Things that make you to Think
The scarcity of clean and drinking water in the capital is a hot topic in both the print and electronic media ahead of summer every year. However, such extensive discussions on the problem have not yet managed to evoke an alarm among the ‘concerned’ authorities to bring out a long-term solution. Even worse is the fact that, due to the excessive extraction of ground water and acute pollution of the surrounding rivers of the capital, the GW level has dropped down from the mean sea level (MSL). Global warming and climate change are also playing their parts to elevate the trouble for city dwellers.
The crisis is not confined to the capital and is slowly spreading throughout the country. However, it is most acute in the capital, which houses a total of 8,511, 228 people, according to the 2011 Census of Bangladesh Bureau of Statistics (BBS); the actual number is suspected to be much higher.
The adverse impacts the unplanned withdrawal of ground water, besides climate change, have now grown to be the most dangerous threat to the life and livelihood of about 60 million people as well as the flora and fauna in the Southern part of Bangladesh, as stated by a report by Bangladesh Agricultural Development Corporation (BADC) published in November 2011.
There are two more dangerous threats that are silently looming above our head: one, the underground saline water intrusion approaching inland from the Bay of Bengal, and two, the declining of Dhaka city’s ground surface every year at an alarming rate.
The state of the underground
Once, it was considered that there is a large underground water reserve in our resourceful country. This assumption was correct to some extent, but due to unplanned withdrawal and dependence on ground water, the situation has grown morose and threatening for our next generation.
In Dhaka city alone, the daily demand for fresh water is 2.1-2.25 billion litres in 2012, which was 1.5 billion litres in 2000 and 1 billion litres in 1990, according to Dhaka Water Supply and Sewerage Authority (WASA). “To fulfil the demand of the city’s domestic, industrial and commercial purposes, WASA has 602 deep tubewells and four water treatment plants that can produce and supply the demanded water,” said Eng Taksim A Khan, managing director of WASA, in a press conference this month.
However, he also said that about 10,676 new water connections were given within the past one year, and WASA currently has a total of 302,513 water connections. 87 per cent of the high water demand is met with ground water, while the remaining 13 per cent comes from the surface water from the Rivers Buriganga, Shitalakkha and Balu. The river waters is treated in the water treatment plants, but due to the excessive pollution and rising demand of fresh water, WASA needs alternative sources of surface water immediately.
The high rate of ground water withdrawal causes decline of water level at an average rate of 1.5-3 metres per year around Dhaka city, says WASA officials, adding that the static water level across the city is not the same. For example, from the latest recorded data, the ground water level is at 80 metres in Niketan, 77 metres in Khilgoan, 42 metres in Dhanmondi, 40-49 metres in Gulshan, 47 metres in Mirpur Pirerbag, 70 metres in Bashabo-2, 61 metres in Arambag, 68 metres in Madartek and 43 metres in Mirpur Sheorapara.
However, the GW level of Dhaka city has been already gone 53.18 below the MSL, reports BADC. The report also discloses the other district’s GW depletion below the MSL
|Depletion below MSL|
|1.||Netrakana||Atpara, BarhttaSadar, Purbadhala||6.11-8.35m0.70-2.96m|
|3.||Mymensingh||Dhobaura, Fulbaria, Haluaghat, Iswargonj, Nandail, Trishal||5.00 -7.00m|
|Savar||2.00 – 5.14m|
|6.||B. baria||Nabinagar||0.50- 2.00m|
|7.||Comilla||Brahman Para, Chandina, Chauddagram, Debidwar, Laksham, Muradnagar||0.55 – 2.00m|
|8.||Jessore||Bagerpara, Sadar, Chaugachha, Monirampur, Jhikargachha, Sharsha||0.00 – 1.00m|
Researchers and experts have expressed their deep concern over these alarming facts. According to BADC, underground salinity has reached Tungipara in Gopalganj district coming from the country’s coastal areas.
In the meantime, the capital’s earth surface is dwindling by 12.64 millimetres and ground water level is declining three metres per year, as Professor Syed Humayun Akhter, director of Dhaka University Earth Observatory (DUEO), said in one of his reports. He found this data using Global Positioning System (GPS), and said that “this is causing a vacuum below the ground”.
“Bangladesh is a part of a delta and Bengal basin. The main reason of dwindling of the basement of Bengal basin is unplanned ground water extraction, and the tectonic movements and siltation are also responsible,” he pointed out.
“There are more than 2,500 deep and shallow tubewells in Dhaka city. At present, around 2.5 billion litres of ground water is extracted every day through those sources, which was 1.5 billion litres in 1998. Due to the excessive extraction, the ground water level is declining quickly. It is below 68 metres today, whereas it was within 10 metres in the 1970s,” he added.
“The alluvial aquifers which are saturated with water; due to withdrawal of water those aquifers are being vertically narrowed through water withdrawing. Thus in that levels sand become narrowing by reconstruction. It is found that, which layer was 1m portly that is now less than 1m by narrowing. But there are some levels with silt and mud. This mud levels are being narrowed if water is removed from it for which those the GW table is declined and at the same time the surface of the earth is dwindled too,” he said.
Causes and threats
According to the water experts, geologists and hydrologists, the main reason behind such terrible situation is because the vacuum caused by ground water extraction does not get refilled as necessary. Much dependence on and unplanned withdrawal of ground water, as well as the misuse of water are the human causes, as experts think, while climate change, less rainfall, less duration of flood and rainfall, decrease of water discharge in trans-boundary rivers are the natural causes.
“At present, we extract about 53bcm (billion cubic metres) ground water for irrigation purpose across the country, but the water ‘recharge’ is less than 52bcm,” said Dr Eftekharul Alam, agriculture, water and environment engineer and specialist at BADC.
Unfortunately, no accurate data was found regarding ground water extraction for industrial and commercial purposes. “If we consider the water usage at industrial and commercial levels, then the shortage in ground water level will measure even more,” Dr Alam added.
“In 1960, our food production was 8.45 million MT (metric tonnes), which grew to 33.5 million MT in 2011. The ever-increasing demand for food put a stress on our irrigation sector. Boro rice was produced at 400,000 MT during the 1960s, and now more than 10 million MT are produced. Naturally, more water is required for the irrigation,” he said. This is just one example of the growing demand for water.
During 2009-2011, BADC measured the latitude, longitude, reduced level (RL) and ground water levels of the observation wells all over the country by using RTK GPS. “Out of the 3,166 observation wells, 416 wells’ ground water levels have gone down below the MSL, and those wells have not been refilled with water since 2004,” said Dr Alam, who is also the chief of Minor Irrigation Information Service Unit (MIISU).
These wells are mainly in Netrakona, Kishoreganj, Jamalpur, Tangail, Mymensingh,Gazipur, Manikganj and Comilla districts. All of them are separated from each other as well as far away from the Bay of Bengal. The BADC report, prepared by Dr Alam, notes that before 2004 the underground vacuum in Dhaka city was recharged by the water flowing from the North, i.e. the aquifer of Gazipur district and its adjoining areas. At present, however, these areas are suffering from severe ground water depletion, as the report remarks, and the only way for the vacuum to be recharged with water is to store the saline water flowing from the South due to the now-high MSL, except in the rainy season.
It also must be mentioned that water restoration in Dhaka’s underground does not occur adequately because of the rapid and unplanned urbanisation, which is causing decline in the number of canals, ponds, lakes, etc as well as acute river pollution. Water wastage is also a big issue.
A WASA official said, “There were 43 canals in the master plan of Dhaka city, but now about 16 of them exist.” “If this situation persists, then soon the ground will not be able to support all the infrastructures and they will collapse. The sewerage system will also be destroyed, and roads, gas and water system will crumble,” said Professor Humayun Akhter.
“Buildings have collapsed due to underground vacuum in Dhaka before: at Kalabagan in 1995 and at Bashabo’s Jheelpar in 1997,” he shared, adding that, it was also one of the prime reasons that caused the leaning of buildings at Begunbari, Nakhalpara, Gendaria and Mirpur.
Saline water intrusion and its effect
Another crucial threat is saline water intrusion from the Bay of Bengal to the inland due to the dwindling groundwater level. Dr Eftekharul Alam addressed this problem, “The flow of underground water is from North to South. This flow prevents the access of salt water invasion. Now, if this ground water flow declines due to excessive mining, then saline water will get more access to the inland from the Bay of Bengal. This intrusion occurs during December-May period, and is unstoppable now.”
“We have found saline water 1,100 feet below the surface in Gopalganj district. In some areas, salinity has been found at 100-150 feet through shallow tube wells,” said Anwar Zahid. The underground saline water intrusion has mainly resulted from unplanned water withdrawal in Madhupur and Burind tract, the country’s major areas of recharge.
The effect of saline water intrusion is much worse, dangerous and destructive than any other natural disasters. Natural calamities are visible and start at a particular time and stop automatically after a certain period. Underground saline water intrusion, on the other hand, is difficult to detect; it is tough to pin point exactly when it is going to start or started, its present condition and how far it may advance, without conducting surveys using advanced technical instruments and experiments.
“Once saline water intrudes the underground of Dhaka, it will take more than 100 years to remove the salinity, even after using the best cutting edge technology,” Dr Eftekharul Alam pointed out.
The underground salinity is also changing the ecosystem and biodiversity of the country’s Southern part, which is about 17 per cent of the country’s area, reports BADC. “The agro-ecological characteristics and biodiversity of that area will become unsuitable for the present cropping pattern due to the presence of salt both in the surface and ground water. These will also reduce the crop production and compel people to migrate and become climate refugees,” the paper further said.
In Bangladesh, 80 per cent of irrigation water and 98 per cent of drinking water is collected from underground sources without proper study and planning. If the ground water level, the most valuable natural water resource of this country, is extracted continuously and polluted by saline water intrusion, experts fear that it will destabilise the food security, the ecosystem and biodiversity of the country’s coastal areas.
The solution and alternative sources
Experts believe that massive destructive situation is yet to occur in our country and there is still hope to overcome the problem. According to them, to prevent all these from happening, it is high time for everyone from all sects of society to work together.
“We need to reduce our abstraction of using ground water and limit it within the safe yield. We should start using more of surface water immediately,” Dr Eftekharul Alam said. WASA has not yet managed to reduce ground water extraction. Requesting anonymity, a WASA official said, “We have many barriers as the surrounding rivers of Dhaka are too polluted and it is difficult to recycle even through the treatment plants. We are also looking for alternative sources. It is true that without surface water, we have no options. We need more technical support, pollution-free rivers and sufficient budget to fulfil the ongoing projects.”
“We hope that we will be able to supply 70 per cent of the necessary water from surface-level sources within the next 10 years. We have some project to supply water from Padma, Meghna and Sayedabad Phase-3. Besides these, Sayedabad Phase-2 will be completed within December this year, which can produce 225million litres of water,” said Taksim Khan.
Experts also claimed that ground water has not been addressed properly in our draft Water Act. In the section 4.6 of our National Water Policy, expressing concern about water table depletion, it states, “Preserve natural depressions and water bodies in major urban areas for recharge of underground aquifers and rainwater management.”
“The Groundwater Management Ordinance 1985 was suspended in 1993. It allowed people to use deep and shallow tubewells as they pleased. Because of that, a large number of tubewells were installed without proper inspection and ignoring regulations,” informed Dr Eftekharul Alam.
Experts believe that an ordinance regarding ground water management may help control the misuse and irregularities regarding water usage. Regional cooperation is also essential to increase the water flow from the trans-boundary Rivers.
A water specialist, requesting anonymity, pointed out, “Farakka barrage causes serious obstacles in the water flow of the River Padma, which is one of the reasons for ground water depletion. Again, if the Tipaimukhi Dam gets constructed, it will severely damage the water flow of the River Meghna, which is our most important and vital river at present.
“Our state should take immediate steps to save our rivers for our own betterment and future generation by ensuring regional cooperation,” he added.
“We immediately need to decentralise the capital and reduce stress on the urban areas. It is also important to raise awareness about rain water harvesting, irrigation efficiency, water productivity and search for new sources of water,” several experts opined.
In addition, water pollution has to be prevented at all costs, and Effluent Treatment Plants (ETPs) set up at all the industries. “We also need to establish some artificial recharge system, like digging ponds in government lands,” said Anwar Zahid. This problem is like a time bomb; it will blow up at any time and cause a massive destruction, especially in our life, agriculture, industry, commercial sectors and economy, resulting in a long term effect, if preventive steps are not taken immediately.
This article was published at The Daily Sun titled “Extracting Trouble”