The annual daytime temperature in Dhaka city has risen by about 4 to 5°C in the last couple of years while the world is struggling to keep global temperature increase below 1.5°C.
Temperature rise is among the major consequences of shrinking wetlands in Dhaka, capital of Bangladesh. All kinds of wetlands in the city are disappearing or shrinking rapidly. As a result, the temperature is rising at an abnormal rate.
Many areas of Uttara, Khilkhet, Mirpur, Bosila, Banasree and some other areas of Dhaka city have been developed in the last couple of years by filling up wetlands. Even some of the areas have been entirely developed by filling up wetlands fully.
If the trend of housing projects in Dhaka city continues in the way that was done in the last few years by filling up wetlands, it will be difficult to find wetland in the city in a few more years, or there will be very few wetlands.
Mohammad Azaz, a researcher on river and wetland, thinks that if this happens, the temperature of Dhaka city will increase at an abnormal rate.
Talking to Bangladesh Post on Friday (February 10), Mohammad Azaz, chairman at River and Delta Research Centre (RDRC) said that although housing projects in the city were developed by filling up wetlands, there are still some wetlands here. “We have to save the rest of the wetlands if we want to survive here,” he said.
In 1990, wetland consisted of over 11 per cent area of Dhaka city. Now the wetland has reduced to less than five per cent. The temperature of many areas of Dhaka city was 15-18°C at that time. Experts said that the rise in surface temperature contributes to an increase in overall temperature of the city.
“The average temperature in Dhaka city was 27°C about 30 years ago. Currently it has increased to 32°C. The situation has arisen mainly due to housing projects by filling up the wetland, which keeps temperature normal. If the trend of filling the ponds, canals and other wetlands continues, the average daily temperature will stand at 50°C after a few more years, in which it is impossible to survive,” said Mohammad Azaz.
No more wetlands should be filled up further to avoid deadly temperature, he suggested.
Wetland is very important for environmental and ecological balance. The wetland plays a vital role in water management as the wetland interacts with groundwater and surface water also for fresh water supply. The wetland also plays a vital role for greenery and conserving biodiversity.
“Without wetlands there is no biodiversity, the balance of the environment is completely destroyed. Destroying wetlands also triggers many health concerns of the citizens,” said Muhammad Anowarul Hoque, secretary general at Save Our Sea.
Not only in terms of temperature, rapid disappearance of wetlands is a major reason behind the increase in dengue prevalence and mosquito menace in Dhaka city. The Aedes mosquito-borne viral disease has become a grave concern for the city dwellers.
Although alongside the drains and dustbins, the water bodies are being considered as the breeding grounds for Aedes mosquito, this would not have happened if the wetlands had been adequate.
The two city corporations of Dhaka have taken some strategies against the mosquito menace to prevent dengue. Releasing frogs in ponds by the city authorities as well as farming frogs, ducks and fishes in water bodies is one of the strategies to destroy mosquitoes and their larvae.
Talking to Bangladesh Post, Muhammad Anowarul Hoque of Save Our Sea said, “Frogs are no longer seen in the city as wetlands have receded and existing wetlands have been shrinking. Frog mainly eats mosquitoes. If there were adequate wetlands like before, there would be a lot of frogs. As a result, mosquito menace would also be reduced and dengue outbreaks would not occur.”
Most of the wetlands, including ponds and canals, disappeared from Dhaka city only in the last 20 to 30 years. However, at least one-fourth of wetlands in Dhaka city were lost in the last ten years. On the other hand, two per cent of the wetlands of Dhaka are occupied illegally every year.
Alongside the grabbing, rapid growth of population, high presence of arsenic, salinity in water, presence of dust and particles in the air and temperature rise are among the consequences of shrinking wetlands in Dhaka city.
The city once had many ponds. Now there are only a few ponds in the city. Mohammad Azaz of RDRC said that they have found only 350 ponds in the city.
As per the law, filling of ponds and any other is a punishable offence. Hundreds of ponds and many other wetlands have been filled up in the past few years, but no relevant authorities have been heard to take action in this regard.
Syed Saiful Alam Shovan, a rights activist who has been fighting for years for ponds and wetlands, reacted angrily over the issue. Although he wrote and complained to the Department of Environment (DoE) and other bodies concerned many times about the various ponds and other water bodies in Dhaka city, the DoE or any others never played an appropriate role to save ponds or any other wetland.
Although Mohammad Azaz said Dhaka city now has 350 ponds, Syed Saiful Alam Shovan said that that was much less. “Maybe there are 350 ponds on paper. In reality, however, far fewer ponds exist in Dhaka city. We should raise our voices to save the ponds. Youths’ involvement in this regard is needed,” he added.
Syed Saiful Alam Shovan also came down heavily on the National River Conservation Commission (NRCC) and the Dhaka Water Supply and Sewerage Authority (WASA). The High Court has identified the NRCC of Bangladesh as legal guardian for all the rivers and other water bodies in the country. But the NRCC doesn't play a role in this regard. On the other hand, the WASA destroyed many wetlands in the name of development, drains and sewerage lines, he alleged.
Mohammad Azaz, Muhammad Anowarul Hoque and Syed Saiful Alam Shovan called for preserving the wetland to address the future challenges of climate change.
