Bangladesh is a signatory to the United Nations Convention to Combat Desertification (UNCCD). It was signed in January 1996 and after ratifying the convention the country became a party to it. The Convention came into force in 1997. Among many environmental issues facing Bangladesh, land degradation due to aridity and loss of crops due to droughts have caused considerable economic losses and human suffering than any other problem in Bangladesh. It is feared that desertification process may have started in some vulnerable areas. Therefore, participation of Bangladesh in this convention will benefit the country in resolving many problems related to it.

Bangladesh comprises of the floodplains of the Jamuna, the Padma, the Meghna and some of the smaller rivers. The Madhupur Tract, the Barind Tract, and the Akhaura Terrace stand slightly above floodplain level and the Hills lie to the East and the North. The western-northwestern part of the country is generally considered as the drier region. The total precipitation in the dry regions is low but the rainfall often occurs in sudden heavy storms, which sometimes lead to flooding and soil erosion. During the 7-month dry season in some regions, the evapotranspiration exceeds the amount of rainfall by a factor of 2.0.

Though Bangladesh is predominantly a riverine country, northwestern region is threatened by desertification. The ratio of cultivable land to rural population (acre/ person) has decreased in the northwestern region (Rajshahi Division) by 23.2% as compared to a decreased ratio of 17.2% in the whole of the country. Some geographers and ecologists claims that there is evidence of desertification from the very dry soil conditions in the Barind Tract region and the white reflectance of the soil surface on air photos and satellite imageries. Landsat imageries of the Barind Tract have been interpreted as a pronounced change in vegetation cover and soil moisture. This change has been attributed to a desert-like condition prevailing during the dry season.

The FAO experts had somewhat different view. According to them the characteristic Grey Terrace Soils of the Barind Tract were soils, which developed in response to a hydromorphic weathering process (ferrolysis).

The soils presumably always were dry in the dry season because of the very low moisture holding capacity of their silty upper layers and the heavy clay substratum (FAO-UNDP Report, 1988). Disaster Management Bureau (DMB) of the Government of Bangladesh is monitoring drought and other hazardous events. Bangladesh Meteorological Department (BMD), SPARRSO, BWDB, BARC also collaborate with BMD by providing necessary information on weather, water and soil condition and suggesting appropriate action for mitigating the effects of drought and desertification.

Attempts were made to study the seasonal aridity using meteorological data. It was observed that Bangladesh does not fall within the annual aridity limit of 20 according to Martonne Indices. However, if the monthly data were used seasonal aridity could be observed.

The seasonal aridity increases from 4 months (November- February) in the northeast/ southeast regions to 6 months (November-April) in the northwest region. WARPO advocates dry month periods of 7 months duration (November-May).

From examination of the classification of the soils of the South Asian region made on the basis of US Soil Taxonomy the soils of Bangladesh have not yet been affected in any significant way by desertification process. In Bangladesh, the process is probably at the very incipient stage.

According to the criteria set by the Convention to Combat Desertification (CCD) for defining a dry region (the ratio of annual rainfall to potential evapotranspiration (ETo) may be a maximum of 0.65), no region within Bangladesh can be termed as dry region.

However, Bangladesh does experience long spells of dry weather and moderate to severe droughts are spread over a region of 5.46 million ha. Based on annual rainfall, dry season net evapotranspiration and excess evapotranspiration (ETo-R), and dry season R/ ETo ratio value, a dry region is delineated.

Source: BARC, 1999; SOE, 2001; Chowdhury, 1995; Karim and Iqbal, 2001

Between 1960 and 1991, droughts occurred in Bangladesh 19 times. Very severe droughts hit the country in 1951, 1961, 1975, 1979, 1981, 1982, 1984, and 1989. Past droughts have typically affected about 47 percent area of the country and 53 percent of the population. An analysis of the relative effects of flood and drought on rice production between 1969-70 and 1983-84 shows that drought is more devastating than floods to aggregate production.

The Farakka Barrage has restricted fresh water flows during the dry season and caused serious problems in southwest of Bangladesh. The diversion of Ganges water by the Farakka barrage in India has contributed to the reduction of surface water availability and aggravated the desertification process in the western part of the country. The decreased stream flow also affects river morphology, salinity, ecosystem, etc., in addition to causing large-scale expansion in groundwater irrigation in the affected areas

Source: National Report On Implementation Of United Nations Convention to Combat Desertification, Bangladesh (Final Draft)