Sustainable uses of waste ground
Restoring inflicted urban biodiversity
WASTE disposal methods have rapidly been changed since last decade in many developing countries, and our country is also following the same way of controlled disposal of waste. Increasing amount of different forms of waste is coming out from different urban areas of Bangladesh; especially solid waste generation is mounting proportionately with the growth of urban population. Most of the wastes go to the specific places called Dumping Ground or Waste Ground, which are also scientifically known as Landfill Sites.
According to a JICA study in 2004, around 3,200 tonnes of solid waste is generated every day in Dhaka city and only 44 per cent of that was possible to be collected and dumped in landfill sites. Waste landfill sites might anyway cause manifold environmental problems if not restored through proper planning and management, and could create noxious landscapes vulnerable to environment in the urban neighbourhood. After dumping wastes on the ground, the area ought to be covered with a thick layer of ordinary soil to protect environment from pollution, and thus it could increase public acceptability within the city area. Most of the landfill sites in the western countries are capped with clay soil to stop infiltration of water, and also have been installed with proper drainage for biogas and leachate collection.
Urban areas of Bangladesh entangle sizeable pockets of waste grounds that are normally unsuitable for other purposes and could be reclaimed as green spaces with different types of grasses and shrub species. These could act as wildlife habitat and enhance remnant semi-natural urban areas, which might very well edify the beauty of urban landscapes. High-quality green space enhances the standard of urban living and contributes to improve urban serenity for better health. The expansion of urban development, folded with high rate of population growth leads to unscrupulous exploitation of nature, resulting in an endangered ecology, which is alarming to the urban habitats.
Urban green spaces have ameliorative influences over ecological environment of the city as well as psychological contentment of the urban population. Thus urban greenspace can provide the minimum requirements of natural setting to prevent mental alienation of people from nature. Creating greenspace by restoring landfill sites can improve the optimal carrying capacity of the existing urban recreational area. In many developed countries, landfill sites are usually restored with grassland or woodland for public amenity space. The prospects of using restored landfill sites to ameliorate biodiversity are strong enough to deserve attention.
Bangladesh has merely 8-10 per cent of the land area that is under good canopy cover which supports approximately 5700 species of angiosperms. The IUCN Bangladesh Red Data Book (2000) has 22 amphibians, 109 inland reptiles, 388 resident birds, 240 migratory birds, 110 inland mammals in Bangladesh. This alarming rate of depletion of biodiversity is the consequence of malpractices of various kinds of human development interventions and activities. The unplanned rapid urbanization and industrialization are leading to problems that relentlessly affect natural ecosystems. As a result, the flora and fauna populations are being seriously threatened.
Restoring these landfill sites could be way of recovering or sustaining some threatened wildlife species in urban habitats. It would certainly be wise to select native species for revegetation of these lands that could attract local wildlife. Most of the plantations in our country are done with foreign fast growing species which is thought to be one of the reasons for our wildlife depletion. Native wildlife lost their habitat by this way and find no way to adopt their suitable habitat in exotic plantations. Restoring waste ground to either grassland for public open space or short rotation local species plantation can enhance total landscape quality.
Due to scarcity of fallow land or open space in major urban areas of Bangladesh, government departments and local authorities can attempt to restore these dumping grounds at certain selected locations. Closed or abandoned landfills or garbage disposal grounds represent significant land areas in urban territory, which are potential sites for ecological restoration. But there are no current guidelines which could allow for the restoration of these areas though these have many advantages in environmental, functional and aesthetic aspects for local neighbouring residents.
Land rehabilitation of these habitats include establishing diverse plant communities on these lands though determining a suitable revegetation strategy for restoring waste landfills is a very complex problem. Protocols to accomplish restoration goals must be developed, including procedural formalities that acknowledge many environmental concerns and it should be addressed by City Corporation or concerned local bodies.
Ecological constraints of these waste ground will determine the viability and financial constraints as well as the expediency while social constraints will determine the acceptability of restoration type. The importance of public acceptance of restoration increases with the intensity of human settlement in the surrounding landscape. In landscape dominated by human activity, local support for restoration projects can translate into social buffers that can greatly enhance habitat quality and increase effective habitat area.
The need for effective habitat restoration is optimistically growing, but we must move beyond simply drawing line on maps. There are still numerous major challenges to those engaged in restoration of such degraded land. These habitats are chronically hostile to plant survival and growth, and require revegetation and sufficient care and after-care to ensure that their floristic and faunal interest is retained and subsequently attractive species are maintained for amenity purposes. We need to render much greater efforts to develop methods for disposal and subsequent restoration.
Md. Lutfor Rahman is a researcher, Landscape and Biodiversity Research Group, University of Northampton, UK.
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