In light of the Queensland and New South Wales floods, we have been talking a lot about how to build your home with flood resilience in mind, and how to clean up after a flood event.
Flooding can result in significant damage to your property that can be costly to fix afterwards. To prevent this cost, as well as the threat of injury and loss of life, it is important to think about flood protection well in advance.
There are a number of ways to improve property resilience against floods, including lifting the building above the floodwaters, buildings with concrete or brick, and building physical barriers to protect communities and properties – such as floodgates, levees and seawalls.
- Read: How to improve your property resilience against floods
- Read: How to clean mould and avoid serious health risks
“Things like levees and seawalls are hard engineering structures that prevent flooding,” explained Dr Tayanah O’Donnell, partner in Deloitte’s risk advisory, climate and sustainability team. They are “often thought of as useful adaptation measures when it comes to flood preparedness”.
Physical flood barriers are a very important way to mitigate flood risk, and one that many local governments are crying out for. But while they may seem like a no-brainer to providing a high level of protection against floodwaters, they have both advantages and disadvantages.
Types of flood barriers:
There are several types of flood barriers depending on the area that is at risk, and the level of protection sought.
Levees, dikes and berms: these are embankments constructed to hold back water from a river, lake, or the ocean.
Flood wall: a watertight perimeter wall around an area reinforced to hold the pressure of the water. Flood walls include a gate that looks normal, but is in fact designed to keep waters out.
Sea wall: A seawall is a massive concrete structure usually placed along a stretch of shoreline at urban beaches.
Inflatable dams: These are watertight portable tubes that can be transported to the location and then filled with water. The weight from the water prevents flood waters from inundating the area. They can be removed after the flood event.
Benefits of flood barriers:
- Protects the area from flood damage without significantly changing the structure it protects
- Stops water pressure from causing structural damage to the home inside the protected area
- May cost less than rebuildings, relocating or elevating the structure
- Reduces the physical, financial and emotional damage from flood events
Disadvantages of flood barriers:
- Displaces water so may cause more flooding in other areas adjacent to the protected area
- May have significant upfront installation costs
- May fail or be overtopped by big floods or long-term flooding events
- They may require storage and may not be available in all areas
- Requires regular maintenance
- Might restrict access to the property
- May not reduce flood insurance premiums
- Does not prevent the need to evacuate during floods
- Does not protect from other indirect damage, such as landslides and mould.
- Flood barriers function under assumptions of current weather systems that are now being significantly altered by climate change. In other words, while levees, flood gates and seawalls are an effective adaptation measure, they need to be built fit-for-purpose for the future.
- According to Tayanah O’Donnell these might create a false sense of security, “especially in light of the enormity of the now locked-in climatic changes we will see in our climate systems over the coming years and decades”.
