By Ashiqur Rahman
As the Dhaka Water and Sewerage Authority (Wasa) digs deeper into the ground in search of extractable water, as part of a new high depth tubewell initiative, the consequences for the environment and the public are becoming more and more grave, a WASA official and an expert warned.
Dr ANH Akhter Hossain, Managing Director of Wasa, said a total of 10 tubewells of a 1,000-foot depth have already been installed recently in the city's Mirpur area, with 35 more to be installed in the near future.
Wasa authorities have been compelled to undertake such an initiative because the existing 1,500 wells, whose depth reaches only 600 feet, can no longer extract water due to a serious depletion of the underground water level, he pointed out.
Other Wasa officials have asserted, however, that Wasa will not be able to keep the number of 1,000-foot tubewells under 45, and may continue to increase the number by an indefinite amount in the future.
The move has caused concern both within and outside of Wasa, with officials of the water authorities as well as experts saying it could have a destructive impact on the environmental conditions of the city.
Professor Nazrul Islam of the Department of Geography and Environment at Dhaka University, says Wasa should avoid ground water extraction and search for surface water sources in order to save the groundwater environment. 'Presently, only 25 percent of the water is collected from surface water sources, but this should be significantly increased on a priority basis,' he said.
Relying on groundwater extraction alone poses a grave threat to land subsidence, with a potentially negative impact like that experienced in countries like Bangkok and Mexico, he said. 'Two decades ago land subsidence of a few inches took place every year [in those countries] due to unbridled groundwater extraction.'
A high official and expert within Wasa, who spoke on the condition of anonymity, cautioned that Wasa should have conducted a study to determine whether city dwellers will actually benefit from the installation of the 1000-feet deep tubewells.
While the benefits remain uncertain, the results to the environment could be seriously harmful, he explained.
'The initiative to set up 1000-feet depth tubewells in the city is very destructive since existing 600-feet deep tubewells have already created a large vacuum within the underground level due to a lack of water recharge, making the situation very vulnerable to earthquakes,' he asserted.
He went on to say that increasing the number of high depth tubewells in the city may be an immediate solution to the water crisis, but that it will boomerang in the long term for the city dwellers, causing natural disasters.
'Finding no other alternative, Wasa authorities have undertaken the initiative as a short time solution due to the government's failure to assemble funds to increase surface water sources,' he asserted.
Acknowledging the adverse impact of unabated ground water extraction on the environment, Akhter Hossain said, 'We definitely want to create more surface water sources instead of increasing the number of deep tubewells in the city.'
The Danish International Development Agency (Danida) and the Swedish International Development Agency (Sida) are expected to give financial assistance to complete the second and third phase of Saidabad Surface Water Treatment Plant which will largely meet water demands of the city dwellers, he added." (C) The Daily Star, Bangladesh.