Wetlands of Bangladesh

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  • Topic: Bangladesh, Wetland, Mangrove
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  • Published : January 5, 2013
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BANGLADESH INTRODUCTION
by Abdul Wahab Akonda Area: 144,054 sq.km. Population: 104,000,000 (1987). Bangladesh lies between latitudes 20°34'N and 26°38'N and longitudes 88°0l'E and 92°41'E. It is bounded by India in the west and north, by India and Burma in the east, and by the Bay of Bengal in the south. Zoogeographically, Bangladesh is an interesting country lying at the junction of the Indian and Malayan sub-regions of the Indomalayan Realm. The country has a very long history of human settlement and agriculture. It is one of the most densely populated countries in the world, and the population continues to increase at about 2.6-2.9% per year. Bangladesh may be divided into four physical regions: the Ganges- Brahmaputra Delta, the Barind Tract, the Central Region and the Chittagong Region. The Ganges, Brahmaputra, Meghna and several smaller rivers unite in Bangladesh to form the largest deltaic system in the world. The flood plains and coastal mangrove swamps of this delta cover almost one-third of the country. The older parts of the delta, in the north, are comparatively high with sandy soils; the lower central parts are subject to extensive flooding every rainy season, and the accreting coastal zone (Sundarbans) is subject to regular tidal inundation. The Barind Tract consists of a group of high clay terraces of Pleistocene age in the northwestern part of the delta, except in Pabna and Bogra Districts. The soils are yellow or reddish in colour, in contrast to the grey or brown alluvial deposits of the plains. The land is undulating, and in the north, slopes rapidly up to the Himalayan foothills. The Central Region includes the Madhupur Tract, the Haor Basin of Mymensingh arid Sylhet Districts, and the Tippera Surface. The Madhupur Tract is a region of raised undulating land with reddish soils, in Jamalpur, Tangail, parts of Mymensingh and parts of Dhaka. In the north, the land slopes gently up to the foot of the Garo Hills, the southernmost of which lie within Bangladesh. The Haor Basin is a region of low-lying plains in eastern Mymensingh and western Sylhet. The basin extends north to the foot of the Garo and Khasia Hills, and east along the upper Surma Valley to the Indian border. The Tippera Surface lies directly to the south of the Haor Basin, and is partly low and deltaic and partly higher ground with a piedmont fringe to the east. The Chittagong Region, in southeastern Bangladesh, is comprised of a series of forested hill ranges and valleys running north to south parallel to the coast. There are four main hill ranges, the highest peaks exceeding 1,000m in the extreme mid-east and southeast. The coastal zone includes several large islands and estuarine systems with mangrove swamps. In

the extreme southeast of the region, there is a small coral island, St. Martin's Island, some ten km offshore. A subtropical monsoonal climate prevails throughout Bangladesh. During winter, the climate is mild and dry, with minimum temperatures varying from about 7.2°C to 12.8°C and maximum temperatures from 23.9°C to 31.1°C. The monsoon season is preceded by a period of thunderstorms from March to May. Heavy monsoon rains begin in early June and continue to mid October; they account for about 80% of the total annual rainfall. The highest rainfall occurs in northern Sylhet and in the Chittagong area, the lowest in the north and west of the country. During the period 1976-1985, the annual rainfall varied from a minimum of 1,180 mm at Jessore in 1976 to a maximum 4,785 mm at Sylhet in 1983. Temperatures during the monsoon season usually reach a maximum of about 37°C, but temperatures in excess of 40.5°C have been recorded. The relative humidity ranges from about 75% in February and March to 85-90% from June to September. There are three main types of forest in Bangladesh: wet evergreen and mixed evergreen forest in Chittagong and Sylhet, sal forest in the Madhupur Tract, and mangrove forest in the coastal zone. The wet evergreen...
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