A major cause of land degradation in Bangladesh is overexploitation of biomass -- both from the cultivated field and the wooded areas. The consequence is accelerated water and wind erosion of the topsoil. Unsustainable clear felling of trees leads to decrease in soil moisture content and potential decline in soil fertility due to nutrient losses. Uncoordinated slash and burn cultivation in the southeastern hills is another practice that causes land degradation through excessive runoff and accelerated soil erosion and mass wasting. Degradation of land in several parts of Bangladesh, especially in the northwest, is largely the result of direct human intervention.

The collective expression of numerous forms of land degradation in arid/semi-arid lands is desertification. It does not have any precise meaning, but generally connotes a land degradation process in which human actions (especially in arid, semi-arid and dry subhumid environments) weaken the resilience of the agroecological system and reduce the biological potential of that system. In reality, desertification is the cumulative consequence of climatic variability in a fragile ecosystem and human activities beyond the threshold limit. And this is largely what is happening in the northwestern Bangladesh where rainfall is both variable and much lower than the national average; and human actions are exacerbating the decline in potential productivity.

Desertificiation in the present world affects about one-sixth of the world's population. Our understanding of the dimensions of desertification have been greatly enhanced by the 1977 UN Conference on Desertification (UNCOD), which followed the Sahelian (West Africa) drought of 1968-73. The UNCOD accepted the view that desertification is the diminution of the biological potentials of land, and can ultimately lead to desert-like conditions. Interest in desertification gained further momentum during the 1992 Earth Summit at Rio with a plan to combat desertification and drought as part of Agenda 21 -- ultimately leading to the Convention to Combat Desertification. Bangladesh is a signatory to this convention.

The term 'desertification' was first used by Aubreville in 1949 who described it "as the changing of productive land into a desert-like wasteland as a result of man-induced soil erosion". Since then many researchers have interchangeably used 'land degradation' and 'desertification' as synonymous phenomena in order to indicate progressive soil erosion and loss of vegetative cover as evidence of land degradation and processes leading to desert-like conditions. It is unfortunate that desertification has been given many different definitions and connotations by researchers and public agencies which have created confusion and ambiguity in interpretation. Of the various definitions, the one adopted by the 1992 Rio summit seems more precise than others. In fact, it is a modification of the 1990 definition (of desertification) by the United Nations Environment Programme (UNEP). The Rio definition of desertification says that it is "land degradation in arid, semi-arid and dry subhumid areas resulting from various factors, including climatic variations and human activities." (Drought, on the other hand, is a climatological phenomenon, implying a less-than-normal rainfall. It need not be the cause of desertification, but it acts as a catalyst of land degradation through a combination of stresses on soil and vegetation, and of human interventions of land abuse during the spells of periodic droughts.)

Vulnerable area in Bangladesh

In-depth and detailed studies are lacking in Bangladesh which could delimit precisely the area affected by or susceptible to land degradation (desertification). Nevertheless, symptoms of such degradation which have become evident in northwestern Bangladesh in recent years is too pronounced to be ignored. For planning purposes, the zone in west-northwest Bangladesh, bounded on the east by the 1600 mm isohyet, might be identified as vulnerable to land degradation. This is a region which has (a) average annual rainfall much lower than the national average of 2300 mm, (b) highest rainfall variability in the country (17.5%), and (c) suffered frequent seasonal droughts in the pre-monsoon (March-May) season. In terms of geographical extent, this vulnerable area includes the greater districts of Rajshahi, Kushtia, northwestern Jessore, Pabna, western Bogra and southern Dinajpur. It should be noted that this area also includes the fast-shrinking (due to human intervention) Chalan Beel wetlands as well as the Barind Tract.

Landsat imagery of the 1980s indicated a definite change in vegetation cover and soil moisture in the Barind Tract, which resembled an arid zone during the months of March-April. Since the early 1990s, attempts have been made to reverse the process of land degradation/desertification in the Barind region through the efforts of the Barind Multipurpose Development Authority (BMDA). The programmes of the Authority include such measures as sustainable utilisation of groundwater through deep tube wells (DTW) [arsenic being not a problem here], water retention structures and pond re-excavation for greater surface water use, and extensive tree (fruit and timber) plantation to restore the vegetation cover. Regular monitoring of water table (fortnightly) ensures a balance between groundwater withdrawal and recharge. One of the objectives is to transform the once monocultural Barind region into a triple-cropped region. Indeed, pre-BMDA cropping intensity of 117 per cent has now increased to more than 174 per cent on account of irrigation facilities. Besides, tree plantations along the roads are nurtured through caretaking by the local people through a participatory mechanism.

Policy options and

way forward

The priorities in an action programme to combat land degradation/desertification in Bangladesh should be to (a) combat the process in already degraded areas, and (b) monitor and implement preventive measures in lands that are not yet degraded, but are vulnerable. In both efforts, a synergetic participation of local communities, NGOs, government agencies, and the private sector is essential. Initially, however, an action plan to combat degrad ation/desertification in Bangladesh would be handicapped by an inadequate database. Hence, a combat programme should begin with the strengthening of the knowledge base of the vulnerable areas. Goals toward that end should include research needs in: (a) conducting surveys of human, livestock, land, water and vegetation resources;

(b) assessing the status, cause and rates of degradation; (c) identifying the indicators of degradation; (d) developing a network of observation systems with a view to establishing environmental information system at the national level, and (e) analyzing the social and economic implications of the degradation process.

In the context of west-northwest Bangladesh, a series of priority measures for combating degradation/desertification could be suggested here: (a) Introduction of ecologically sustainable land use plan; (b) Rehabilitation of the degraded lands and sustain their productivity though soil and water conservation; (c) Protection of the existing trees and other vegetative cover; (d) Expansion of the vegetative cover through afforestation, reforestation, agroforestry and social forestry; (e) Establishing woodlots on khas lands as sources of fuel, along with the introduction of energy-saving cooking stoves; (f) Conjunctive use of surface and groundwater along the practice followed in the Barind region; (g) Evaluating and addressing the socioeconomic determinants (including impacts of urbanisation and industrial expansion) on land degradation/desertification; (h) Developing national programmes for drought preparedness, including early warning systems and drought relief measures; and (i) Creating awareness among the local population and motivating them to actively engage in combat measures -- in partnership with government and non-government agencies.

Parallel to combat measures is needed a monitoring plan for degradation/desertification in Bangladesh. This monitoring or surveillance plan should be based on the recognition of desertification indicators and the establishment of standards for comparison and evaluation. The UNEP, FAO, UNSCO and IUCN have been engaged in mapping and monitoring desertification, and Bangladesh can learn from their experiences in developing an environmental monitoring plan for the vulnerable areas of the country.

The three categories of environmental components of a monitoring plan are physical, biological and socioeconomic. Some of them are given below, from which a pragmatic selection could be made for standardisation to serve as indicators for monitoring in west-northwest Bangladesh.

(a) Physical components of monitoring:

-soil depth, fertility and organic content;

-soil erosion rate;

-amount and intensity of local rainfall;

-intensity and frequency of wind storms and norwesters;

-groundwater table and its quality;

-surface water (quality and seasonal supply);

-shrinkage up of wetlands.

(b) Biological components of monitoring:

-type, quality and distribution of biomass;

-fuel and fodder availability;

-trend in crop yield;

-livestock population, yield and composition;

-quality of the fish habitat, and fish output;

-faunal species.

(c) Socioeconomic components of monitoring:

-land and water use practices;

-settlement pattern, shrinkage, growth relocation;

-demographic structure;

-local and regional migration;

-land ownership (and landlessness);

-income and assets;

- diet, nutrition, health.

The terms 'land degradation', and 'desertification' (and sometimes 'drought') have been used so widely and in such diverse contexts that they have often created problems in interpretation among policy makers. The dynamics of land degradation/desertification are best understood within the context of the natural environment and human intervention into that environment. Land degradation/desertification is not an isolated climate induced phenomenon, rather it is an aberrant and unsustainable human response to the broad parameters of the natural environment. With a dedicated agenda, local action and appropriate technology, it is not impossible to offset the effects of land degradation, and strike an equilibrium between the seemingly incompatible process of land degradation and sustainable land management.

Dr K B Sajjadur Rasheed is Professor of Geography and Environment at the University of Dhaka.