Inadequate number of water bodies in the city creates crisis of surface and groundwater, increase heat, makes rainfall uneven and disrupts the overall eco-system of the city, the experts pointed out while talking to Star City.

Ashraf Mahmmood Dewan, a professor of the Geography department of Dhaka University, said the city should have at least 25 percent of its area in water bodies.

But a recent survey under the Dhaka Environment Project conducted by the Department of Environment reveals that the city has four percent of its area in rivers and another four percent in water bodies.

Prof Ashraf also said lack of water bodies would increase flood risks and hamper recharging of groundwater and retention of flood water.

"Water bodies retain surface water. But now it has become difficult in the city," he said.

Golam Rabbani, senior research officer of Bangladesh Centre for Advanced Studies, said rivers around the city have been polluted dangerously, creating huge pressure on groundwater for household use.

"The groundwater table of the city is going down by up to one metre a year," he said.

Rabbani said water bodies in the city are being filled up increasingly, posing a serious risk of water crisis in near future.

In Dhaka, the daily water demand is about 200 crore litres while the production capacity is 180 crore litres. The average supply is 164 crore litres, according to Dhaka Wasa data.

Dhaka Wasa runs four water treatment plants that are using surface water and supplying 18 percent of the total supply. Rest of the water supply comes from groundwater through 430 deep tube-wells, according to the Wasa data.

The Dhaka Environment Project is to be implemented over a period of 20 years with an investment of $8 billion. The surveys under the project, conducted between May 2003 and September 2004, showed the metropolis had 67 square kilometers of water bodies and 64 square kilometres of rivers.

The project pointed out that the main challenges of the environment of Dhaka and said that at least 80 per cent of the sewage produced by the inhabitants of the city goes into the river system untreated. Almost all of the estimated 7,000 industries in Dhaka and its outskirts discharge their waste directly to drainage ditches, khals and the rivers.

Moreover, encroachment on rivers, khals and other water bodies is restricting the flow in the rivers around Dhaka and reducing flood-buffering capacity.

Imamul Haque, director of Bangladesh Haor and Jalashoy Board, said due to filling up of wetlands and water bodies, evaporation rate of water reduces that ultimately leads to imbalance in the quantity of rainfall.

Ferdousi Begum, a plant biologist and executive director of the Development of Biotechnology and Environmental Conservation Centre, told Star City that filling up of water bodies is playing significant role in unbalancing the environment.

Akkas Ali, who is planning to build a multi-storey building filling up a pond at Mirpur, told Star City on Monday, "I don't know what are the impacts of land filling. I don't want to know the rules when no one is abiding by the rules even to save wetlands."

Experts said alongside public awareness, full implementation of the existing laws for saving water bodies could avoid the dire consequences.