Dambarudhar Hazarika of Narayanpur (in North Lakhimpur district of Assam) discovered this whole bioengineering approach of controlling river erosion with the help of plastic nets and vegetation in the year 2005. He has grown up along the banks of the River Dikrong since his childhood and has seen how the river has frequently changed course over the years. And he has also witnessed devastating floods – the raging torrent that destroys human lives and ruin crops – which is further exacerbated by river bank erosion which destroys huge swathes of riparian land along the river.
As Dambarudhar grew up, he became a kind-of “guardian” of the river and knew the kind of relationship the farming community shared with the said river. “A recurring thought that invaded my mind when I grew up was – how to control erosion through low-cost indigenous technology. The various methods used to control erosion – bamboo fencing and porcupine fencing, groynes or spur, boulder pitching, river dykes, etc., has so far not yielded the desired results and is not suitable for the soil structure of Northeast. Keeping all this in mind, I discovered this whole bioengineering approach of controlling river erosion with the help of plastic nets and vegetation around 2005. I knew that the lethargic administration would hardly help me out and decided to control erosion through community initiative.”
Bent on finding an “eco-friendly solution” to the repeated problem of erosion which was causing much ravage in and around Bihpuria revenue circle, the septuagenarian opened a NGO in the year 2006 – Polygon Foundation (North East). The NGO started a pilot project – ‘Controlling River Erosion by Plastic Net and Bio-System’ – in the year 2007.
Dambarudhar informs, “The said project was taken up to arrest erosion in affected reaches of Morichapathar and Boraikhana located on the right bank of River Dikrong – a north bank tributary of Brahmaputra. These two places were ravaged by flood and the Rasaraj Bezbaruah High School, standing on the bank of Dikrong, was all set to get eroded.”
Explaining the bioengineering method (in the generic sense), he said that the river bank is “cut and slanted at 300 angles to facilitate the placing of plastic nets in layers along the erosion affected bank. Four layers of nets are placed so that it can limit the speed of the water current during floods. The nets are made by the local people from plastic ropes. As per the depth of the river, the plastic nets are extended from 10 m to 25 m width and the nets are placed in such a manner that they result in one net. One end of the net in the river water is kept firm by placing RCC blocks with GI wire and RCC pillars wherever necessary.”
Talking about the vegetation part, Dambarudhar further stated that aquatic plants (in the generic sense) like Bamkolmou (Ipomoea gigantica) and Sthalapadma (Hibiscus mutabilis) are planted prior to the placing of the nets. The nets are then placed over these plants. “The Bamkolmou branches are placed within the nets and they grow through them and spread out towards the bank. This reduces the strong velocity of the river and arrest suspended particles. Since the Sthalapadma trees are bigger, its branches are inserted at different intervals inside the nets. In due course, they grow into bigger trees and their roots prevent the river bank soil from erosion,” he further puts in.
The pilot project was sponsored by NEDFi and IIT-Guwahati was the technical consultant of this project.
Dr Arup Kumar Sarma of IIT-Guwahati, who “immensely” helped Dambarudhar in implementing the project, observed, “The said process of protecting the river bank has immense scope of implementation in small- to medium-size rivers provided the design is made according to the size and strength of the river.”
Dr Mineswar Hazarika, who is a faculty at the College of Veterinary Science, AAU, Guwahati, and also the younger brother of Dambarudhar, has also been a part of the project. Talking about the benefits of the said technology, he pointed out, “If it is applied in a big way, it will not only help in controlling erosion, but will also help in reclamation of wasteland. Since it is an eco-friendly technology, it helps in afforestation. The branches of the Sthalapadma trees can be used as fuel and its leaves are a good fodder for animals. The technology will also help in channelisation of rivers in Assam and last but not the least, since the nets are made from plastic ropes, it will serve a dual purpose – controlling the damage which plastic is causing to the environment and setting up of ancillary industries which, in turn, will create employment avenues for the youths.”
“As the former Congress Government in Assam did not show any interest to replicate the said technology in other erosion-affected areas, we wrote to the PMO office in 2015 and got immediate response. The PMO directed the Brahmaputra Board (which is now under the Ministry of Water Resources, River Development and Ganga Rejuvenation) officials to visit the Dikrong River site. Engineers visited the site and came back satisfied. The Brahmaputra Board then constituted a high-powered committee to study the fact whether the said aquatic plants helps in controlling erosion and were convinced that this bio-system of protecting the river bank with the help of the local people is a very positive approach,” adds Mineswar.
Dambarudhar puts in, “The Brahmaputra Board expert committee is studying our project so that we can replicate the same in some other tributaries of the river and AAU, Jorhat, also wants to assign an erosion control project to us. The Gauhati University is also getting in touch with us.”
Dambarudhar concluded by saying that he just hopes that the present Sonowal Government gives importance to this novel erosion control technology and “we hope to replicate the same in lower part of Majuli and with Government help, erosion can be controlled in all tributaries of Brahmaputra in northern part of Assam.”