Floods are one of the most common natural disasters that are extremely deadly to living beings and property. It’s important that the shelters that protect beings from calamities be equipped with appropriate measures for dealing with such extremities. Depending on the rate of precipitation and the duration, floods are generally caused by heavy rainfall and thunderstorms. Dams and levees that break during stronger cases of rainfall with inadequate or improper measures taken to control overflow of rivers, wreak havoc in inhabited areas, causing serious repercussions in the aftermath.
In present times with the inevitable global warming which compromises the environment’s natural ability for restoration, extreme climatic changes have been leading up to an increase in the frequency of occurrence of disasters. In contour regions, water flows from ridges to valleys, thus increasing the potential for damage in floodplains where habitable structures are present. In flood-prone regions, it’s fundamental to build structures that can and will withstand floods.
The proper materials and construction techniques required to pull off proper protection to the property and especially the lives of living beings in and around the structures are of extreme importance. Countries have different methods of flood-resistant construction depending on the regional context, specific climatic conditions, materials available, etc.
Some intriguing and effective flood-resistant construction processes are prevalent in various countries, and they are including but are not limited to the following methods.
A series of floods that occurred in Queensland, Australia throughout the year 2011 led to the innovation of flood resilient construction techniques as opposed to structures that resist floods. The Brisbane-based firm of James Davidson has pioneered reality-based wet proof housing designs that allow the housing units to be restored with minimal damage. Pontoons designed by the firm are effective during floods.
The pontoon attached to a framework at the base of the house is connected to columns that support the walls and the pontoon rises with the rise in water level, thus raising the house in the process. The materials used are water-proofed with suitable substances. The design and planning of the house allow the water to percolate through the spaces which can then be drained post-flooding.
Indonesia, an archipelago in the Southern tip of Asia, is prone to floods more often than not and there is a specific method of flood-resistant construction that helps deal with floods. Many villages in Indonesia incorporate the concept of ‘building with nature’ where the structures are built in harmony with nature and not against it.
Construction of amphibious houses where conventional residences are retrofitted with a buoyant framework of foundation which is fixed to the ground using stable posts, but the buoyancy of the foundations potentially help make the house float over the surface of the water during floods. Amphibious houses work in harmony with the rise and fall of the water levels and do not levee the flood.
Lightweight materials like bamboo are used extensively in the construction of amphibious houses in Indonesia, which can be replaced after the events of flooding.
3. North-East India
The valleys of north-eastern India are susceptible to flooding, earthquakes, and cyclones. The houses are constructed on water-proofed bamboo stilts embedded into the ground using cement.
Similar to Indonesia, the housing units here are assembled using lightweight materials like bamboo, jute, and wood. The framework made of the said materials can be dismantled and reassembled quickly in case of floods and the houses can be raised higher in case of a rise in water level.
Bangladesh is one of the highest flood-prone countries in the world. Heavy rainfalls and the overflow of rivers are an annual calamity here. The flood-resistant construction prevalent here are houses built on concrete stilts that are 2 m high.
Bamboo skeletons and jute panels are used in the construction over reinforced concrete stilts in rural community areas where the materials can be replaced easily post-flooding.
The sea-facing side of Ghana incorporates flood-resistant construction similar to that of Bangladesh and north-east India in terms of materials and techniques. Houses assembled using branches from raffia palm trees are built over stilts moored to the ground.
The clustering of houses over the surface of water represents a symbiosis of people and Earth. The floating villages are not resistant to floods but are in harmony with the rise and fall of the water levels.
Amphibious houses are designed in parts of the UK in response to floods. Formosa is an example of a flood-resistant construction project near the floodplains of the river Thames. This amphibious housing unit is fixed on a base slab with retaining walls.
The primary material used in the construction is concrete with highly buoyant insulating materials which keep the house stable and also helps it stay afloat during floods. There are four vertical posts that navigate the house upwards during the event of a flood as the water level rises.
Based on the flood levels recorded and predicted, the house can rise to 2.5 m during flooding.
The seaward side of the Netherlands has been prone to flooding and since the devastating floods of 1953, novel methods of flood-resistant construction are being incorporated within the fabric of the cities. The technique of constructing houses on stilts prevalent in south-east Asia and South America was adopted in the Netherlands as well. Currently, floating houses and amphibious houses are being built extensively.
Floating houses have buoyant air-filled concrete foundations which help in floating atop the water during floods. Concrete flooring is used since conventional wooden floorboards are used in the Netherlands to avoid replacing waterlogged wood in the aftermath of flooding. Amphibious houses, on the other hand, are technically floating houses but they are anchored to the ground using piers.
The foundation is made using buoyant materials like expanded polystyrene and water-proofed autoclaved aerated concrete blocks which are lighter than water and help the houses stay afloat.
Similar to the Netherlands and the UK, the amphibious houses in flood-prone areas of the USA are built using buoyant materials like expanded polystyrene and water-proofed autoclaved aerated concrete blocks.
Floating dock houses built on piers embedded into lakeshores are also prevalent here.
In trying times such as now, it is necessary to embrace alternative methods of construction and restoration in the industry which causes a major portion of the repercussions leading to the climate crisis. Building sustainable structures, adaptive reuse, and transformation of existing spaces, etc., would be the only appropriate way to go about in the construction and planning of present and future cities.
With the rise in sea levels due to climate change, amphibious houses and floating houses may be the next step towards surviving on a planet on the brink of collapse.
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