Phil Brown, European regulatory marketing manager at Pilkington United Kingdom Limited, part of the NSG Group, outlines the many aesthetic and operational benefits of using specialist glazing as an alternative to concrete flood defences.
Flood water damage can be devastating. Whether it’s flash flooding from heavy rain, riverbank overflow or a storm surge, the effects on property, and health and safety, can be catastrophic.
Around five million people live in flood risk areas in England and Wales and, as a result, permanent defences have become a necessity to protect the buildings, businesses, and homes in the worst-affected areas.
The question of how exactly these defences should be designed and implemented is largely a challenge for engineers. However, there is a vital aesthetic component to the implementation too.
The way flood defences look is particularly important given the nature of the places where they are typically needed – where the built environment meets natural waterways. These places – towns sitting by lakes, rivers, or the sea – are also typically celebrated for their scenic beauty and they are often popular destination for tourists.
If flood defences are too visually imposing, they can easily detract from the visual charm of a place. In some cases, local planning authorities can even prevent construction of defences that are too visually imposing. A good example of this happened recently in Lancashire.
“Brutalist appearance not appropriate”
In April this year, Lancashire County Council landscape specialists called for changes to a large flood defence scheme to line parts of the river Ribble with concrete walls.
Despite the project being underway and preparations for construction having already taken place, Lancashire County Landscape Service “strongly recommended” a redesign, describing visualisations of the proposed fortifications a “retrograde step” compared to the defences currently in place.
According to the council’s report: “The pre-cast concrete walls would have a very simple, almost ‘brutalist’ appearance, which is not appropriate for the area’s local landscape character.”
A big part of the challenge when it comes to creating aesthetically sensitive defences is the height of the walls needed to provide protection from increasingly extreme flooding events. Where a 600mm wall might be installed with relatively little noticeable impact on any given view, a 1500mm barrier will be much more imposing.
In some cases, this can be overcome by raising the height of paths on the non-flood size of the wall, but the groundworks involved in this approach can often prove prohibitively costly.
So how can flood defence installations be made less visually impactful without compromising on its vital primary purpose of protecting people and property from flood waters?
One option is to make the upper sections of the defences temporary, using wooden boards placed between slotted posts, for example, which can be removed during seasons when there is less risk of floods.
However, there are drawbacks to this approach. As well as the ongoing cost and practical challenges of installing and removing the defences, there is also the risk of an unexpected flood striking at a time when the barriers are not in place, leaving no time for them to be put back.
Thankfully, in the past few years, an innovative new option has emerged providing designers with a way to tick both boxes with a permanent installation that still allows almost uninterrupted views of the natural environment. That is placing engineered glazing atop lower flood defences.
Tough and beautiful
By placing laminated safety glass panels between strong steel or aluminium posts that are embedded in concrete foundations, it’s possible to create defences that are more than strong enough to contain flood waters, while also allowing visitors and residents to keep enjoying the views.
The visual appearance of the panels is more akin to the glazed balustrade on a terrace or balcony than to concrete walls, avoiding the risk of making previously beautiful spaces feel overly fortified or boxed in.
Glazed defences are gaining ground around the UK, with several coastal and riverside installations having been created in recent years.
One such project is the flood defences along the river Kent as is flows through the picturesque town of Kendal in Cumbria, for which construction has started and is expected to be complete by the end of summer 2023.
The glass used to create the flood walls is a bespoke creation developed in collaboration between Pilkington UK, and chemical and materials manufacturer Kuraray. The system has been designed and will be installed by flood protection experts, Flood Control International.
The specialist installer has designed the system using glazing built up of alternating layers of glass and interlayer to create a 35-millimetre laminated toughened glass. The use of toughened glass helps ensure the glass is not at risk of thermal fracture on sunny days. Modelling was carried out to ensure the glass panels have the capability to safely hold back water in the event of water levels rising, as well as withstand the impact from debris carried by flooding.
By using Pilkington Activ™ self-cleaning glass, which reacts with natural daylight to break down and loosen organic dirt, the council will save money on maintenance while ensuring the glazing remains free from build-up of dirt. This will ensure that locals and visitors have a clear view of the riverside that runs through the centre of the town as well as its distinctive buildings.
Council leader Stephen Parnaby said: “We could have raised the concrete wall further to help manage the flood risk but we wanted to do something more sympathetic along a river front which is popular with visitors.”
The sad reality is that waterside locations across the UK are going to need to consider installing defences as climate change makes severe flooding events increasingly frequent occurrences.
High-strength glazing will be a useful tool in the designer’s kit when it comes to protecting these much-loved locations without compromising on their aesthetic beauty.