Dhaka caving in alarmingly as groundwater level falls

With the groundwater level continuing to fall in Dhaka, the land on which the capital city stands has been caving in over the years. This could result in buildings tilting and developing cracks, and putting around 17 million city dwellers at risk of dwindling supply of drinking water. There is a big question mark on the very existence of the city itself. Many parts of the capital are witnessing receding of groundwater level by one to three metres annually. “I have been meeting my water requirement by purchasing it from nearby shops for three days because the water supply at my house has become lesser and irregular. Often we do not get adequate water for drinking after boiling," Didarul Alam of the Hatir Pul area told The Independent. Many people of Kathalbagan, Elephant Road and Baridhara had the same story to tell.
Talking to The Independent, Engr Taqsem A Khan, managing director of Dhaka Water and Sewerage Authority (WASA), said: “Groundwater is being drawn in large amounts, but it is not replenished by an equal amount (of rainwater). This is water mining and can be dangerous as some day the capital could witness landslides.”
Syed Humayun Akhter, professor and chairman of the geology department at Dhaka University (DU), said: “The Curzon Hall area has been subsiding by half an inch annually. In the last 12 years, the area has caved in by six inches. Besides, we observed in satellite images that different parts of the country and areas around Dhaka city are going down by two mm to 16mm annually. The reason is the significant fall in the groundwater level.”
According to the Institute of Water Modelling (IWM), the water table has plunged by 50 metres in the past four decades. The closest groundwater is now at a depth of over 60 metres in many parts of the city. The average groundwater level in Dhaka City was 11.3m in the 1970s, 26.6m in 1996, 28.15m in 1997, 30.45m in 1998, 31.85m in 1999, and 34.18m in 2000.
In the Tejgaon area, the groundwater level is now around 63 metres below the surface and in Mirpur around 60 metres. Experts said the city’s groundwater level is not being recharged despite heavy rain. They blamed the dearth of green land and water bodies in the capital for the situation, which could lead to frequent earthquakes in Dhaka. Talking to The Independent, Quamrul Alam Chowdhury, deputy managing director of WASA, said they had to install new deep tube-wells to meet the increasing water demand. “Almost 78 per cent of the capital’s demand is still met by groundwater. We had no option but to install those tube-wells,” he said.
Admitting the alarming fall of water in the first layer, Chowdhury said the difference between groundwater recharge and extraction rate is also on the rise. “This is happening because some 1,200 illegal deep tube-wells are also extracting water from this layer,” he said. WASA reported that 87 per cent of the water is supplied from groundwater in Dhaka and the remainder comes from surface water treatment plants.  
Water resource and climate change specialist Prof. Ainun Nishat told The Independent: “Most of the surface of Dhaka is coated with a layer of soft clay, which absorbs a good amount of rainwater. So a significant portion of rainwater is lost in the clay surface.” He added that unplanned rapid urbanisation also reduces another significant open space for the rainwater to penetrate into the ground.
He suggested increased dependency on river water instead of groundwater. The rivers around the capital, like the Buriganga, Shitalakhya, Balu and the Turag can be made pollution-free. Once the pollution is stopped, the water can be used, he said.  The water pressure at the second layer or first confined aquifer is dropping significantly with the installation of 64 new deep tube-wells by WASA during the last one year, sources in the water authority said. The water supply authority installed those deep tube-wells to increase its capacity to 248 million litres from 190 million litres. The current daily water demand in Dhaka city is about 220–225 million litres, more than three-quarters of which are met by 679 deep tube-wells across the capital. The WASA, however, said it has taken up a plan for massive recharging of underground aquifers at a minimum cost. It also plans to reduce dependency on groundwater by 50 per cent during the next decade by installing water treatment plants at Khilkhet, Pagla and Saidabad. The second phase of the three-phase Saidabad Water Treatment Plant has formally started operating. It has a capacity to treat 225 million litres of water a day. In rural areas, where farmers now depend heavily on groundwater for irrigation because of silted rivers and canals, it is difficult to operate deep tube-wells due to the fall in the aquifer level. At many places, deep tube-wells set up for irrigation have become totally inoperative. The farmers are, therefore, facing difficulties in maintaining irrigation for growing crops.

Dhaka caving in alarmingly as groundwater level falls

With the groundwater level continuing to fall in Dhaka, the land on which the capital city stands has been caving in over the years. This could result in buildings tilting and developing cracks, and putting around 17 million city dwellers at risk of dwindling supply of drinking water. There is a big question mark on the very existence of the city itself. Many parts of the capital are witnessing receding of groundwater level by one to three metres annually. I have been meeting my water requirement by purchasing it from nearby shops for three days because the water supply at my house has become lesser and irregular. Often we do not get adequate water for drinking after boiling, Didarul Alam of the Hatir Pul area told The Independent. Many people of Kathalbagan, Elephant Road and Baridhara had the same story to tell. Talking to The Independent, Engr Taqsem A Khan, managing director of Dhaka Water and Sewerage Authority (WASA), said: Groundwater is being drawn in large amounts, but it is not replenished by an equal amount (of rainwater). This is water mining and can be dangerous as some day the capital could witness landslides. Syed Humayun Akhter, professor and chairman of the geology department at Dhaka University (DU), said: The Curzon Hall area has been subsiding by half an inch annually. In the last 12 years, the area has caved in by six inches. Besides, we observed in satellite images that different parts of the country and areas around Dhaka city are going down by two mm to 16mm annually. The reason is the significant fall in the groundwater level. According to the Institute of Water Modelling (IWM), the water table has plunged by 50 metres in the past four decades. The closest groundwater is now at a depth of over 60 metres in many parts of the city. The average groundwater level in Dhaka City was 11.3m in the 1970s, 26.6m in 1996, 28.15m in 1997, 30.45m in 1998, 31.85m in 1999, and 34.18m in 2000. In the Tejgaon area, the groundwater level is now around 63 metres below the surface and in Mirpur around 60 metres. Experts said the citys groundwater level is not being recharged despite heavy rain. They blamed the dearth of green land and water bodies in the capital for the situation, which could lead to frequent earthquakes in Dhaka. Talking to The Independent, Quamrul Alam Chowdhury, deputy managing director of WASA, said they had to install new deep tube-wells to meet the increasing water demand. Almost 78 per cent of the capitals demand is still met by groundwater. We had no option but to install those tube-wells, he said. Admitting the alarming fall of water in the first layer, Chowdhury said the difference between groundwater recharge and extraction rate is also on the rise. This is happening because some 1,200 illegal deep tube-wells are also extracting water from this layer, he said. WASA reported that 87 per cent of the water is supplied from groundwater in Dhaka and the remainder comes from surface water treatment plants. Water resource and climate change specialist Prof. Ainun Nishat told The Independent: Most of the surface of Dhaka is coated with a layer of soft clay, which absorbs a good amount of rainwater. So a significant portion of rainwater is lost in the clay surface. He added that unplanned rapid urbanisation also reduces another significant open space for the rainwater to penetrate into the ground. He suggested increased dependency on river water instead of groundwater. The rivers around the capital, like the Buriganga, Shitalakhya, Balu and the Turag can be made pollution-free. Once the pollution is stopped, the water can be used, he said. The water pressure at the second layer or first confined aquifer is dropping significantly with the installation of 64 new deep tube-wells by WASA during the last one year, sources in the water authority said. The water supply authority installed those deep tube-wells to increase its capacity to 248 million litres from 190 million litres. The current daily water demand in Dhaka city is about 220225 million litres, more than three-quarters of which are met by 679 deep tube-wells across the capital. The WASA, however, said it has taken up a plan for massive recharging of underground aquifers at a minimum cost. It also plans to reduce dependency on groundwater by 50 per cent during the next decade by installing water treatment plants at Khilkhet, Pagla and Saidabad. The second phase of the three-phase Saidabad Water Treatment Plant has formally started operating. It has a capacity to treat 225 million litres of water a day. In rural areas, where farmers now depend heavily on groundwater for irrigation because of silted rivers and canals, it is difficult to operate deep tube-wells due to the fall in the aquifer level. At many places, deep tube-wells set up for irrigation have become totally inoperative. The farmers are, therefore, facing difficulties in maintaining irrigation for growing crops.