Two Kerala-based researchers, M.V. Varkey and Philbin M. Philip, have designed a mechanism to prevent houses from being submerged in floodwaters. The researchers belong to the A.P.J. Abdul Kalam Technological University in Thiruvananthapuram who have published their work, titled ‘Flood risk mitigation through self-floating amphibious houses—Modelling, analysis, and design’, in the Materials Today, a monthly peer-reviewed scientific journal.
The state of Kerala has experienced the most devastating floods in its history, which impacted about 20 per cent of the state’s population. This situation forced researchers to look for more effective flood mitigation strategies in the flood-prone districts of Kerala. Therefore, the researchers came up with an interesting proposition of houses that float during floods. Called as ‘amphibious architecture’, the mechanism enables a standard structure to float in floodwater rather than getting submerged. This structure rests on Earth but is designed to rise during flood through a floatation mechanism underneath the house. It would stay afloat at one spot, supported by the floodwater. The researchers have examined the floating architectural technology by researching floating structures, materials, working models, and foundation design.
Amphibious housing is not a new technology, and is widely used in Canada, Britain, the Netherlands, Bangladesh, and Philippines. An amphibious house has a buoyant foundation and guidance posts that would allow up and down movement for the orderly rise and descent of the house, and to resist horizontal movement. It has a wet dock and debris control to restrict the flow of debris to the bottom of the floating house, during a flood. Flexible utility connections for water, waste water, and electrical lines are some of the special features of amphibious house. Special utility connections could be connected to the main supply so that utilities would remain intact when the flood water comes in and the house rises or start floating.
What the Architecture is Made of
The house has been designed using waterproof materials and sustainable architecture. The floating deck is constructed using fiberglass cylinders. Fiberglass is one of the materials widely used in the construction of boats. The perpendicular guide poles were connected to the long flat bottom, boat-like structure, which provided resistance to the lateral wind and water pressures. According to the Archimedes Principle, the buoyant force upon submerged object equals the weight of the fluid displaced by it. So, the hybrid home has been constructed in such a way that its load is equal to or less than the uplift force of water, allowing it to float.
The materials used in the construction include expanded polystyrene (EPS) blocks, glass fibre reinforced concrete (GFRC) coating, glass fibre reinforced gypsum (GFRG) panels, concrete barges, ferro cement, fibreglass, and bamboo. The experimental structure measured three metres tall and was made of 12.4cm thick GFRG panels on a base of fibreglass hollow cylinders to keep the building afloat. Fibreglass was used as it has a low corrosive rate and does not affect the water. The GFRG panels and fibreglass cylinder arrangement would help lower the centre of gravity of the house, and also improve its stability. The roof has been made of lightweight steel.
Pros of the Technology
According to the researchers, the foundation could be a driven pile, with a floating section made of fibreglass cylinders. If loading exceeds the limit, then a pile foundation could be installed under the four guide poles attached to the base truss. If the weight of the proposed construction appears to be more, then soil stabilising process could be used. (Soil stabilisation refers to any physical, chemical, mechanical, biological, or combined method of changing a natural soil to meet an engineering purpose).
Cons of the Technology
This design and technology have its own limitations. The structure could disintegrate in saline water, while flowing water would gather mud and muck. Over the time, the mud could cause the utility connection to deteriorate and further, the steel could also corrode. The researchers are optimistic that solutions to these problems could also be found over time.
Well before the research of M.V. Varkey and Philbin M. Philip, a translational engineer and entrepreneur, Nanma Gireesh, of Kollam district in Kerala, had started working on amphibious housing projects. (Translational technology is the implementation of researchers to offer a sustainable solution to critical natural problems such as flood, lake rejuvenation, etc. It is not just classroom knowledge but is project-based and practical-oriented.)
NestAbide is a start-up which has built a working prototype of amphibious building technology, with a concrete buoyant foundation, built to set an example of a flood resilient construction technique so that people could continue their usual living style without compromising much during floods.
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