Landuse human activities that are directly related to land, making use of its resources or having an impact upon it. Land cover is the physical attributes of the land, while landuse is a pattern of human activities undertaken within a socio-economic context. Natural land cover is changed by use of man in meeting cultivation, homestead or other demands.
Physiographically Bangladesh may be divided into three major units: hills of the north, northeast and southeast covering about 12 percent of the total area; Pleistocene terraces stretching over only 8 percent area and floodplains accounting for 80 percent of the total area. Of the three determinants, land levels in relation to flood depth are of major importance for landuse. Even occupation types in the rural areas are dependent on flooding characteristics - depth, duration and timing. There are regional variations in the distribution of different land types and landuse pattern.
Landuse pattern in Bangladesh is determined by physiography, climate and land levels in relation to flooding. In this context land includes all land and water within the national boundaries of the country. Water bodies within land areas are therefore considered to be a part of land. The use of land is of paramount importance in a country which is thickly populated and still very reliant on primary production.
Land and water are the two major natural resources of Bangladesh. The total area of Bangladesh is 147,570 sq km of which 9,734 sq km is under inland waterbodies (river, beels, etc), homesteads cover 11,227 sq km, urban fabric covers 950 sq km and forests 2,154 sq km. This account includes the shallow estuarine water surface between the offshore islands in the delta.
In Bangladesh almost one-third of the land (29%) is classed as Highland and therefore is above normal annual inundation. Slightly lower land, known as the Higher Medium Highland or MH-1, occupies over one-tenth (11.5%) of the land surface. These lands are inundated to a depth of 30 cm, mainly due to the paddy field bunds (ails) and therefore it is largely a human-induced inundation. The next lower level is known as Lower Medium Highland or MH-2, where normal inundation is between 30 and 90 cm and is largely due to improper drainage of local rainfall. Of the total area 23.2% is classed as MH-2. Medium Lowland forms 12% of the total area and is inundated between 90 cm and 120 cm, mainly by rivers which flow through these lowlands and normally rise above bank-level every wet season. Lands inundated between 180 cm and 300 cm is known as Lowland and such land occupies 7.6% of the total area. Even lower land with inundation depths in excess of 300 cm forms 1.4% of the total area of the country. The remaining 15.3% of the land area is either water bodies or urban and rural settlements. This area is increasing because of continuous urban growth.
Another way of looking at the national landuse is through the Land Utilisation Statistics, as collected and published by bangladesh bureau of statistics (BBS). The viewpoint is agricultural, so that details of the other landuses are masked. In this attempt landuse classification is as follows: net cropped area, current fallow, current waste, forest, and area not available for cultivation. In this landuse classification scheme, the areas not suitable for cultivation or not under forest is thrown into one category. This is obviously not very helpful in determining national landuse.
Presently the best estimate for landuse in Bangladesh for the year 2000 is given in the Table below. The basic sources for these estimates are the land area estimates of the survey of bangladesh, the record of rights with the Directorate of Land Records, the Land Resources Appraisal by FAO, the information provided by the Census of Agriculture 1996 and the Agriculture Sample Survey 1997, the estimations of the National Water Management Plan consultants based on water resources planning organisation (WARPO) and the estimates of the Directorate of Fisheries, the Directorate of Forest, the Ministry of Agriculture and the Agriculture Statistics Section of the Bangladesh Bureau of Statistics.
The single biggest landuse is agriculture but the basic physical features determining all types of landuse are the watercourses and standing water bodies. Bangladesh is one of the world's largest wetland areas, and during the rainy season about two-thirds of the country can be classified as wetlands as defined in the Ramsar Convention. Rivers cover an area of approximately 7,700 sq km in the wet season; this includes rivers of all sizes, except very small seasonal khals. One of the problems in estimating landuse in Bangladesh is that the area covered by water bodies increases greatly in the monsoon but dwindles to half as much in the dry season.
Another complicating factor is the effect of tides on very low estuarine chars. The level of the bay of bengal impinging on the mainland of Bangladesh is approximately two metres higher in the monsoon season (May-October) than in the dry season (November-April). Therefore, many chars and diaras, which are dry land, often, cultivated in the dry season, and go under water during the rainy season. In the coastal areas notable proportion of the agricultural land has come under shrimp culture.
Table Landuse 2000 (in sq km).
|No.||Classification||Dry Season (March)||Wet Season (September)|
|Rivers in Sundarbans||1660||1660|
|2.||Standing water bodies||4,245||9500|
|Ponds, tanks, ditches||3000||3500|
|Sundarbans (land area)||4110||4110|
|Hill scrub and grass||6900||6900|
|Plainland forest and scrub||1200||1200|
|5.||Brackish water aquaculture||1900||1900|
|8.||Non-cropped village land||8400||8400|
|Forest and woodland||1350||1350|
The main rivers such as the brahmaputra, jamuna, tista, ganges, padma, meghna and gorai are large enough to contain many islands formed from the sediments carried as bed-load. These islands are called chars in Bangla. Accretions along the sides of such rivers are known as diaras. These formations are mostly temporary topographic features since they are very susceptible to diluvion due to their unconsolidated soils and their location along flow paths. Nevertheless they are a constant feature of the larger rivers. In the estuary of the Lower Meghna chars and diaras are a major feature, increasing the size of existing islands or forming new islets, only to be washed away in few years. The total area of chars and diaras in the dry season has been estimated at 2,163 sq km, which is reduced to 1,463 sq km in the wet season. It is obvious that such estimates hold good for only one season and may vary by as much as twenty percent in consecutive years.
Standing water bodies are a very important feature of the Bangladesh countryside. The natural standing water bodies are known as haor, beel or baor. Haors are large shallow depressions in the northeast of the country and lie mostly within the physiographic unit known as the Haor Basin. They become large lakes in the wet season, but mostly drain out in the dry season, when only a few pockets of water remain. Baors are oxbow lakes, found mostly in the Moribund Delta. The area of these fluctuating water bodies depends on the referring time of the year. The whole of the Haor Basin has the aspect of an inland sea of 4,500 sq km extent in July and August, but is reduced to one-tenth by December. Thus any accounting of landuse in Bangladesh must emphasise the seasonal changes. In the dry season the Haor Basin is largely agricultural land but in the wet season it is largely a fishery. The same holds true for most of the beels. The total area of beels in the dry season has been estimated at 177 sq km, and this may increase to 1,500 sq km in the wet season. The area of baor, estimated at 55 to 58 sq km, does not fluctuate significantly.
Ponds for multipurpose use are a common feature of the countryside. In lowland areas they are an integral part of the settlements since they provide the earth on which the homesteads are built. They are even more common on flood-free land because they are secure from flood damage and can be used as high value fisheries. These excavated ponds (formerly termed Tanks) are a major source of the higher value fishes such as carps. The total area of ponds has been estimated to be 1,469 sq km by the Directorate of Fisheries but the 1996 Agriculture Census enumerated 3,489 sq km of ponds, tanks and ditches.
The single largest water body is the kaptai lake, which covers 742 sq km when at full level towards the end of the rainy season, but is reduced to 583 sq km at the end of the dry season. Here too the effect of the seasons is very noticeable. Over 100 sq km of hillsides and valleys are exposed during the drier part of the year and an estimated 20 sq km of the exposed level area is cultivated to rice and vegetables.
Nearly one-seventh of the country is said to be forestland but only slightly over half of this is under tree cover. The single largest forest area is the sundarbans, with a total area of 5,770 sq km, of which 1,660 sq km is water and 4,110 sq km is land. This is the world's largest mangrove forest. Mangroves have also been planted along the coastline and now form a forest of over 1,400 sq km. The hill areas in the north, northeast and southeast contain 12,900 sq km of tree cover, scrub, bamboo and shon (Imperata arundinacea). The tree cover has been greatly reduced in the chittagong hill trackts. In the Hill Tract districts the Unclassed State Forest (USF) land is largely scrub and grass, interspersed with jhum land. The plainland forest of some 1,200 sq km extent is mainly on the madhupur tract with small patches on the northern reaches of the barind tract. These are mainly Shal (Shorea robusta) but in many places are being replaced by the Forest Department with Australian species. A large part of these forests has been reduced to scrub or converted into agricultural land.
The seasonality factor has a strong impact on cultivation. In the relatively dry months (November to April) the cropping pattern is very different from that in the wet months (May to October). In the dry season the main crops are boro rice, wheat, pulses, oilseeds and vegetables. Towards the end of this period aus and jali aman (floating aman) are sown. In March the area under crops is more than at any other time of the year. At the onset of the rainy season the dry season crops are harvested, and the fields contain mainly boro and aus rice and Jute. By August these are harvested and shail aman (a variety of aman rice) is sown. In September land inundation generally reaches its peak and the area occupied by field crops is at its lowest. Whereas several dozen crops occupy the 51,000 sq km of cultivated land in early March, in September the only field crops of note are shail and jali aman, jute, sugarcane and some types of summer vegetables. The category Seasonal Fallow includes land that is inundated in the wet season and thereby forms some of the best inland fisheries. Any land that goes under water is a potential fishery and therefore large stretches of agricultural land that are inundated, such as in Brahmanbaria district, become seasonal fisheries and can produce more protein per hectare than crops.
Freshwater aquaculture is carried out in ponds in all parts of the country. Brackish water aquaculture is carried out in large areas in the southeast and southwest, where brackish tidal flow is available. The enclosed areas where such aquaculture is carried out total approximately 1,900 sq km and form the dominant feature of the landscape all along the northern bounds of the Sundarbans, and along the Cox's Bazar coast. Along the Cox's Bazar coast there are thousands of salt beds where salt is manufactured in the dry season. Some of these beds are used for aquaculture in the wet season.
The rural inhabited areas are thickly dotted with settlements. These consist of homesteads, groves of trees and bamboo, scattered trees and wasteland, public buildings and school playgrounds. Each village has its agricultural land and its settlements. The inventory of landuse divides these areas into three parts: Cultivated Land, Rural Built-up and Non-cropped Village Land. Rural Built-Up consists of the to Homesteads and the area taken up by rural institutions. The Census definition of Homestead area is that taken up by houses and other structures, courtyard and the land occupied by the access passages. Homesteads occupy 5,500 sq km and institutional structures take up 1500 sq km.
Non-cropped Village Land includes Culturable Waste (5,800 sq km), bamboo groves (1,250 sq km) and forest and woodland (1,350 sq km). Some of the Culturable Waste category of land is inundated seasonally and form a valuable part of the inland fisheries. The urban category with 7,000 sq km, includes all built-up land within areas declared as being urban, that is settlements with a population of 5,000 or more having typical urban characteristics. Nearly half the urban area is in the Dhaka Metropolitan Area, with much of the remainder in Chittagong, Khulna and Rajshahi Metropolitan Areas. Many rural towns have declared large areas to be in their municipalities. Their villages and agricultural areas have been excluded from the urban area. Rural infrastructure includes places of worship, graveyards and other communal areas. Both these categories have been expanding, particularly at the expense of cultivated land.
The extent of water surface in the Estuarine Area varies seasonally. In the dry season the level of the Bay of Bengal is lower and the seas are calmer than in the wet or monsoon season. Moreover the rivers are lower due to lesser flow. The extent of chars and diaras increase several fold. In the wet season they are submerged and therefore they have been included in the Estuarine Area. The seaward boundary of this category has been arbitrarily set at the thirty-fathom line. The 8,600 sq km of the estuarine area is a part of the estimated 31,000 sq km of territorial waters, beyond which is the 69,000 sq km of the Exclusive Economic Zone (EEZ) in the Bay of Bengal. The changes in the land cover/landuse pattern in Bangladesh suggest that the country's land resource is under considerable environmental stress due to deforestation, extension and intensification of agriculture, particularly rice monoculture and decline of natural vegetation cover. [Haroun Er Rashid and M Shamsul Alam]
Bibliography UNDP, Landuse in Bangladesh, Selected Topics: Agriculture Sector Review, UNDP, Dhaka, 1989; Haroun Er Rashid, Geography of Bangladesh, University Press Ltd, Dhaka, 1991; Government of Bangladesh, National Water Plan Report, Volume 1, Ministry of Irrigation Drainage and Flood Control, Government of Bangladesh, 1991; UNEF/FAO, GEM Report, series 23, Report of the UNEP/FAO Expert Meeting on Harmonizing Land Cover and Landuse Classifications, Geneva, 23-25 November, 1993; Bangladesh Bureau of Statistics (BBS), Statistical Year Book of Bangladesh 1996, BBS, Ministry of Planning, Government of Bangladesh, 1997; Bangladesh Bureau of Statistics (BBS), Agriculture Sample Survey 1997, BBS, Ministry of Planning, Government of Bangladesh, 1999; Bangladesh Bureau of Statistics (BBS), Census of Agriculture 1996, BBS, Ministry of Planning, Government of Bangladesh, 1999; Water Resources Planning Organisation (WARPO) Land and Water Resources, Draft Development Strategy, National Water Management Plan, Volume 4, WARPO, Ministry of Water Resources, Government of Bangladesh, 2000.