The New Nation - Internet Edition

AS reported in the media quoting a recent study, the ground water level in Dhaka is dipping because of a massive extraction. Posing serious threat of land subsidence experts warn, the groundwater level is declining by up to three metres every year. The extraction caused a sharp drop leading to two cones of depression in water level and the upper parts of the aquifer are dewatered throughout the area, except for swathes of northeast and southeast corners, says the study that was carried out jointly by experts and academics.

How fast the dewatering process deep under the surface worked due to the massive extraction of water from underground is revealed by the study that says about 4.1 crore cubic metres of the aquifer dewatered until 1988, which increased to 227.2 crore cubic metres in 2002. The groundwater level was declining at an alarming rate and dewatering was spreading to the adjoining areas too. Dewatering widened by as much as 55 times in 20 years and experts stressed increasing the use of surface water to cut pressure on groundwater. According to the information of the Dhaka Water Supply and Sewerage Authority, upto 180 crore litres of water is pumped out in Dhaka and Narayangonj every day though the demand for water in both the places is much higher for meeting the daily requirements.

Meanwhile, the use of surface water has begun and under a plan it has been decided to use 100 crore litres surface water a day by 2015 with a view to reducing the pressure on groundwater as its level has been dropping alarmingly. There are about 2,000 deep tubewells operating in the capital - 800 out of them with WASA-approval. About 85 per cent of the WASA's water comes from underground sources and the remaining 15 per cent from surface water.