Floods are a relatively common natural disaster in Australia, yet over the decades, building codes around the country haven’t been revised to fully mitigate against the damage caused by flooding. Unlike other natural disasters such as cyclones, bushfires, and earthquakes, the country hasn’t fully embraced the lessons that we’ve learned from past floods. In response to the disaster of Cyclone Tracy in 1974, the whole country adopted new wind codes, which have saved countless buildings from damage during subsequent cyclones. Similar regulations have been put in place regionally and nationally in the wake of bushfire disasters, and in anticipation of earthquakes, but measures regarding floods are lagging behind.
In stark contrast to the progress made to protect against other natural disasters, the use of materials that are easily damaged by water has grown exponentially (including plasterboard walls, composite timber beams, chipboard kitchens, and plywood bracings), all of which are allowed in the building codes for flood plains. This creates the likely scenario for buildings effected by flooding events either needing to be gutted or completely demolished, even if they’ve withstood the winds of a cyclone! The building industry has fought back against recent attempts to amend building codes to protect structures against unnecessary flood damage, sighting unbearable costs. However, experts have found that flood-resistant buildings would only cost 5% more than the cost of ordinary buildings.
Hazards that aren’t fully considered in flood risk plans
Most floodplain management plans overlook key considerations that need to be fully weighed when assessing flood risks. The core flood risks (the risk to life and over-floor flooding) are considered in most plans, but numerous non-core risks are almost always ignored. Currently, Australia doesn’t have nationally adopted standards to guide planners, developers and builders on what levels of non-core flood risks aren’t acceptable, so many of them end up ignoring the non-core risks altogether.
In comprehensive flood risk plans, flood duration should be fully considered. If a building or an entire community is cut off by flood water for a long time, the cost (in terms of disruption to businesses, supplies needed for rescue operations, and provision of medical services) could be great. The consequences that result from flooding are often generalized, but in a good flood plan, each consequence should be weighed differently. For example, if a hospital is put out of commission because of a flood, the cost to the community will be greater than if regular commercial operations are closed.
Possible mitigations against unnecessary loss of life and property damage
The proper management of flood is only possible with a concerted effort from all stakeholders, including the governments (national and state), city council planners, developers, and homeowners. The good news is that state governments have been developing newer and more effective floodplain management strategies. For instance, the Victorian Government has come up with the following new flood management measures: Arrangements for sustainable management of levees; Factoring climate change in new flood risk assessments; Ensuring warning systems are well maintained so that early signs of floods aren’t missed.
Similarly, local councils are coming up with flood mitigation solutions that may apply within their jurisdictions. To mitigate against both core and non-core flood risks, the Moreton Bay Regional Council came up with the following suggestions for developers: They could create a warning system, an evacuation plan, and a community education program to ensure that people are able to vacate flood zones as fast as possible; Developers could ensure that people who fail to evacuate early are still able to walk to flood free areas before flood waters start to rise; Developers could include a flood-free refuge within buildings, which would be equipped with all basic necessities such as water, food, and an emergency power supply. The refuge would also be accessible in case there’s need for medical evacuation; They could design buildings whose ground floor levels are above peak flood levels in the area.