Fillip to stop river erosion - Geo-synthetic technology used to build embankment

Construction of the embankment with geo-synthetic technology in progress on the bank of the Sishamara river. Picture by Biplab Basak

TT, Jalpaiguri, May 8: For the first time in Bengal, the state irrigation department is using geo-synthetic technology to build an embankment on the bank of a river in Alipurduar district.

The decision has been taken to protect the Jaldapara Wildlife Sanctuary and also the villages located under Salkumar I & II panchayats, which are next to the reserve forest, from erosion and inundation, caused by the Sishamara river that flows through the area.

"We are using geo-synthetic tubes and aprons (sheets) to build the embankment. This is the first time that our department is building an embankment with this technology, instead of using common materials like boulders, wire-nets, cement and sand. If we succeed in this project, similar technology would be used in building embankments along other rivers in the state," Rajib Banerjee, the state irrigation minister, said over phone from Calcutta today.

Work has already commenced on the site and will finish in another two weeks, officials of the department said.

On the site, vertical tubes which are around 30ft long and made of geo-synthetic material have been lined up, with iron stands put inside for stability. These tubes, made of polymer, will be filled with earth and then, aprons or sheets of the same material would be used to cover the opening of the tubes.

"Length of the total dyke will be around 1.5km. We are spending Rs 4 crore on the project. Such a reinforced wall of geo-synthetics lasts for around 10 years and during the first five years, there is no maintenance cost," Subhankar Chakraborty, the superintendent engineer of circle-I under northeast division of the department, said.

Sources in the department said water from the Torsha river, which flows close to Sishamara, had breached its bank in 2015 and 2016 and had flooded Jaldapara and the adjoining villages.

Such repeated inundations, which posed a problem for the 30,000-odd population living in the two panchayats as well as the wildlife, made Sourav Chakraborty, the Alipurduar MLA, speak with the state irrigation minister.

The project was taken up and finally, work began around one-and-a-half months back. "Another reason for adopting the technology is to ensure that minimum disturbance is caused to the wildlife of Jaldapara. If we had done it in the traditional manner, trucks carrying construction materials would have entered the forest area several times. Also, we could finish the work within two months whereas, if the embankment was done with concrete, it would have taken more than three months. The costs would have also escalated," the superintendent engineer said.