Sustainable Urban Wetland Management in Dhaka: Role, Status and Challenges Concerning Selected Urban Water Bodies

Abstract

Traditionally, urban wetlands have supported a multidimensional role in the city of Dhaka for a long time. However, due to challenges in the city, urban wetlands have become degraded and are presently unsustainable. Therefore, these urban wetlands urgently require improved management to revitalize them. The literature review of the research showed that there have been few specific studies on urban wetland management. Under these circumstances, considering all the constraints and challenges in the city, this research is an attempt to develop the ‘Sustainable Urban Wetland Management in Dhaka: Role, Status and Challenges Concerning Selected Urban Water Bodies’ which will further contribute to the development of the country. Thus, this research aims at the following objectives: (1) To explore the current scenario and existing role of urban wetlands in Dhaka, (2) To identify the challenges of urban wetland management and use in the city, (3) To assess the water quality parameter tests for identification of aquatic biodiversity and ecosystem conservation capabilities , (4) To identify the external factors and how these factors have influenced the variation of Dissolved Oxygen (DO) concentration across selected urban wetlands, (5) To make recommendations for sustainable conservation and management of the urban wetlands based on the overall observations of the study. In fulfilling the above objectives, an analytical framework has been developed as Urban Wetland Sustainability Framework (UWSF) Model - 1 according to the five attributes of sustainability that will provide the basis for investigating the current status, existing role and challenges of urban wetland on management and use according to the stakeholder’s perceptions concerning sustainability paradigm in the study areas. This research has also enabled the development of the Urban Wetland Sustainability Framework (UWSF) Model - 2 for identifying external factors and how these factors influence the variation of average Dissolved Oxygen (DO) concentration that can contribute to the sustainability of urban wetland from the perspective of water quality. In terms of methodology, this research has been conducted utilizing both primary and secondary data from different sources. Primary data has been collected through semi-structured questionnaire surveys with thirty number samples of study area stakeholders’ perceptions, semi-structured interviews with thirteen samples from different organizations and institutions for stakeholder expert’s perceptions and author perceptions by personal field observation. In this regard, a five-point Likert scale has been used to collect required information from these stakeholder’s perceptions as well. Further, primary data has been collected through the water quality assessment on ten parameters including Temperature, pH, DO, Biochemical Oxygen Demand v (BOD5), Chemical Oxygen Demand (COD), Turbidity, Nitrate-Nitrogen (NO3-N), Phosphate (PO4), Total Dissolved Solid (TDS) and Electrical Conductivity (EC) in the Department of Environment (DoE) laboratory during the months of October, November and December 2020 to investigate the quality of water and its suitability for aquatic biodiversity conservation. Present research further investigated the external factors and how these factors are influencing the variation of average DO concentration across selected urban wetlands by author personal field observation. In this connection, six external factors have been selected as water pollution from sewerage effluent, water pollution from industrial effluent, population density, presence of surrounding shaded trees and vegetations, air pollution and existing wetland management structures. In this research, a total of seven study areas have been selected within and near to the capital city of Dhaka. These are Dhanmondi Lake, Gulshan-Baridhara Lake, Hatirjheel Lake, Ramna Lake, Diabari Bottola Lake, Ashulia urban wetland and Birulia urban wetland. The results of the research objectives are (I) The current scenario and existing role of selected urban wetlands have been identified according to the UWSF Model – 1, as degradation of biodiversity status, low resilience to climatic impacts, limited provisions of livelihood, inconducive policy and low institutional embeddedness of community (II) The challenges of urban wetland management and use in the selected urban wetlands have been identified according to the UWSF Model – 1, as wetlands water quality degradation by pollution through human interventions and natural activities, unplanned urban development, severe fish mortality, over population pressure, lack of community and stakeholder involvement on conservation and management, increase of over paved concrete areas in the city that are producing heat, destruction of aquatic ecosystems by decreasing DO, bed level reduction of water bodies through accumulation of sludge, lack of proper functioning of drainage infrastructures, lack of livelihood restrictions on the urban context, lack of awareness on policies and adequacy of policy regime among stakeholders, lack of proper implementation of policies in the water sectors for sustainable management, lack of awareness on valuation of water bodies, lack of sustainable conservation, maintenance and management of urban wetlands etc. (III) From the results of water quality parameter assessment, the selected urban wetlands are highly dominated by anthropogenic and natural activities and at serious risk for poor aquatic biodiversity and ecosystem enhancement in the city (IV) According to the UWSF Model – 2, the study identified that average DO concentration has been affected mainly by existing wetland management structures, water pollution from industrial effluent, population density, water pollution from sewerage effluent, air pollution and presence of surrounding shaded trees and vegetations in that order. From the vi analysis, this research showed that, if the number of total external factors decreases then the average DO concentration across urban wetlands increases. Conversely, if the number of total external factors increases, then the average DO concentration across urban wetlands decreases. Therefore, there is a strong relationship between the selected external factors and their influence on the average DO concentration across the selected urban wetlands. Therefore, sustainable policies and management plans for all these factors must be implemented for the selected urban wetlands respectively (V) Based on the overall finding and analysis, this research has proposed recommendations for sustainable conservation and management of urban wetlands in the capital. This information will further help to implement sustainable management of specific wetland areas in the city and throughout the country as well.