1.1 General

Human induced land cover change has become truly global in scale and is now occurring at an unprecended scale (Turner et al. 1990), both in their rate and their geographical extent. Better understanding of the function and mechanism of such changes are essential as it has important impacts on climate, biogeochemistry and ecological complexity. Timely and up-to-date information regarding factors responsible for land cover changes and its interacting phenomenon to the surroundings contributes towards the sustainable management of natural resources for the benefit of the humankind and also for projecting future land cover trajectories.

The present study focusses on land cover assessment and monitoring of selected countries in South and South-East Asia including Nepal, Bangladesh, Burma, Laos, Combodia and Vietnam using NOAA AVHRR 1 km resolution satellite data. The broad goal of the project is to assess the major land cover types and its dynamics through time series analysis at a regional scale. It also identifies the areas undergoing major land cover transformations (i.e. "hot spot areas").

This volume is a part of a series of publications under the project and covers the case of Bangladesh. A comprehensive description about the concept, rationale and methodology of the project has been presented in Volume I-A.

1.2 Bangladesh: Study Area

1.2.1 Location and Physical Characteristics

Bangladesh, a sub-tropical monsoonal country, lies in the Indo-Gangetic plain of South Asia. It is bordered by India on the west, the north and the north east by China, Bay of Bengal on the south and Burma on the south east. It is bounded between 20034" and 26038" north latitude and 88001" and 92041" east longitude.

Consisting mainly of deltaic region with flat topography except a range of hills in the south-east, the Bengal plain is considered as the largest delta in the world. The country is criss-crossed by innumerable tributaries of three major rivers namely the Ganges, the Brahmaputra and the Meghna. The country experiences natural disasters such as excessive rainfall (causing floods), draughts and typhoons.

Typically, there are three seasons; hot or summer season (March to June), warm and humid monsoon season ( June to September) and a cold dry season (October to February). The annual average rainfall varies from 1500 mm to 5,000 mm. With 110 million people (in 1993), Bangladesh is the most densely populated country in the world (i.e. 755 persons/sqkm) except city states (Bangladesh Bureau of Statistics, 1993). [Top]

1.2.2 Present Land Cover

Once encapsuled with dense forests, Bangladesh now, is almost void of forest vegetation. The remaining forests are situated mostly in the far flung areas in the east, southeast and southwest border. A small tract of evergreen and semi-evergreen forest in the Chittagong area, deciduous forest ("sal forest") in the central part of the country and the mangrove forest in the Sundarban are the major forest types. The mangrove forest in Sundarban is the largest tract of mangrove forest in the world.

A number of estimates often conflicting are available for the total acreage of forest cover in Bangladesh. Official forest figure for Bangladesh is about 20,159.86 sq.km. (14%) in 1989 (Statistical Year Book of Bangladesh, 1989). One conservative estimate of Collins et al. (Collins et al., 1991) indicates the country has about 6% of the original forest cover.

The principal cause of deforestation is expansion of agricultural land after clear-cutting the forest areas attributed by the highest population density. However, shifting cultivation is the main reason for the deforestation in the hilly region (BARC, 1987). Population and economic pressures are two prominent factors leading to large scale clearing of forests.

Figure 1. Regional coverage of NOAA AVHRR satellite data showing Bangladesh and its surrounding countries such as India, Myanmar and China

Agriculture, being the main economic mainstay of the country, covers almost all cultivable land of the country. Multiple cropping is being practiced with rice and jute as two principal crops. Aus (deep water rice) and aman (broadcast and transplanted) are two major rice varieties.