The storm ‘Amphan’ had devastated the Sunderbans in May 2020 causing enormous damage to lives and livelihoods of the hapless people settled there. As per estimates of the State government, as reported in media, 28 lakh houses, 17 lakh hectares of agriculture land, 21 lakh domesticated animals and 8,000 board were affected. The storm led to problems with supply of drinking water, damaged roads, forests, power supply lines, education and health infrastructure and activities of some 26,000 MSM entrepreneurs. The genesis of destruction was mainly floods caused through breaches in 245 km of earthen river bunds and 36 km of sea bunds.
When storm ‘Aila’ struck the Sunderbans in 2009 and the government approached the Water Resources Section of the Civil Engineering Department of IIT, Kharagpur for suggestions to resolve the problem permanently, it was recommended to replace all earthen river bunds by breach-resistant, concrete-reinforced earthen embankments. On further request, the faculty, in collaboration with a field experienced alumnus, evolved the innovative ‘Reinforced Earthen Embankment’ technology using precast reinforced concrete material.
It is anchor-shaped, stands on three legs and has three arms protruding upwards. It weighs around 40 kg and was developed under the alumnus, during his tenure in Kolkata Port as River Training Engineer, while executing river projects like stabilisation of ship channels, arresting bank erosions etc.
The material, then named a Hexapod, was brought to public notice through a number of papers published in technical journals, the first one entitled “Use of Unconventional Materials in the construction of Nurpur Spur, River Hooghly,” in Irrigation and Power Journal, Vol. 36 No.2 April 1979 issue and the last one titled “Reinforced Concrete Hexapod an innovative Material for River & Shore Management” in Institution of Engineers (India) Journal , Vol.87, May 2006 issue that was awarded a prize.
The Hexapods had been extensively tested in the port’s river corrective works and found very effective. As such, they are proven materials. The Oceanology Department of IIT tested it again in the laboratory to verify authenticity of claims regarding its efficacy as stated in the Journals. It was renamed ‘Spider’ because of its ability to be interconnected to form endless chains without any other aid. These chains are placed horizontally and vertically, with vacant spaces being filled with sand to form an impregnable concrete based wall inside the earthen embankments, and this makes them breach resistant. Additionally, 6G galvanised iron wires can be put through the holes in their legs to make these cluster of Spiders more resistant.
IIT’s Water Resources Wing intimated the government about the innovative Reinforced Earthen Embankment technology with a request to test it in pilot projects at bund sites affected by Storm ‘Aila’. Unfortunately, after initial enthusiasm, the government response was lukewarm.
We need to understand that only a breach-resistant, concrete-based wall inside the earthen embankment can protect Sunderbans from the fury of storms like ‘Aila’ and ‘Amphan’. Moreover, the benefits from construction of breach-resistant embankments are manifold. These are: freedom from annual ritual of floods to enable islanders to plan their livelihood; saving of flood relief expenditure; retention of entire catchment rain to resolve drinking and agriculture water problems; less migration of rural labour to urban centres of different states in search of employment, and finally, freedom of villagers from insecure feelings and sleepless nights during the monsoon.
It may be mentioned that if Reinforced Earthen Embankments are used all over the country there would be further benefits, apart from those listed above. These are: entire catchment rain water harvesting without loss; pollution-free rivers including the Ganga; arrest of land silt going into the rivers with rainwater run-off and thereby protecting river drafts with least maintenance dredging, for benefit of Inland Water Transport system, and saving of rivers from being dried up due to annual land silt deposit through breaches in the bunds in monsoon by rain water run off.
Incidentally, the rural populace can be employed under the Mahatma Gandhi rural employment scheme to construct and maintain their own protection bunds. This will make the technology cost effective. It will be a misfortune if despite availability of low-cost, rural employment-oriented indigenous technology, the 245 km of river bunds and 36 km of sea bunds, reportedly damaged by ‘Amphan’ are not repaired properly to make them breach resistant and to save the Sunderbans. Nature gave a warning call in 2009 through ‘Aila’ and a wake-up call in 2020 through ‘Amphan’.
The writer is an IIT alumnus and a former River Training Engineer at Kolkata Port.