Detailed Area Plan (DAP) would have to be included existing low-lying wedands as well as revival of the pre-urban wetlands to ensure environmental sustainability of the city, said an expert.

“Immediate attention is needed for wetland preservation and reviving them for keeping Dhaka city liveable,” said Dr Mohammed Ataur Rahman, director of the Centre for Global Environmental Culture (CGEC) Programme on Education of IUBAT.

He said revival of wetlands would restore and rehabilitate the flora and fauna, mitigate acute water crisis of the city, recharge ground water and revive the wetland ecosystem.

“With the revival of wetlands, the city will be free from water stagnancy and flooding while this will facilitate the communication system — both waterways and road transportation system."

He noted that the Ramsar Convention has defined wetlands as areas of marsh, fen, peat land or water,

whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salt, including areas of marine water the depth of which at low tide does not exceed six meters.

Dr Ataur said Dhaka with an aerial extent of 298 square kilometer is bounded by the river Buriganga in the south, the river Balu in the east, the Tongi Khal in the north and the river Turag in the west. These rivers are connected to the Ganges-Brahmaputra River system and also include the Old Brahmaputra river flowing towards southeast horn all sides of the bigger neighboring region.

The bigger area is closely dissected by a number of rivers and khals which are hydro-logically connected to these major rivers, he added.

Dr Ataur said wetland of the city has been squeezed to five percent only, resulting in acute shortage of surface water supply.

Pollution has become a great threat for the existence of aquatic lives.

He said the inland water bodies on the aerial photo of 1968 are more prom-

inent than 2001. Analysis and observation for inland water body on 1968 image show that the Gulshan Lake, Dhanmondi Lake and Ramna Lake are highlyvisible.

He noted that the total areas of inland water body are measured 5.1 square kilometer. Analysis of satellite image of 2001 for inland water body shows that the areas of lakes (Gulshan and Dhanmondi) have shrunken and narrowed down.

“Some khals and channels are not identifiable or missing in the southwestern Mohammadpur and southern Motijheel area of the city and the total area is measured 1.8 square kilometer in2001,”hesaid.

It is seen that water bodies have become more sporadic and patchy in 2001 in comparison to 1968 in many parts of the city. Water body compart-mentalisation, specifically, occurred in the north central, southeast and western part of the city.

He said canals, wetlands and depressions have been filled up by new urbanisation, both in and around the built-up city area. These unplanned

urbanisations have been destroying the water bodies and flow paths causing rainfall-flooding and drainage congestion in many locations in the city.

Filling activities, embankments and roads are compartmentalizing the wetlands and water bodies and hence obstructed the natural drainage.

Dr Rahman said the wetlands and other water bodies in the city is greatly reduced over the decades due to progressive urbanisation.

There were number of studies that mentioned the land filling activities and their effects on the drainage congestion and waterlogging.

At the moment, the city gets waterlogged, particularly during the heavy downpour in the wet season. The scenario will worsen with time as erratic and intense rain occurs with increasing frequencies due to climate change.

Plants and soils in wetlands play a significant role in purifying water, removing high levels of nitrogen and phosphorus, and in some cases, removing toxic chemicals through biogeochemical cyclingand storage, hesaid.