This article presents notable modern examples of construction to prevent flooding.
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Early civilizations grew around river valleys, and today the majority of cities in the world are close to water. Buildings in these cities often have to deal with the effects of these water masses breaking their banks and flooding the streets, and building traditions around the world have developed methods to avoid flooding. This article examines some of these methods.
Flood Resistance vs Flood Resilience
Flood-resistant buildings are designed to keep flood waters out. They tend to be constructed of concrete or a mix of concrete and steel, although watertightness can also be achieved with masonry and an impermeable membrane such as water-resistant plaster, plastic sheeting, or asphalt. It is generally more difficult to make frame buildings flood resistant without using a layer of concrete or masonry. This is due to the higher number of entry points around frame junctions.
Buildings designed to keep water out must also use specially designed doors, windows and utility connections to avoid weak points in the impermeable layer.
Flooding occurs above and below ground as the water table rises and pushes residual moisture up through the cover soil. This means that flood-resistant buildings must also waterproof their floors.
With higher levels of flood water around the building, it is becoming increasingly difficult to keep the water out. Water moving at a higher speed, for example river water at full flood, also increases the pressure on a building’s flood defenses.
In addition to potential leakage through the water resistant layer, flood resistant buildings must also be protected from increased and unusual mechanical forces exerted on their structures. Water rising outside the building creates forces on the exterior walls and ground floor, and rising water under the house can push the ground down. Flood resistant buildings may require reinforced concrete floors or additional waterproofing under beam and block floors. The membrane may also need to be weighted down to prevent water from forcing the soil up.
A third factor that causes floodwaters to cause more damage (after a rise in water level and an increase in velocity) is the time it takes for the floodwaters to recede. Areas with flat topography, such as lower river valleys and many coastal regions, can experience residual flooding for days or even weeks.
Considering all these factors, most building traditions that have faced flooding have tended towards flood resilience rather than flood resistance. Flood-resistant construction prevents flood waters from reaching the building in the first place. This includes the design of buildings where the lower level can be submerged without causing major damage, for example by placing service points and electrical infrastructure higher on the wall or above ground level.
Other examples of flood resistant buildings include floating buildings, buildings on stilts, buildings with dams and flood walls around them, and buildings simply constructed further above flood levels. usual for the nearby body of water.
Building to prevent flooding around the world
The LIFT house (Dhaka, Bangladesh)
The LIFT house (Low Income Flood-proof Technology) was designed and built by Prithula Prosun for her Masters Thesis. His work has focused on creating innovative flood-resistant housing for low-income neighborhoods in Bangladesh’s capital. The LIFT House is economically made with a bamboo frame and recycled plastic water bottles. During floods, it can float above a hollow ferrocement foundation before returning safely to dry ground after the flood waters recede.
The Float House (New Orleans, USA)
The New Orleans Float House was also designed to help those in need. After the devastation caused by Hurricane Katrina in 2005, Morphosis Architects designed a low-income housing project that could be mass-produced quickly and economically. The floating house is prefabricated, self-supporting and can survive flooding by rising on signposts above a floating foundation. The architects have ensured that the vibrant vernacular of Big Easy architecture is maintained with their colorful and historically informed design.
Flowering bamboo house (Vietnam)
The Blooming Bamboo Home by Vietnamese architecture studio H&P Architects is another affordable solution for flood-resistant housing. The bamboo structure is raised on stilts up to three meters from the ground and accessible by wooden ladders to a terrace that surrounds the entire house. The exterior of the building is made of bamboo, fiberboard and coconut leaves. The versatility and local availability of these materials makes the design fully customizable without specialist intervention.
Anti-flood house (California, USA)
A beach house in the Golden State can withstand up to four meters of storm surge or rising seas. Studio Peek Ancona’s design is also pre-engineered and includes a metal unit set on two concrete and steel columns fixed to the ground with a steel-reinforced concrete foundation. During floods, the ground floor garage detaches from the foundation and floats under the rest of the building perched on the columns. The staircase is placed at right angles to the sea, so that rising water or waves pass through rather than against the steps.
References and further reading
Barker, R. (2021). Flood resistant construction. Designingbuildings.co.uk. [Online] Available at: https://www.designingbuildings.co.uk/wiki/Flood_Resistant_Construction.
Gattupalli, A. 10 examples of flood-resistant architecture around the world. Repenserlefuture.com. [Online] Available at: https://www.re-thinkingthefuture.com/designing-for-typologies/a2295-10-examples-of-flood-resistant-architecture-around-the-world/.