Britain has faced its worst flooding in years, just a few weeks ago the Victorian city of Geelong experienced dramatic flash flooding and the Queensland floods of 2011 are still fresh in the minds of many.
For architects, developers, builders and engineers, thoughtful and strategic ways to deal with flash flooding and inundation from rain events is a necessity – especially when considering projects to be built near rivers or flood plains where flood risk management becomes vital.
In Australia, floods cause more damage on an average annual basis than any other natural disaster. Historically our towns developed on riverbanks to facilitate the shipping of goods to and from the settlements but this also left them vulnerable to inundation.
Understanding flood behaviour is essential for understanding and managing flood risk, and includes comprehending the:
- range of potential flooding and the implications of a changing climate
- flood function of the area, particularly conveyance and storage of water
- variation in flood hazard within the floodplain – this depends upon flow depth and velocity, and the interaction of the flood with the landscape, which can isolate areas from flood-free land and result in difficult evacuation situations.
Emergency Management Australia has put out an updated handbook – Managing the floodplain: a guide to best practice in flood risk management in Australia. One of its recommendations is the formation of a comprehensive information hub that looks at the likelihood and impact of flooding and encourage developers to identify potential risks and outline solutions.
The State Emergency Service of New South Wales has a handy booklet called – Reducing Vulnerability Of Buildings To Flood Damage – Guidance On Building In Flood Prone Areas and examines the pros and cons of various construction methods.
Builders and architects in the UK are using imaginative approaches to dealing with flood risk.
Engineer Carl Canty (pictured in featured image. Source: Daily Mail) fell back on his engineering degree for a solution to prevent his home on the Derwent River from flooding:
The 55-year-old precision engineer designed and helped to fit flood walls, gates and pumps that have saved the house from devastation.
Two hefty gates and a flood wall between the house and the garden act as the main line of defence.
Inevitably, some water seeps underneath, so a sump was dug nearby and fitted with automatic pumps to feed the water back into the river.
The walls of the three-bedroom cottage near Selby, North Yorkshire, are lined with a waterproof membrane which acts like a layer of cling film to hold water back.
For Baca Architects, the solution has been to create an ‘amphibious house’:
‘The river and ground water are hydrologically linked. During a flood, as the River Thames rises so will the ground water on the island. The dock fills gradually from the ground, gently raising the building, as the river level rises,” the architects said on their website.
When the water is just below the ground level the house becomes buoyant. It can rise up to 2.7 metres to cope with a 1 in 100 flood event. In the event of an even larger flood, there are guide posts that extend almost four metres above the ground, so even if flood waters continue to rise the house would still be retained between the posts.
In the time since the 2011 floods, we have seen developers address specific issues in new Brisbane buildings. For example, a building which has a fully sealed basement raised from the ground level by 2 metres. The driveway is also raised. Also developers are installing separate lifts to go from basement to ground floor and separate lifts that go from ground level to the top of the building, so even if the basement flooded, the apartment lifts will work independently, with all of the mechanicals housed above the ground floor level.
What imaginative solutions have you seen, or used to mitigate against flooding risk? Let us know in comments below.