The irrigation department has taken up the work of desilting the canals. A sum of Rs 35 crore had been sanctioned by chief minister Mamata Banerjee right before the Bidhannagar municipal elections for this .
Dredging is on at both Bagjola canal and Kestopur canal network. Debraj Chakraborty, mayor in council in charge of drainage and solid waste management, Bidhannagar Municipal Corporation, said: “In the lower Bagjola canal stretch, flowing from VIP Road to Kulti, work is on at full tilt. In upper Bagjola, which is till VIP Road, work has just begun. Work at Kestopur canal is also on. All other canals in the Rajarhat Gopalpur area will be excavated in due course.”
Work started about two weeks ago and is expected to continue for a year.
Such extensive dredging is taking place after more than five years. “An estimated deposition of 10 inches to one foot of silt takes place per year. So we plan the dredging at an interval of about five years by when the deposition is substantial,” an irrigation department official said. Only upper Bagjola Canal, he said, had been desilted three years ago. “But given how its adjoining areas like Kamarhati, Panihati and south Dum Dum suffered water-logging last monsoon, we have decided to dredge that stretch again.”
The Bagjola canal flows for a length of over 38km, with the upper part being 28.8km long. The Kestopur canal, which starts from the Hooghly at the Chitpore lockgate with the name Circular Canal and takes the name Bhangarkata Canal to fall into the Bidyadhari, is almost the same length.
The urban development and municipal affairs is also dredging the Eastern Drainage Channel (EDC), which flows by the east of New Town and alongside Salt Lake Bypass. A proposal to dredge upper level of the EDC, called Beleghata Circular Canal, will be sent to the finance department for approval.
Pumphouse power needed
However, just the desiltation will not be enough to completely rid east Calcutta of inundation woes. The irrigation department has done a mathematical model study by feeding hydraulic data into a simulation software, with assistance from the hydrology department of IIT Kharagpur as also Dutch experts, with whom a tie-up has been forged at the Bengal Global Business Summit. “It was seen that the Kulti pumphouse at the tail end of Bagjola Canal is inadequate compared to the drainage discharge. We have prepared a proposal for capacity augmentation which will be sent to the finance department. When water from Bagjola cannot get discharged during tidal activity in the Bidyadhari, the pumphouse is pressed into operation. Currently due to siltation, the canal discharge capacity is down to 50 to 60 per cent. Once we complete the dredging, the canal’s drainage will be back to full capacity. We have found that close to 5,000 cusec water accumulates at the tail end of the canal while the drainage capacity of the pumphouse is 1,650 cusec. So water stagnates in the canal for days even 40km upstream, which is what had happened last monsoon. If the pumphouse capacity gets augmented to 4,000 cusec, the water that now takes one or two days to clear will then be drained in three hours,” an official explained.
North 24-Parganas district magistrate Sumit Gupta inspected work on Monday. “Dredging will continue through monsoon. We are using pontoon-mounted excavators, which can float,” said a district official.
The canals along VIP Road in Bangur Avenue, Lake Town and Dum Dum Park are in bad shape, being full of litter. The stretch is also facing the threat of illegal landfill as also encroachment on the sides. “Due to lack of awareness about their importance, the canals are getting reduced to longitudinal garbage vats,” lamented a civic official.
Asked about the desilting of canals in the South Dum Dum Municipality area, chairperson Kasturi Choudhury said: “I have already sent notices to the respective departments. Desilting of canals along VIP Road will begin soon.”