The level of groundwater in Chattogram and its coastal areas with dense industrial factories has dropped by as much as two and a half metres a year, a study shows.
Experts and authorities have suggested reducing the use of underground water to avoid environmental risks.
The calls came on World Water Day, which is held on Mar 22 every year to celebrate water and raise awareness of the two billion people living without access to safe water.
The slogan for this year's World Water Day is 'groundwater, making the invisible visible', with a focus on researching groundwater, conservation and the environmentally friendly usage of water.
Dr Aysha Akter, head of Water Resource Engineering at the Chittagong University of Engineering and Technology, and Missouri State University researcher Shawkat Ahmed have conducted a lengthy study of water levels in 22 Chattogram city wards. The research was conducted in two phases, the first from 2009 to 2016, and then again from 2020 to 2021.
The groundwater level is gradually dropping in seven wards - North Pathantuli, North Agrabad, Rampura, South Agrabad, Pathantuli, West Madarbari and East Madarbari, said Ayesha Akter.
The level has dropped by 2.2 to 2.65 metres every year. In 2020, the water level was 102 to 352 feet underground in these areas.
The number of privately installed deep tube-wells has increased, said Mohsin Kazi, former board member of Chattogram WASA. “As people are not getting enough water from WASA, they’re depending on deep tube-wells and that is one reason the groundwater level has dropped.”
Plastic pollution is another reason for water scarcity as it prevents water from entering the ground, said Dr Suman Barua of the Department of Applied Chemistry at Chittagong University.
“In some parts of the city, the groundwater is 600 to 700 feet underground. This is really alarming. We need a full survey to understand the full scope of the issue and to take the necessary steps.”
In Mirsarai and Sitakunda, two areas with dense industrial areas, the groundwater level has dropped so sharply over the past few years that shallow tube wells are unable to pump up water. Now locals have been forced to install deep tube wells.
The Department of Public Health Engineering works to set up deep tube wells in Chattogram city and its Upazilas. Five years ago, a tube-well installed at 15 to 20 feet deep could yield safe drinking water in some areas, including Sitakunda and Mirsarai, said Sumon Roy, an executive engineer, who oversees the department's Chattogram circle.
Now the tube-wells must be at least 30 feet deep in the ground to get drinking water.
"Hand pumps or shallow tube-wells cannot provide water in the dry season anymore. We are no longer installing hand pumps. Instead, we install submersible pumps that can go up to 100 feet for housing to ensure people get water throughout the year," he said.
The agriculture and industrial sector use a large quantity of water, and that is the main reason behind the dip in groundwater level, said Roy.
"Sometimes, when a production tube-well is operating in one place, the groundwater within an entire kilometre dries up."
On May 30 last year, locals in Sonapahar of Mirsarai Upazila took to the streets when they lost access to water after a steel factory-installed deep tube wells in the area.
Shallow pumps in some unions, including Hinguli, Jorarganj, Sonapahar, Dhum, Osmanpur, and Durgapur, cannot pump up water, said Rajib Majumdar, a resident from Jorarganj. In some cases, privately installed tube wells were able to pump up water only when they could reach 500 feet below ground.
"Newly installed tube-wells can get water, but not the older ones. The reality is that the groundwater level has been dropping,” said Jorarganj Union Council Chairman Rezaul Karim.
“Hopefully all the new factories will be set up in Bangabandhu Industrial City once it opens and not in our neighbourhood. But research is needed to determine why the water level is dropping.”
DEEPER GROUNDWATER LEVEL, SALINITY IN COASTAL AREAS
Officials at the Department of Public Health Engineering said that freshwater has been found 800 to 1,200 feet underground in Banshkhali’s Sarol and Gondamara unions. Also, some tube-wells installed in Anowara Upazila near Parki Beach pump up saltwater. Patiya and Banshkhali have groundwater levels 30 feet deep.
Milan Kumar Chakraborty, a former senior chemist of WASA, said that the over-pumping of water could be the cause of the drop in water level.
“There could be other reasons too. Information about static water levels may help us to identify the true cause and understand the situation. Sitakunda and some other coastal areas already have a salinity problem. As freshwater levels underground drop, it may be replaced by saltwater.”
CHATTOGRAM CITY SUFFERS AS WELL
DPHE engineer Sumon Roy said they had to dig below 500 feet while installing a deep tube well in Pachlaish last year.
“In most parts of the city, the water level is about 100 to 200 feet underground. But it’s also very hard to get groundwater in Pahartali.”
USE LESS GROUNDWATER
The continuous use of groundwater could cause the water level to drop further, said Aysha Akter.
It would increase the cost of water pumping and also salinity and water bodies would be lost, she said. The effects on the environment, both direct and indirect, would be significant.
Groundwater prevents earthquakes and therefore its level must be maintained, Prime Minister Sheikh Hasina said in a speech on Mar 16.
She instructed industrial factories and real estate project authorities to reserve water from natural sources and to build reservoirs.
Groundwater levels should increase when rainwater seeps through, said former WASA official Milan Kumar. As Chattogram city suffers from uncontrolled infrastructure construction, the rainwater cannot pass through the ground. Therefore, all structures and open spaces should have a provision to store rainwater.
“Ponds and other water bodies are filled and the rainwater ends up flowing out to sea through the rivers as it can’t pass through the ground. Thus, the quantity of freshwater is reduced and the level drops.”
As an alternative to groundwater, people should use rainwater, Dr Aysha Akter suggested.
“To reduce salinity and pollution, water can be sent to the ground through artificial means. Also, rainwater can be used for household chores, car washing or flushing the toilet.”
Chattogram WASA claims it is currently producing more water than is in demand. If that is so, the institution should close deep tube-wells, said former board member Mohsin Kazi.
When asked, Md Nurul Amin, supervising engineer of Chattogram WASA, said they stopped operating most of the deep tube wells and the rest will be stopped soon.
Authorities in some municipality areas have started to use surface water, said Sumon Roy. Also, a project is working to supply water from the Sangu River after treatment, he said.
But usage of river water in the agricultural sector is a must to save groundwater, he believes.
Dr Aysha Akter said a review of the policy that allows groundwater use in the industrial sector is needed.