area. South Chennai and West Chennai, previously predominantly residential areas are fast turning into commercial areas, hosting a large number of IT and financial companies.

Contiguous satellite towns include Mahabalipuram to the south, Chengalpattu to the south west, Kanchipuram town, Sriperumpudur, Tiruvallur and Arakkonam to the west.

Administration

Chennai city is governed by the Corporation of Chennai, which consists of a Mayor and 155 Councillors representing the 155 Wards (all directly elected by the city residents), one of whom is elected by the other Councillors as a Deputy Mayor. The Mayor and Deputy Mayor preside over about 10 Standing Committees. The Corporation takes care of the civic functions of the metropolis.

The metropolitan region of Chennai covers many suburbs that are part of Kanchipuram and Thiruvallur districts. The larger suburbs are goverened by town municipalities while the smaller ones are governed by town councils called panchayats.

Chennai being the capital of Tamil Nadu houses the executive and legislative headquarters of the government of Tamil Nadu. They are primarily housed in the Secretariat Buildings, part of the Fort St George campus as well as many other buildings scattered around the city. The Madras High Court, whose jurisdiction extends across Tamil Nadu and Pondicherry, is the highest judicial authority in the state and is located in the city.

Chennai has three Parliamentary constituencies - Chennai North, Chennai Central and Chennai South. The current MPs are C Kuppusami, Dayanidhi Maran and T R Baalu respectively. Chennai elects 18 MLAs to the state legislature.

Greater Chennai Police department, a division of the Tamil Nadu Police is the law enforcement agency in the city. The city police force is headed by a Commissioner of Police and the administrative control vests with the Tamil Nadu Home ministry. There are thirty six sub-divisions of the Greater Chennai Police, and 121 police stations. Fifteen of these police stations are now ISO 9001:2000 certified. The city’s traffic is managed by the Chennai City Traffic Police (CCTP). Metropolitan suburbs are policed by the Kanchipuram and Thiruvallur police departments.

Economy

Chennai has a diversified economic base driven primarily by the automotive, IT hardware, software and services industries. Chennai is a major manufacturing centre in India. Other important industries include petrochemicals, textiles and apparels. The Chennai Port and Ennore Port contribute greatly to its economic importance. The city’s stock exchange is called the Madras Stock Exchange.

Since the late 1990s, software development and business process outsourcing have emerged as major areas in the city’s economy. The IT Corridor, on Old Mahabalipuram Road, and currently being turned into a six-lane expressway in the southeast of the city houses several technology parks. The largest of these is Tidel Park, built by TIDCO. The Mahindra World City, a Special Economic Zone (SEZ) with one of the world’s largest information technology parks, is currently under construction in the outskirts of Chennai. Nokia, among other multinational corporations, is setting up a Rs 675-crore facility at an SEZ in the satellite town of Sriperumbudur. The city has two main biotechnology parks, TICEL bio-tech park and Golden Jubilee bio-tech park at Siruseri that house bio technology companies and laboratories.

Chennai is the base for over forty percent of India’s automotive industry. A large number of the automotive companies in India are based in Chennai, mainly in the Ambattur-Padi industrial zone. Several global automotive companies such as Hyundai, Ford, Mitsubishi, TVS, Ashok Leyland, Caterpillar, Royal Enfield, TI Cycles, TAFE, and MRF have manufacturing plants in and around Chennai while BMW is soon to set up a plant. The city is a major centre in the auto ancillary industry.

The Heavy Vehicles Factory, Avadi produces military vehicles, including India’s main battle tank: Arjun. The Railway Coach building factory of the Indian Railways, the Integral Coach Factory[1] manufactures railway coaches and locomotives.

Chennai is an important centre for banking and finance. At present it is home to three large national level commercial banks and many state level co-operative banks. Several large financial companies and insurance companies are headquartered in Chennai. Many Indian banks, multi-national banks and the World Bank have located their back office operations in the city. The city serves as a major back up centre for operations of many banks and financial companies in India.

Other major manufacturing facilities range from small scale manufacturing to large scale heavy industrial manufacturing, pertochemicals and auto ancillary plants. Chennai is a textile industry hub with a large number of apparel industries located in the Ambattur-Padi industrial zone in the northern suburbs of the city. The city also has a large leather apparel and accessory industry. SEZ’s for apparel manufacture and footwear are under construction in the southern suburbs of the city.

The city is home to the Tamil entertainment (motion pictures, television, and recorded music) industry which is the largest of the four South Indian entertainment industries.