Dhaka is a megacity in Bangladesh, home to 14.73 million residents, and houses thousands of industries, according to BBS’s Population and Households Census 2022. With a population density of 10,067, this number could double during the next 10 to 15 years due to rising rapid urbanization and fast migration.
This unregulated urbanization produces a variety of issues. Once widely abundant, groundwater depletion is one of the most pressing challenges as it continues to deplete dramatically and may disappear far below the ground.
However, we rarely prioritize it. Many do not understand where their water originates, groundwater levels, or what would happen if it disappeared.
The water sources supplied in Dhaka are groundwater and surface water. Around 67% of water comes from underground sources, and the rest, 33% from surface water.
If we take into account the industrial situation, it portrays a mere scenario to us. Dhaka and the nearby industrial areas are facing the same crisis, including Narayanganj, Narsingdi, Gazipur districts, etc.
For example, an industrialist, Fazlee Shamim Ehsan, recently faced a groundwater problem in his apparel factory, Fatullah Apparel Limited.’ Two out of three pumps of Ehsan’s factory suddenly went out of service to lift the groundwater.
“It was out of reach of the existing water layers, so I had to use a 200-foot pipe into the boring pump,” explained Ehsan, managing director of Fatullah Apparels Limited.
“It’s a concern for us (industrialists) since it has increased production costs. How would we manage groundwater as entrepreneurs if it becomes more expensive in the future,” he questioned.
Currently, the number of deep tube wells is around 900, through which the groundwater is abstracted and supplied. There are five water treatment plants in different parts of the city. The water of the rivers Shitalakhiya, Buriganga, and Padma are being treated and supplied in the city.
Dhaka WASA is currently capable of producing 2.65 billion liters of water daily against the daily demand of 2.50-2.55 billion liters from the existing available infrastructures and installations, according to the annual report of Dhaka Water and Sewerage Authority (WASA) from 2021-22.
This dependency on groundwater over a long period has taken a toll on the groundwater level in Dhaka.
“People in Dhaka are extracting water from the ground at a very high rate, and this extracted amount is not being restored naturally and artificially,” commented Syed Mohaiminul Islam, who is currently pursuing an MSc in Water Resources & Environmental Management at Leibniz University Hannover with Major in Sanitary Engineering and research background in Urban Hydrology.
“This has led to a significant drop off of water level,” he said.
Quoting the 2030 Water Resources Group, Mohaiminul Islam said Dhaka city’s annual water decline rate is 3 meters.
“If the demand increases, which is likely, then this can reach up to 3.9 meters annually this year and 5.1 meters per year in 2030. If any preventive measures are not taken, groundwater levels will fall to 100 to 150 meters by 2050.”
He said that the groundwater that we are blessed with and continue to use comes from the rainfall, which we see, and the flow of water underground from higher elevation to lower elevation, which we can’t see.
He added that aquifer is the correct term to describe these large bodies of water between sand and clay particles that have formed over the century.
“The flow of groundwater is very slow, and once these aquifers are dried out, they take centuries to be restored.”
Dhaka, with its low unpaved area, has limited natural groundwater recharge. This dependency on rainwater makes it difficult for the deep aquifer to hold onto its limited water. Groundwater weighs down the Earth’s upper crust.
The crust is lifted if the groundwater falls below a certain depth. This shift aggravates the fault line, which can trigger earthquakes in the area.
“If groundwater level drops by a certain depth, it can be one of the major causes of an earthquake. A major earthquake of 7.0 magnitude on the Richter scale will cause havoc in a congested city like Dhaka and cost many lives,” said Mohaiminul, quoting a paper by Colin B. Amos from Nature Journal.
If we want to achieve our goals, we have to deal with the major groundwater problems that we are on the verge of facing.
Cape Town, South Africa, in 2018, faced a day zero situation when the city was days away from being the first city in the world to run out of water.
Day Zero: What happened at Cape Town?
In South Africa, ‘Day Zero’ refers to the hypothetical day a city or region’s municipal water supply is predicted to run out. It received widespread notice during the catastrophic drought that struck Cape Town from 2015 to 2018.
The city’s water supply may run dry due to little rainfall, excessive water demand, and ineffective water management.
During the drought, Cape Town implemented rigorous water restrictions, public awareness campaigns, and infrastructure projects to conserve water and postpone Day Zero. These measures included limitations on water consumption for families, businesses, and agriculture, as well as steps to reduce leaks and enhance water recycling.
Fortunately, citizens and the government worked together to prevent Day Zero in Cape Town. However, the experience demonstrated the vulnerability of South Africa’s water resources and the significance of long-term water management methods in the face of climate change and demographic increase.
Can Bangladesh avoid such a crisis – What do experts say?
Although Bangladesh and South Africa do not have the same climate areas, we must be careful to use groundwater,” said Chairman of Evince Group and former president of BGMEA Anwar-Ul Alam Chowdhury (Pervez).
“Industries, who used to spend more water, must move on the zero discharge,” he said.
Initially, businesses must use ETP to reuse water and avoid wastage, according to Mr. Chowdhury, the president of the Bangladesh Chamber of Industries (BCI). He also urged the government to make a central ETP in industries-prone areas through a meter system.
Dr. Abu Hena Md Zulfiquar Ali, professor of the Department of Soil, Water & Environment at the University of Dhaka, urged raising awareness among the residents and industrialists.
“We have not yet reached the critical stage. But the country has to be aware of its loopholes in groundwater distribution,” he said.
Professor Dr Adil Mohammed Khan, president of the Bangladesh Institute of Planners (BIP), suggested taking measures to combat groundwater depletion and improve water supply management for Dhaka city.
“We have to ensure the acceleration of the use of surface water and reduce the dependency on groundwater, and the illegal extraction of groundwater should be punished,” said Mr. Khan.
He also said the unauthorized deep-tube wells for industries and residential buildings should not be legalized. The water pollution of the rivers, canals, and water bodies should be controlled, and polluters should pay polluters fees and be adequately punished.
To avoid such a Day Zero situation, the country needs to take urban growth management policies to limit the growth of Dhaka city and density control mechanisms.
“Unauthorised industries should not be allowed to be formed to reduce industrial water demand, and the government capacities of WASA, RAJUK, City Corporation, and other related urban bodies should be significantly improved for proper water management.”
“Some short-medium- and long-term planning with appropriate actions should be formulated to combat groundwater depletion and efficient water supply management for Dhaka city,” Professor Dr Adil Mohammed Khan added.
Mohaiminul Islam also stated that water extraction causes empty areas, which leads to compaction and settlements, and if this occurs, sinkholes may emerge, or fault lines are nearby, they may be affected, triggering earthquakes.
Research has been conducted worldwide to investigate the relationship between seismic activity and a decline in groundwater levels.
“We all know how congested Dhaka is and how severe earthquakes may cause casualties.”
“We have to increase this infiltration rate. Concepts of using Bio-retention cells, rain gardens, and permeable pavements can increase the groundwater recharge rate. Implementing Bio retention cells, Rain Gardens, and Vegetative Swells also increases the amount of green space Dhaka is missing,” he remarked.
The concept is already being used in Germany, the USA, and China. Rainwater Harvesting is also a very popular concept, which looks to collect and store rainwater for further usage, he said.
Md Asaduz Zaman is a Bangladeshi journalist who covers Bangladesh’s economy, environment, and agriculture sectors. He can be reached at: mazamanstar@gmail.com