Posted on Innovate Development.
The global average sea level has risen nearly 178mm over the past 100 years, with a current rate of change of 3.18mm a year.1 634 million people live less than 30 feet above sea level, and coastal cities and even entire islands – such as the Maldives and Kiribati – risk being swallowed by the oceans by the end of the century.2
In the wake of this accelerating change, a less combative approach to rising sea levels and floods is being considered. The normal approach has always been to build a wall, but increasingly, architects, developers and governments are questioning whether this is a sustainable answer to climate change.
From the countries where levees have collapsed and been overtopped – New Orleans after Hurricane Katrina, 2011 flooding in Thailand, the Japanese earthquake and tsunami – to the many countries in the process of constructing flood defenses to preserve their coastlines, this is an increasingly costly endeavour. According to a 2013 World Bank-OECD study, global flood losses are forecast to increase from $6 billion a year in 2005 to $52 billion a year in 2050, with just socio-economic factors taken into consideration. Including the risks of sea-level rise and sinking land, raises the potential total to $1 trillion a year, leaving many searching for ways to mitigate damages.3
For some countries, that involves a move towards non-defensive flood risk management, with an acceptance that it is better to work with water than against it. Increasing the resilience of infrastructure and communities is one of the first steps, such as with the development of amphibious and floating homes.
Floating houses are built on the water, and rise up with the raised water level in the case of a flood or storm surge. Suspension mechanisms ensure buoyancy and stability. Amphibious homes rest on the ground, but rise gently with floodwater. They sit in an excavated ‘wet-dock’, which allows water to enter and escape naturally and ensures that the house becomes buoyant before the major flooding begins. The house is secured with posts to prevent any side-to-side motion. The design of amphibious houses allows them to be much bigger and more stable than floating homes.4
In the U.K., the country’s first amphibious house was built on the bank of the Thames in 2014, a floodplain that is highly susceptible to flooding. Designed by Baca Architects, the house has a foundation of waterproofed concrete that extends around the lower ground floor. It is currently designed to rise two and a half metres, which can be extended.5
The Netherlands, over a quarter of which is below sea level, has spent hundreds of years constructing dams, pumps and drainage systems to keep out the North Sea. However, the country recognizes that this system has limits. In 2005, the Dura Vermeer group built 32 amphibious homes in Maasbommel that can accommodate a water level difference of up to 5.5 metres.6
Thailand, whose capital was historically known as the Venice of the East for its network of canals, is also beginning to take a more proactive approach towards flooding. In 2011, they faced the worst flooding in over half a century. Heavy rain, multiple tropical storms and powerful monsoons inundated over six million hectares of land, resulting in 680 deaths and 1.43 trillion baht (USD 46.5 billion) in damage and losses. They’re the 7th most flood prone country in the world, and expected to be 4th for climate-change related economic losses by 2030.7
In response, Thailand’s National Housing Authority (NHA) reshaped their goals and began experimenting with ways to cope with more extreme weather. In 2013, the firm Site-Specific Co. Ltddesigned an amphibious home in Thailand’s Ayutthaya province. Built over steel pontoons filled with Styrofoam, the house can lift 2.8 metres off the ground. At the moment, the construction process system is labour-intensive and requires specifically trained construction workers, but it is a step towards understanding which materials and processes work best.
For Chuta Sinthuphan, an architect for Site-Specific Co. Ltd, “We can try to build walls to keep the water out, but that might not be a sustainable permanent solution. It’s better not to fight nature, but to work with nature, and amphibious architecture is one answer.”8
Amphibious houses currently cost about 20 percent more than conventional buildings, the result of having two foundation systems.9 As such, they are still inaccessible to the vast majority of the world’s population. However, for those living in high flood risk regions, the initial investment is far less expensive than the potential aftermath.
- http://climate.nasa.gov/ ↩
- http://www.npr.org/templates/story/story.php?storyId=9162438 ↩
- http://www.worldbank.org/en/news/feature/2013/08/19/coastal-cities-at-highest-risk-floods ↩
- http://amphibioushomes.weebly.com/what-exactly-is-an-amphibious-house.html ↩
- http://www.dezeen.com/2014/10/15/baca-architects-amphibious-house-floating-floodwater/ ↩
- http://www.wired.co.uk/news/archive/2012-02/15/the-uks-first-amphibious-house ↩
- http://www.gfdrr.org/sites/gfdrr/files/publication/Thai_Flood_2011_2.pdf ↩
- http://www.trust.org/item/20150305000156-r6las/?source=leadCarousel ↩
- http://www.bbc.com/news/world-europe-26302176 ↩