by Syed Zainul Abedin
DHAKA, Oct. 31 (Xinhua) -- Dhaka, once a city of lush green forests and verdant grass fields, has gone through drastic environmental changes over the past four decades due to rapid urbanization and unplanned economic expansion.
The capital city of Bangladesh and now home to over 15 million people began to lose its greenery, lawns and huge swaths of open spaces in the wake of rapid and unplanned urban settlements since the country became independent in 1971.
With millions of people flocking to the one of the fastest growing megacities in the world in quest of a better life, Dhaka is now in dire state and considered as one of the least liveable cities in the world.
Hundreds of brick kilns on the fringes of the city also contributed to air pollution, killing trees and resulting in severe health hazards to people, such as asthma, pneumonia, anemia, mental imbalance and other related ailments.
Experts say urban forest plays an important role in ecology of human habitats as they filter air, water and sunlight, provide shelter to animals and recreational areas for people.
They said unplanned rapid urbanization has already taken its toll on the ecosystem of the 400-year-old Dhaka which boasts of a number of cultural relics dating back to the Mughal empire.
"Population boom coupled with unplanned industrialization and urbanization spoiled the urban vegetation of Dhaka," said Mohammad Shakil Akther, an urban environmental expert, in an interview with Xinhua.
Akhter, who teaches at the Bangladesh University of Engineering and Technology, said there should be at least nine square meters of green space in every residence in the city to ensure a healthy life.
But he said this is not the situation in Dhaka where urbanization has not taken into account protection of the environment.
"Global warming has adverse impact on temperature. Trees have played a significant role in cooling down this temperature. That is why we need to emphasize vegetation," Akther said.
Sustainable urban development requires a healthy living environment, Akther said, adding that "trees aside from its aesthetic function can also greatly improve the people's quality of life."
But Akther said that Dhaka authorities are busy providing structural facilities to city residents without considering the need for more green spaces.
"We have no designated corridors for reforestation. Roof- gardens may be a solution but a roof-garden is not suitable for big trees," Akther said. He suggested that the government use road median strips and footpaths for the planting of big trees.
A latest study shows that suspended particulate and ambient sulphur-dioxide levels in the city are about 4 times and 5 times respectively higher than the prescribed levels, owing to lack of vegetation in the city.
According to Akther, Dhaka's internal temperature has increased in alarming rate.In April 2012, the maximum temperature was recorded 41 degrees Celsius. The limited trees in the parks and streets in Dhaka are unable to help infiltrate and recharge required volume of rainwater underground.
"Increased temperature has a vast impact. Top soil is losing moisture rapidly. City's top soil is absorbing rain water before it goes to the underground water. So our underground water is not recharging with rain water due to high temperature," Akther explained.