Problem:
Since 1880 – 140 years ago – global mean sea level has risen about 8–9 inches (21–24 centimeters), with about a third of the rise coming in a sixth of that time – the last 25 years.
From 2018 – 2019 alone, sea level rose 0.24 inches (6.1 millimeters) to a height of 3.4 inches (87.61 mm centimeters) above the 1993 average. Data from a U.S. Geological Survey estimates sea levels could rise another 19 in. (48 cm) in the next 30 years.
Solution:
Amphibious houses that combine the best features of floating house boats with the best features of elevated buildings.
House boats have been with us for centuries and are designed to adapt to changes in water level, but cannot safely withstand storms with high winds or floods with fast moving water.
Elevated homes are safe from flooding and wind if constructed properly, but can feel isolated from their neighbours and the surrounding environment due to their high decks and extensive stairs.
Netherlands
The Netherlands is a country with a long history of mitigating flood damage and adapting to flood risk, with 60% of the country below sea level.
The development and implementation of flood resilient infrastructure has become an important part of the Dutch culture.
The flood threat in the Netherlands is not only related to rising sea-levels, rivers also pose a risk of flooding. This risk is increased by climate change as it causes more frequent and extreme rainfall.
An answer to this can be found on the Maas river, in Maasbommel, where the country’s first amphibious houses were realized in 2005.
Designed by a team led by Adrianus Gerardus Gregorius van Haastert, Richard Jacob Looij and Josephus Antonius Wilhelmus Hockx and built by the construction firm Dura Vermeer Beton & Waterbouw BV, the development encompasses 14 floating houses / house boats plus 32 real amphibious houses plus.
The amphibious houses in Massbommel float like house boats sited on a floating concrete “hull.” However, they are also secured against strong winds and waves by permanent mooring posts driven deep into the ground, similar to those used to elevate homes.
In every day non-flood conditions, the houses rest on the river bank, allowing for convenient water access and creating a flat walkable space between homes. When waters rise, the posts guide the building to rise and lower, in place, according to changing river levels.
Unlike a house boat, the amphibious houses also have basements, decks, and small gardens all supported by their foundations. They feature flexible pipes for electrical, water, and sewer lines that will keep the home “on the grid” even in a flooding event.
Dura Vermeer have also built floating houses near the Limburg village of Ohé en Laak. These homes, known as the Meuse Villas, consist of a concrete floating barge, including the shell, and each home weighs approximately 100 tons.
Although the technology of amphibious houses proved itself during a flood in 2011, the concept has only been moderately adopted in the Netherlands.
The obstacle has been obtaining building permission, due to regulators being unfamiliar with the concept and hesitance to approve building in areas that were considered dangerous. Another important difficulty is that an unconventional building approach leads to higher construction costs, combined with a limited market of possible owners.
Germany
Bungalow Boote (Bunbo) are very popular on the vast northern German waterway network, also on the Lahn river. Hulls are aluminum, superstructure made from wood. Typically used for charter (short-term, weekly), they are also good for older people and those with disabilities. Propulsion is electric, power is solar (100 watt) and cooking/heating by gas.
Czech Republic
In the Czech Republic, architect Marek Štěpán of Tachov in the Plzeň Region, has designed and built a series of prefabricated one-bedroom floating homes called Freedomky, which can be towed to a selected venue, such as Charles Bridge in the up-and-coming district of Smíchov in Prague.
Elizabeth C English, Carol J. Friedland, Fatemeh Orooji, “Combined Flood and Wind Mitigation for Hurricane Damage Prevention: Case for Amphibious Construction,” Journal of Structural Engineering, February 2017.
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