Bay of Bengal

THE BAY OF BENGAL is a triangle-shaped water body, which is an extension of the INDIAN OCEAN to the north. It is stretched over an area of 5.7 million square mi (14.7 million square km) with an average depth of approximately 8,530 ft (2,600 m). Countries that surround the bay are SRI LANKA, INDIA, BANGLADESH, MYANMAR (Burma), THAILAND, and MALAYSIA. West Bengal and Bangladesh are located at the extreme northern end of the Bay of Bengal, and gave the bay its name. The cyclones (hurricanes) originating in the Bay of Bengal, usually before or after the rainy season, devastate the southern part of Bangladesh regularly, and occasionally they affect the West Bengal state of India and Myanmar. The bay has a significant importance in the daily life of the coastal people because it is a great source of fishing: Both sail boats and trawlers operate in the bay.

The Bay of Bengal is an extensive and wide Ushaped basin that opens to the Indian Ocean. The base of the basin is a gently sloping southward plain dissected by sub-aqua valleys, trenches, and ridges. The bottom topography is prominently marked by the Java trench, Ganga trough, Ninety East Ridge, Eighty Five Ridge and Bengal Deep Sea Fan. The Bay of Bengal is dotted with numerous islands, including Andaman and Nicobar, Union Territory of India.

The annual average temperature of the surface water is approximately 88 degrees F (28 degrees C). The water temperature varies between 82 and 102 degrees F (25 and 35 degrees C) throughout the year. Several important and large rivers of India, Bangladesh, and Myanmar flow into the bay. The GANGES, Brahmaputra, and Meghna drain into the bay from the north. Mahanadi, Godavari, Krishna, and Cauvery, the Indian rivers, feed it from the west. The IRRAWADDY RIVER of Myanmar flows into it from the east. “The rivers of Bangladesh [mainly the Ganges, Brahmaputra, and Meghna system] discharge the vast amount 1,222 million cubic meters of fresh water (excluding evaporation, deep percolation losses and evapotranspiration) into the bay” explains a Bangladeshi reference. 

A constant addition of fresh water from the surrounding rivers essentially affects chemical and physical properties of the water of the Bay of Bengal. Owing to the dilution, river mouths have a very low salinity (1 to 5 percent) as compared to open water (32 to 34.5 percent). Salinity decreases away from the coast to the open water. It also varies with the season. Discharge of fresh water from the rivers adds nutrients to the bay, predominantly along the coastal belt, thus turning it into an important fishing ground. Important species are varieties of shrimp, flounder, and snapper. Overfishing is leading to depletion of the resource. The coastal reaches of the Bay of Bengal are being polluted continuously by oil traffic, effluent discharge, and chemicals used in agriculture. International cooperation is necessary to prevent such pollution.

Before the advent of steamships, the bay was used by fishermen, traders, and occasional conquerors using sail boats and monsoon winds that reversed directions during the summer and winter seasons. During the 16th and 17th centuries, Portuguese pirates operated in the bay, but later it was widely used by British and French colonizers. Using the bay, the British colonized all the countries adjacent to it except Thailand, thus turning it into a British lake. Three major ports used by the British were Calcutta, Madras, and Rangoon.