Wetlands play a crucial role in maintaining the ecological balance of ecosystems. Wetlands of Bangladesh have the characteristic of being sensitively in?uenced by water; supports agriculture, ?sheries and natural vegetation and maintain soil structure that is distinctive from that of surrounding uplands. But wetlands habitat of Bangladesh is under constant threat due to increase of population, commercialization of agriculture, over-?shing, siltation, pollution, ill-planned infrastructures, lack of institutional coordination and lack of awareness.
The total area of wetlands in Bangladesh is estimated to be 7-8 million hectares, or about 50% of its total land surface (Khan 1993). This includes 5.4 million hectares of open and closed lakes on ?oodplains that are inundated every year (Ali 1990). 90% of wetlands of Bangladesh are dependent on ?ow from three major rivers, but are now threatened by diversion of water in India from the Ganga-Padma River (Gopal 1995). Wetlands in Bangladesh encompass a wide variety of dynamic ecosystems, including rivers (7,497 km2), estuaries and mangrove swamps (6,102 km2), beels and haors (1,142 km2), inundable ?oodplains (45,866 km2), Kaptai Lake (manmade reservoir, 688 km2), ponds (1,469 km2), baors (oxbow lakes, 55 km2), and brackish-water farms (72,899 km2).
The country’s wide range of wetlands includes more than 700 rivers and streams, thousands of shallow freshwater lakes and marshes, ?oodplains, inshore coastal areas, and extensive estuarine systems as haors, baors, and beels, water storage reservoirs, ?shing ponds, and ?ooded cultivated ?elds. The haors, baors, and beels are of ?uvial origin and are commonly identi?ed as freshwater wetlands. Manmade wetlands include lakes, dighis and ponds.
There are lot benefits of wetland which are environment, economic and social. The environmental benefits are storage and recycling of nutrients and organic waste, storage and discharge of surface water, recharge and discharge of groundwater, natural drainage, control of ?ooding and regulation of water ?ow and water regimes, reduction of water logging and storage of ?ood water, transport of sediments and sediment/toxicant retention, storage and recycling of human waste, control of erosion and salinity, puri?cation of water and maintaining the water table high and relatively stable, relief of drought and stabilization of climate and control of microclimate, stabilization of shoreline and reduction of erosion, reduction of sediment and pollutant load, maintenance of soil structure and helping soil formation, protection against river bank erosion, helping nutrient retention/removal, protection against storm surges, helping carbon sequestration, maintaining ecosystem stability and the integrity of other ecosystems, ?sh breeding grounds, maintaining biological and genetic diversity, supporting food chains and habitat for wildlife and protecting wildlife, helping pollination, work as ecotones (vital links between land and water), habitats for a variety of resident waterfowl and a signi?cant number of endangered species of international interest and as internationally important wintering areas for migratory waterfowl, principally ducks and shorebirds.
The economic benefits are agricultural activities, crop production, freshwater ?sh production, provision of forage resources, production of wild food, production of vegetables, as agricultural land, providing forest resources, supply of irrigation water, helping stock farming, grazing places for domestic livestock, helping water duckery, supply of wildlife, supply of fuel wood, as a place of primary activities, provision of medicinal plants and genetic resources, provision of subsistence-oriented economy and livelihoods, supply of raw materials for building, construction, and industrial use, provision of places for industrial and pharmaceuticals plants, as places of primary economic activities, as pasture, and as storehouses of plant genetic material.
The social advantages are transportation, tourism and recreation, provision of settlement places, help in research and education, uniqueness, cultural heritage, cultural value, aesthetic value, heritage value, spiritual and inspirational values, bequest value, ecotourism, as leisure or recreational place, place of education and amusement, fostering of bene?cial rural-urban links, and transformation and empowerment of poor user groups as resource managers.
Wetlands perform two important functions in relation to climate hazards. It has mitigation effects through their ability to sink carbon, converting a greenhouse gas (carbon dioxide) to solid plant material through the process of photosynthesis, and also through their ability to store and regulate water. Wetlands store approximately 44.6 million tons of carbon per year globally. In salt marshes and mangrove swamps in particular, the average carbon sequestration rate is 210 g CO2 m-2 y-1 while peat lands sequester approximately 20-30 g CO2 m-2 y-1. Coastal wetlands, such as tropical mangroves and some temperate salt marshes, are known to be sinks for carbon that otherwise contributes to climate change in its gaseous forms (carbon dioxide and methane). The ability of many tidal wetlands to store carbon and minimize methane flux from tidal sediments has led to sponsorship of blue carbon initiatives that are intended to enhance those processes.
Wetlands managements need to be incorporated into a system of integrated land and water use and, indeed, into the socioeconomic system of Bangladesh. Appropriate land and water use policies/strategies related to wetlands need to be implemented. Land and water managers must pay attention to issues related to wetlands ecosystems. The National Water Policy (1999) is the main base for water management activities in Bangladesh. In this policy the main goal is stated as follows: to ensure progress towards ful?lling national goals of economic development, poverty alleviation, food security, public health and safety, a decent standard of living for the people and protection of the natural environment.
Mechanism for resolving con?icts among infrastructure, agriculture, ?shing, and land and water management approaches needs to be evolved in Bangladesh. Awareness of the importance of wetlands at all levels from policy level to project level needs to be created. Since Bangladesh is a small part of a larger hydrodynamic system that comprises several countries in the region, mutual understanding and cooperation among the co-riparian countries will be necessary to formulate any long-term and permanent solutions of wetlands security.
(Shishir Reza is an Environmental Analyst & Associate Member, Bangladesh Economic Association).
