Prescription for a cleaner Dhaka

  • 16/08/2008

  • Daily Star (Bangladesh)

The time is appropriate for the government NGOs, and local communities and non-profit to collaborate more effectively and start working together towards a cleaner Dhaka, and to protect wetlands in and around Dhaka from the pressure of development to ensure biodiversity. This writer was quite alarmed during a recent phone conversation with a relative, who was visiting Boston. It was alarming because my relative told me that there were hardly any wetlands in Bangladesh that may be considered active. Until recently, there was no Wetland Protection Act in Bangladesh. As a group, wetlands, bogs, vernal pools and salt marshes are all considered wastelands. Wetlands form a critical part of our ecosystem because of their diverse animal and plant life. Unfortunately, because of lack of environmental consciousness and public education or awareness, wetlands such as, haors, lakes, beels, marshes etc. are systematically being degraded/eliminated through residential/commercial real-estate development projects. Wetlands carry out rather important functions, including flood protection. Their spongy soil composition allows quick absorption of rainwater and can naturally prevent water- logging, which is a man-made problem bigger than flooding nowadays in Dhaka, Chittagong and other major cities. Wasa Managing Director Raihanul Abedin said that water logging problem in Jhigatola area would be solved before the next monsoon as a new plan for the improvement of the sewerage system was being prepared. Don't forget, infilling of wetlands to build or expand malls, shops/residential buildings in any city could be costly and severely detrimental to the long term environmental goals of the country. Local conservation commissions should be established in every township to enforce the recently (2002) promulgated Wetland Protection Act of the Dept. of Environment. Wetlands ensure biodiversity and provide natural defence against flooding. Wetlands also naturally filter nutrients and toxicants in the polluted runoff from streets, parking lots, paved areas, building roofs and gutters or barnyards and farmland (in less urbanised districts) after rain passes through their special type of soil. Overabundance of nutrients -- for example, nitrogen and phosphorus -- from human sources such as untreated sewage, commercial fertiliser, dairy or confined animal feeding operations etc., can choke local rivers and ponds with nuisance and unchecked algae growth. Some algae certainly constitute an important part of the food chain in lakes, rivers or ponds. But algae proliferation can impose a demand for oxygen during nighttime respiration and lead to death of fish in warmer weather. Wetland attenuation of excess nutrients is a low-cost, natural way of keeping local water bodies suitable for swimming, fishing, and boating. It is of utmost importance for the economy and environment to save the wetlands, marshes, and bogs in inland or coastal areas. Without growing public consciousness and compliance/enforcement of environmental regulations, Bangladesh could lose most of its critical wetland systems to unplanned urban development projects. Of particular concern are the Ashulia and Kaliakoir areas. There will be dire environmental consequences if important wetland areas such as the above are turned into commercial areas like Tejgaon. The concept of Low Impact Development (LID) entails preserving natural landscape, minimum land disturbance to control erosion as well as soil amendment by adding compost to improve its hydrologic function. An assessment of Model Development Principle application in Virginia (USA) by Centre for Watershed Protection (2001) noted that in comparison to conventional development, use of LID could save up to 49 percent in total infrastructure cost (incl. road, gutters, sidewalks, landscaping and storm water based management practices). Studies by the American Forest Association indicated up to 40 percent savings in energy bills for homes and businesses that retained trees. Urbanization and impervious cover (IC) land induced changes in the natural water balance of streams have physical impacts that ultimately affect water quality and biological diversity. The trend of deviation from high water quality is almost inevitable at watersheds with IC level higher than 25 percent. There is ample scientific data on the indirect impact of urbanization on downstream receiving waters, exhibiting signs of degradation and presence of pollution-tolerant species in suburban watersheds (15-35% IC). However, the degradation of water quality and biodiversity is not to the extent of urban watersheds (50% IC). One retrofit LID for renovation projects is disconnection of impervious areas such as, by use of porous pavements, removing curbs or plantings in traffic islands etc. Adopting a regional approach to LID or smart growth would be very beneficial. This may involve initiatives by the law and policy makers in Bangladesh to evenly distribute economic development rather than intensifying density in Dhaka city alone. Otherwise, it will be almost impossible to clean up the Buriganga River---one of the most polluted in the country. According to Robert Zimmerman of Charles River Watershed Association "Nature was heeded when 9500 acres of wetlands were protected in the Charles River Reservation Area'. Because of this wetland conservation land area in the Charles River watershed, even when it rains frequently in the Boston area there is no flooding in the watershed. Thus daily activities do not suffer like it happens in the Peabody area of Massachusetts; businesses are not closed like in Jigatola, Dhaka. Therefore, adverse economic impact can be reversed by protection of remaining wetlands in Dhaka city. Albelee Haque is an environmental scientist in the department of environment at Boston, Massachusetts.