Dhaka Courier

Modeling Environmental Dynamics of Wetlands in Bangladesh

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Existing theory of disaster capitalism smashes away the natural resources around the world. Global rent-seekers are targeting how to make more profits from the water, river, swamps and marsh lands. Global temperatures are augmenting, sea-levels are uprising and oceans are warming. Apart from that, climatic and environmental hazards which are escalating continuously make mass people more concerned about the existence of life, nature and environmental health.

Setting the Scene

Whatever wetlands are very imperative natural resources which store and absorb carbon, reduce floods, relieve droughts, reduce storm surges and protect coastlines. Wetlands territories have an enormous magnitude as they are ecosystems of high biodiversity. They are also natural regulators of climate and water cycle and help control floods and droughts. It generates hydrological resources that supply water to populations in their area of influence, both for consumption and for agricultural and livestock use, and are also areas of work activity or recreation for humans such as fishing and tourism. Wetlands are restoring mangroves in West Africa and working as sequester of carbon in Nordic-Baltic region. Coastal wetlands such as salt marshes, mangroves, sea grass beds, and coral reefs act like shock absorbers. They reduce the intensity of waves, storm surges, and tsunamis, shielding the 60% of humanity who lives and works along coastlines from flooding, property damage and loss of life.

The frequency of disasters worldwide has more than doubled in just 35 years, and 90% of these disasters are water-related. Even more extreme weather is predicted going forward. Wetlands play a significant role in stabilizing Greenhouse Gas emissions and blunting the impacts of climate change. Peat lands, mangroves, and sea grass store vast amounts of carbon. Peat lands cover about 3% of our planet’s land and store approximately 30% of all land based carbon-twice the amount than all the world’s forests combined. Wetlands are the most effective carbon sinks on Earth.

Wetland as a Natural Resource

Wetlands play a crucial role in maintaining the ecological balance of ecosystems. Wetlands of Bangladesh have the characteristic of being sensitively influenced by water; supports agriculture, fisheries 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-fishing, 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 floodplains that are inundated every year (Ali 1990). 90% of wetlands of Bangladesh are dependent on flow 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 floodplains (45,866 km2), Kaptai Lake (man-made 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, floodplains, inshore coastal areas, and extensive estuarine systems as haors, baors, and beels, water storage reservoirs, fishing ponds, and flooded cultivated fields. The haors, baors, and beels are of fluvial origin and are commonly identified as freshwater wetlands. Man-made wetlands include lakes, dighis and ponds.

Environmental, Economic and Social Advantages

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 flooding and regulation of water flow and water regimes, reduction of water logging and storage of flood water, transport of sediments and sediment/toxicant retention, storage and recycling of human waste, control of erosion and salinity, purification 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, fish 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 significant 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 fish 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 beneficial rural-urban links, and transformation and empowerment of poor user groups as resource managers.

Wetland Resources and Climate Security

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.

However, depending on their characteristics, some wetlands are a significant source of methane emissions and some are also emitters of nitrous oxide which is a greenhouse gas with a global warming potential 300 times that of carbon dioxide and is the dominant ozone-depleting substance emitted in the 21st century. Excess nutrients mainly from anthropogenic sources have been shown to significantly increase the N2O fluxes from wetland soils through de-nitrification and nitrification processes.

The level of CO2 in our atmosphere has increased 40% since pre-industrial times. To limit the impacts of climate change, the global community via the Paris Agreement is seeking to stabilize and reduce Greenhouse Gas emissions, and limit the increase in global average temperature this century to below 2°C.

Management of Wetlands in Bangladesh

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 fulfilling 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 conflicts among infrastructure, agriculture, fishing, 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.

Concluding Remarks

Global research on hydrology and climate explains, Bangladesh is an innocent victim of climatic hazards and environmental degradation. Other hand, our motherland greening the economy and would be a middle income by 2021, in this context wetland resources play crucial role. As wetlands are working to sink carbon, implementing a comprehensive scientific enquiry, hydrodynamic analysis, modeling of the physical effects on wetlands and more research on wetlands of Bangladesh should be included. Hence, wetlands mapping, monitoring and protecting through geographical information system, remote sensing along with other sciences are very important.

The writer is an Environmental Analyst & associate member, Bangladesh Economic Association.

  • Modeling Environmental Dynamics of Wetlands in Bangladesh
  • Issue 31
  • Shishir Reza
  • Vol 35
  • DhakaCourier

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