BANK LINING KILLS CANALS
Though it is essential to recover the city canals from encroachers and increase its width to save Dhaka from flood and waterlogging, Dhaka Water Supply and Sewerage Authority (Wasa) has turned around13 canals to concrete drains which significantly reduced the canals' water carrying capacity.
Experts said Wasa in the name of protecting and demarcating those canals through U-channels and trapezoidal CC block lining (an impermeable layer provided at the sides of canal to improve its life and discharge capacity) virtually reduced their widths.
During construction of those U-channels and lining work, in most of the cases, Wasa did not follow the CS maps to protect the canals properly, and the work also created scopes for grabbers to encroach the canals.
Though the lining and U-channels protected the canals from encroachers but it reduced the canals' width in many cases; the work should have been done keeping it wider, said experts.
Wasa took the initiative of constructing RCC U-channel and trapezoidal CC block lining on 13 canals under “Dhaka Water Supply and Sanitation Project”, funded by World Bank, which started in 2009 and continued till 2016.
The canals where RCC U-channels were constructed are Khilgaon-Basabo khal (canal), Khilgaon-Basabo up stream, and Gerani, Sahjadpur, Mohakhali and Segunbagicha khals.
Block lining work was done in Sahjahanpur, Kalynapur main khal, Abdullahpur branch khal, Abdullahpur and Segunbagicha khals.
Apart from those, earth cutting and demarcation work were done in Digun and Sutivola khals under the project.
More canals also partially came under Wasa's CC-block lining work, including Katasur, Ramchandrapur, Kalyanpur Ga, and Ka and Ibrahimpur khals out of the project.
During a recent visit it was found that most of these canals were not demarcated following the actual width of the canals which were much wider even in the 70s or 80s.
“The Gerani canal was huge even in the 90s as big size boats used to run through it. The canal had a link with Trimohini,” said Md Jobbar, a Manda resident. “I went to Trimohini through Gerani in the 90s on a launch during the rainy season,” he said.
Even in the dry season its width was around 40 feet and rest of the land would dry up and turn to a paddy field, he said.
Segunbagicha and Khilgaon-Basabo canals were also huge and had a link with the Gerani canal, he said.
But Gerani was turned to an 8.2 metre U-channel, Khilgaon-Basabo to a 9.5 metre U-channel and Segunbagicha canal was turned to a 19 metre U-channel with CC block lining.
All the three canals now confluence at Manda and fall into the Balu river through Manda khal which also became very narrow, said locals.
But according to a CS map record, width of the Gerani canal, which was under Dakkhingaon Mouja, was 25 to 120 feet, which started from Trimohoni and ended at Manda, where its width was 40 to 45 feet.
But it was seen that Wasa has constructed U-channels keeping around 25 feet (8.2 metre) width.
Even according to the list of canals at the Deputy Commissioner's (DC) office in Dhaka, the Gerani canal is mentioned as Dakkhingaon-Nandipara canal and its width is 60 to 130 feet.
The other canals will be more or less the same since Wasa did not try to maintain their actual widths as per the CS map during the construction of the U-channels.
Managing Director of Wasa Taqsem A Khan, however, said Wasa followed the CS map during construction of the U-channels and lining work.
“If a canal comes under the lining work it remains protected from encroachment most of the cases,” he said, adding that after the work encroachment becomes easily visible.
“Without the lining work, it is easier for encroachers to fill one or two feet of a canal and afterwards confusion arises as to whom the land actually belongs.” So the decision taken at that time was a right one, he said.
Taqsem said lining and setting up walkway is very necessary after the bank protection work since a walkway also does the work of demarcation.
Prof Mujibur Rahman of Bangladesh University and Engineering Technology (Buet) said the capacities of the canals are seriously reduced due to the U-channels.
“When it is imperative to increase the canals' capacity to manage storm water, Wasa reduced the capacity of the canals. Through the work they have turned the canals into drains,” he said.
Wasa through the U-channels has reduced the storm water carrying capacity of the canals drastically, he said. “When experts are criticising the concept of box culvert, how could Wasa go for this kind of concrete drain again?”
Regarding Wasa's claim of doing the work for the canals' demarcation, Prof Mujibur said it is wrong to assume that encroachment will not be done this way.
“We suggest increasing a canal's width to 100 feet when it remains 60 feet; 70 feet if it is 40, but during the U-channel work they turned around 80 feet wide canal to 20 feet.”
Prof Mujibur suggested stopping construction of U-channels replacing canals and reassessing its conveyance capacity considering present and future runoff.
Architect Salma A Shafi, joint secretary of Bangladesh Poribesh Andolon (Bapa), said a canal should be kept natural.
Salma, who carried out a survey on the city canals around five years back, said revival and proper management of a canal has to be planned. “A canal is a natural entity and it is a tributary of river. But Wasa has turned them to drains.”
“When a canal turns to drain, people will dump waste; they will connect sewerage line and it will remain no longer a canal,” she said.
To protect the canals, walkways or footpaths will have to be constructed beside the banks. “Not only are we wasting money by constructing concrete drains but also damaging the canals,” she added.
Iqbal Habib, another joint secretary of Bapa, said total area of a canal should be determined calculating the entire runoff of a region. “Now Wasa is trying to restore the canals according to its current state,” he said, adding that the actual area (paridhi) and canal space are being squeezed for that.
The canals are being narrowed down more in the name of constructing channel and lining work, and eventually it becomes a garbage drain as it turns to a dead canal. “It is a wrong process,” he said. Iqbal suggested protecting the canals by restoring it and its banks using different methods calculating the region-based runoff water. He also suggested creating a connectivity between the canals, bills (water bodies), and jheels since all of those complement each other.
If it is possible to restoring the canals properly and ensuring its connectivity, only then the canals' effectiveness will remain active, otherwise the canals turn to a dumping zone, he stressed. He suggested constructing walkways recovering the canals properly and stopping dumping of garbage into the canals. “If necessary the government should forcibly recover the canals based on the original map (CS map),” he said.
Though many claimed that the canal lands belonged to them and showed papers as proof but those were forged. If needed, the government should offer compensation to recover the canals, he suggested. To save the capital from waterlogging, the government will have to bring back the natural drainage system. “We are observing that the intensity of rain is increasing due to climate change. It will be a normal phenomenon in the near future when 300 to 400 millimetres of rain will fall within a day,” he said.
"The capital will face a huge waterlogging crisis at that time if we do not act now and protect the canals," Iqbal added.
Comments