Green space in Dhaka North declines 66% in 3 decades: Study
Around 47% of the 194.2 sq km area of Dhaka northern part was green in 1992, which dropped to 31% in 2002, to 18% in 2012, and declined further to 16.17% in 2022
Green areas like parks, playgrounds, and urban forests – crucial for controlling temperature in a city – have shrunk 66% in the Dhaka North City Corporation over the last three decades, according to a recent study.
In 1992, the Dhaka North region had 92.21 sq km of vegetation, which dropped by around 66% to 31.40 sq km in 2022, said the study titled "Prospects and challenges of achieving sustainable urban green spaces: A case study of urban greening in Dhaka North City Corporation (DNCC), Bangladesh", published on 9 May in US-based journal Plos Sustainability and Transformation.
Around 47% of the 194.2 sq km area of Dhaka northern part was green in 1992, which dropped to 31% in 2002, to 18% in 2012, and declined further to 16.17% in 2022.
The study also shows that the grey space – urban areas that are not green – in Dhaka North increased by almost 95% from 1992 to 2022, decreasing the areas of water bodies by 32.4% during the period.
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Barren land areas, which can be used for planting trees, in Dhaka North have dropped from around 11 sq km in 2012 to 2.2 sq km in 2022, said the study.
Professor Mashura Shammi of department of environmental sciences at Jahangirnagar University, and Associate Professor Farhadur Reza of Department of Urban and Regional Planning at the same University conducted the study. Aristol Chandra Sarker and Abid Azad Sakib were the assistant researchers.
The researchers used Landsat data – satellite imagery of Earth – from the US Geological Survey's database.
"The way Dhaka's green space is shrinking day by day, there will be no greenery in Dhaka after a while. Dhaka South has less green space than that in Dhaka North. We are conducting a study on the Dhaka South area and the data we are getting from there is more alarming," Farhadur Reza told The Business Standard.
The researcher said green areas in Dhaka are vanishing fast to accommodate an increasing number of people in it by realising various projects and constructing residences. Decentralising the development projects and government services is necessary to ease the pressure on Dhaka.
Besides, the existing green areas should be protected through government measures, he added.
The study said 44.8% of Dhaka's total area was open space in 1975, which dropped to only 24.5% in 2005. The researchers also cited a 2013 study, which said around 88% of Dhaka city's dynamic core area is built-up by replacing green zones or wetlands.
Due to insufficient vegetation area, Dhaka city's carbon sequestration – the process of capturing and storing atmospheric carbon dioxide – is unsatisfactory. The cooling and humidifying effect of medium-sized green areas was most noticeable during high-temperature days, said the study.
Furthermore, the water basins within green spaces have a significant impact on local cooling and humidity. The loss of urban green zones and wetlands can promote an urban heat island effect, a microclimatic event with significant temperature rise and amplifying heat waves.
More initiatives essential to make Dhaka greener
The study recommended the authorities to take measures for realising the Sustainable Development Goal 11 which aims to make cities inclusive, safe, resilient and sustainable.
The government has already taken initiatives to protect water bodies through policies and laws such as "The Playground, Open Spaces, Parks, and Water Bodies Conservation Act 2000" and "The Public Water Body Management Policy 2009."
Government-led wetland restoration projects, including the Hatirjheel Area Development Project, have also helped restore natural water features in Dhaka North.
Dhaka North officials have said they have an initiative to plant 2 lakh trees in their area in the next two years. They also introduced the post of a "chief heat officer" to address the heat stress caused by climate change and the urban heat island effect.
According to the United Nations Environment Programme (UNEP), an ideal city should have at least 25% green space, but Dhaka North has only 16.17%, said the study.
With a population of more than two crores, Dhaka has witnessed a rise in temperature of nearly 3 degrees Celsius in the last 20 years, according to a study titled "Surface urban heat island intensity (SUHII) in five major cities of Bangladesh: patterns, drivers, and trends."
The study said human populations play a major role in shaping cities and influencing the thermal environment of urban areas, so the increase in population both expands city size and is accountable for the rapid transformation of natural land cover to impervious surfaces.
Another study titled "Political Economy of Urban Green Spaces of Dhaka City'" released by the Urban and Regional Planning Department of Bangladesh University of Engineering and Technology (BUET) in March said only 8.5% of the land in Dhaka has tree cover.
Dhaka North City Corporation Chief Town Planner Maqsud Hashem told TBS that in 1992 there were many private farmlands in the area covered under the latest study. A huge portion of those areas have been converted into grey spaces.
"I think public green space has increased in Dhaka North in the last few years. We have saved several parks. We are also reclaiming canals and planting trees on their banks, which increases the green area," he said.
