Flood Resilience: Designing on the Water’s Edge

Flooding and coastal erosion are threatening to destroy more than 5 million properties in England—a number that is expected to double over the next 50 years, according to the U.K. Environmental Agency.

If infrastructure is not adapted, this flooding and erosion could cause considerable disruption and economic damage to these areas.

To improve risk management in these areas, London-based Baca Architects have been working on the LiFe (Long-term Initiatives for Flood Risk Environments) project. The project aims to identify ways in which the means of managing flood risk can be integrated to help meet objectives for development while driving zero-carbon, high-quality, sustainable development at a minimal cost.

“It's becoming increasingly difficult to not venture into the floodplain and, as a consequence of that, we've had to start to design buildings that can mitigate flood risk,” says Richard Coutts, founder of Baca Architects. “The majority of our work is actually in existing urban areas that are more susceptible to flooding.

Baca’s approach is a nondefensive approach to flood mitigation. Rather than trying to hold the water out by flood defenses, which will ultimately be overtopped, the team at Baca Architects believes you can create a safe environment to let water in via managed means.

“If you're running in the river's edge you can use floating, and as you move a little bit farther inland you have the option of either creating a stilted property or we've developed a housing type project called the Amphibious House,” Coutts says.

The Amphibious House was built on a flood-prone island on the River Thames. It’s built at the ground level, and when conditions are dry it rests on the ground. In the event of a flood, however, the whole house can rise with floodwaters and then recede.

Working with Mother Nature

Coordinating projects like the Amphibious House in flood zones differs from approaches taken by conventional architectural projects.

First, each project that occurs in a flood zone must be designed based on its unique environment. According to Coutts, the project team should start by getting an understanding of how much space you need to make for water and then plan the development around that.

“That's a consequence of understanding how Mother Nature wants to work and instead of trying to fight against it, you try and work with it,” says Coutts. “You can't do that after you've designed the scheme, it has to be there from the beginning.”

Working around Mother Nature, however, doesn't mean the development shouldn't be in line with its surroundings or the neighborhood in which it will be found.

For example, for Baca Architects' recent flood-resilient development project in Stratford-upon-Avon, England, the team set the development about 1.6 meters (5.25 feet) above its normal ground level. They then developed the buildings stepped in sections, so that the whole development fits contextually with the neighboring properties. There is also a communal garden system, which is designed to flood.

“The water can flood underneath all of the buildings and be absorbed in all of the landscape,” said Coutts. “That works as a whole system. By building new developments, you can actually create betterment not just for that site, but for the adjacent sites.”

In addition to letting the water lead the way, you need to bring in experts. A hydrologist can provide background information about the flooding in the area and help the architect involved understand how flooding works and how to compensate for how the land moves during flooding. Engineers may also need to be part of your team to help design details of the foundation and below-ground drainage.

Finally, you may need to rethink how traditional infrastructure is incorporated into the project. For example, you may need to include
nonreturn valves to prevent backflow from entering the home from sewage systems and installing the electrical system from the top down instead of from below so it does not get wet in the event of a flood.

Insurance Sector Driving Regulation Changes

“The major challenge of building a flood-resistant house,” Coutts says is “there has not been a huge incentive to do it. Most people only modify their homes after a flood event.”

It’s a mindset that the team at Baca Architects is working to change.

“If you look at the insurance sector, if you're a nonsmoker and you exercise regularly, your insurance premiums are reduced,” he says. “Until very recently the insurance industry was quite relaxed in terms of providing wholesale flood insurance. Over the last decade, because of the increased frequency of flooding, the industry has become quite concerned about offering every household universal cover.”

He believes that because of this, any changes to the industry will now be driven by the insurance sector. In Europe, for example, Coutts said that flood resilience measures have started to slowly creep into building regulations.

“If you build new houses in certain flood locations, then there will be a requirement to provide the highest standard of construction measures,” he adds.

In the U.K., the regulation is not quite there yet, but the changes in other countries could be a warning signal for managers on these projects. Coutts said he is seeing several new developments that are in flood zone two, but there is no requirement to include flood-resilient measures within those efforts.

His team would argue, however, that by spending just a few £1,000 (1160.65 USD) more in construction you could make those properties more resilient.

“Actually, 20 to 30 years’ time from now, when there's a major flood event, not only is that a saving in terms of people being displaced or disruption to business, but also then there's also a saving within the insurance sector as well," Coutts says.

Ultimately, Coutts believes that when handled correctly, water can be more of an asset for property development projects than a threat.

“Small lake houses that overlook landscaping generally attract a higher premium," he says. “You've got to turn this sort of whole position on its head and create a wonderful environment for that. That will mean people will have more exciting places to live, and those places stand a better chance of being flood resilient."

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