Changing Pattern of Wetlands and its Impact on Environment of Dhaka City

Abstract

Dhaka, the capital city of Bangladesh is one of the populous Mega cities in the world. High density population as well as shortage of land causes intense densification in the existing built up. Rapid population growth creates extra pressure on the land of already overcrowded Dhaka city and the city is expanding in an unplanned and uncontrolled manner. One of the major adverse impacts of unplanned growth is destruction of environmentally sensitive areas. Dhaka city had a large number of wetlands both big and small, which includes rivers, canals, lakes, lowlands etc. But the wetlands have been shrinking with the passage of time. In recent years the speed of conversion of wetlands for housing and other infrastructures emerged as an alarming issue considering its adverse impact on environment. This study mainly focuses on three issues: i) Changes of wetlands in and around Dhaka city ii) Problems appeared in the city due to wetland change iii) Government's implications regarding wetland change. This research documented the extent of wetland change since 1960. To accomplish the work top maps of 1960 and three images of different years (Land sat TM, 1988; ALOS VNIR, 2008 and Goggle earth, 2008) were used. Findings reveal that a large portion of the wetlands has been lost and the rate of destruction of wetland is alarming. During the total study period (1960-2008), the city has lost 33% of water bodies and 52% of lowlands. During the period 1960-88 the water bodies decreased about 30 hectares per year and between 1988-2008 decreased about 6 hectares per year and lowlands decreased 29 hectares per year between 1960-1988, 315 hectares per year between 1988-2008. It is clearly observed from the analysis of change in land use dimension of selected wetlands areas that wetlands are mainly converted to built-up areas. It is also revealed from this analysis that the rate of transformation of wetland is highly related with urban settlement. This research tried to apprehend the perception of local people regarding the loss of wetlands through questionnaire survey. It is evident from the views of surveyed respondent’s mainly real estate companies and government organizations are involved in wetland loss and water logging is the main impact of wetland loss. The water logging becomes a burden for the inhabitants of Dhaka city and creating adverse social, physical, economic and environmental impacts. Interruption of daily work, children's problem going to school, disruption of electricity, risk of run of motor vehicle, damage of houses, problems in getting drinking water, sanitation problem, creating unhygienic situation and suffering from the disease are the encountered effects of water logging on city life. Respondents viewed that to overcome the water logging problem, all illegal structure from the wetlands need to remove immediately. This research carried out a thorough assessment of prevailing plans, acts, rules and regulations for wetland management. The present wetland management of the public agencies has been critically analyzed and their overlapping and conflicting areas were identified. Activities of different environmental groups were also reviewed in this study. The investigation undertaken for this study reveals that the present management practices of government organizations are very weak and not at all systematic. The existing legal tools of different agencies are not exercised properly. Overlapping of functions among the agencies creates conflicts in management. The coordination status of government organizations are poor but the PLDCs, local influential people and others, those are involved in wetland change are highly organized and well coordinated. This study delivers the essence that combined effort is necessary from the part of involved stakeholders, like local people, NGOs, local government body, central government and civic organization to implement the conservation strategies of wetlands. Political will and government commitment is also needed for this purpose. In conclusion, some recommendations are made regarding proper demarcation of wetlands, strengthening the relevant GOs, strict development regulation and proper enforcement of laws towards conservation of wetlands.