Sheltering with the Wind-Blown Horse – Living Through Cyclones

Cyclones are generally considered a tropical weather phenomenon.  However, as I write this series South-East Queensland, where I live, has been dealing with the impacts of Tropical Cyclone Alfred, which made landfall just north of Brisbane and affected communities from Hervey Bay to Northern New South Wales.  As a result, I’ve decided to bring this article to the front of the queue while cyclones are on people’s minds.

This is not entirely unprecedented – cyclones hit this area in 1954 and twice in 1974, the first in 1974 causing devastating flooding.  However, climate change makes such events more likely.  Evidence so far seems to suggest that cyclones are becoming less frequent but more intense, longer lasting and travelling further south.  Cyclones are complex, unpredictable weather systems but essentially they form over the ocean during the summer months when there is the right combination of atmospheric and ocean conditions.  Then they can be sustained for days or weeks as long as the ocean temperature is above 26.5C.  As climate change warms our oceans, the locations in which cyclones can remain viable extends away from the equator towards the poles. 

Once cyclones cross onto land (not all do) their intensity tends to drop rapidly, and they turn into low pressure systems.  There are three main risks associated with cyclones - wind, flooding and tidal storm surge.  Storm surge only affects the area within about 100m of the coastline where waves driven by high winds can swamp anything in their path.  Winds are mainly a factor along the coast and hinterland (Zones B, C and D as discussed below) as cyclones tend to rapidly lose strength as they move over land.  Floods can affect a far wider area as the cyclone transforms into a low-pressure system which can dump large quantities of rain over a far larger area.  Since social and affordable housing is unlikely to be located directly on the waterfront, and flooding is addressed in a separate article, I am focusing here on the risks from wind.

I don’t expect I could say much in this article that will be new to anyone in tropical Australia, where cyclone readiness is a normal part of life.  However, for those who live and work in the areas to the south of the 'normal' cyclone zone, Cyclone Alfred has provided a timely warning. We were fortunate that this time it turned into a tropical low before it crossed the coast, but there was still significant damage along the coast and flooding further inland. It showed some significant ways in which we in SEQ and Northern NSW, and no doubt others in similar areas, are unprepared for the possibility of cyclones. We don't know how wind-resilient our homes are, we are novices in cyclone preparation and not sure exactly how to interpret the large quantities of advice we were suddenly receiving, and safe refuges are in short supply as few of our public buildings have been built to the safe standard. Rather than counting our lucky stars that it wasn't too bad and going back to business as usual we need to take this as a reminder to get ready now, because there will inevitably be a worse event in the future.

Cyclone Risk

Cyclones are intense storms that affect the coastlines of tropical and sub-tropical areas in summer. The cyclone risk areas in Australia are defined for construction purposes under The Australian/New Zealand construction standard for wind (AS-/NZS-1170-2-2021).  This divides Australia into four zones. 

• Zone D is the area of severest cyclone risk, and incorporates the coast on the westernmost extremity of Western Australia. 

• Zone C is the cyclonic zone and includes the area within 50km of the coast of Queensland north of Bundaberg, all of the Northern Territory coast and the Western Australian coast north of about Carnarvon. 

• Zone B is the intermediate area where there is risk from weakened or ex-tropical cyclones, which extends 100km further inland of the cyclonic areas and to the south as far as the central coast of NSW and to Green Head in Western Australia.   

• The rest of Australia – basically anywhere to the south of these areas or more than 150km from the coast, is Zone A, which is not considered subject to cyclone conditions although it could experience strong winds for other reasons. 

I can’t find an ‘official’ map of these zones but I’ve included one here taken from an ABC article.  Within these areas the cyclone season is broadly considered to stretch from 1 November to 30 April although these dates should not be taken as precise.  Cyclones vary in strength from Category 1, with an average wind speed of 63–88 km/h and gusts up to 125 km/h, up to Category 5 with average wind speed greater than 200 km/h and gusts greater than 279 km/h.  A Category 1 cyclone may only do a small amount of damage, whereas Categories 3 and above can be devastating for communities. 

The number of cyclones across northern Australia varies from year to year and it’s impossible to predict too far in advance when they will form.  Their path of travel is also hard to predict too far ahead.  Hence if you live in a cyclone risk area it is worth keeping one eye on the weather reports.  If you’re new to cyclones, have a read of the Bureau of Meteorology’s Cyclone Knowledge Centre to get up to speed on what cyclones are, how they are classified and how the BOM tracks and reports on them. 

As mentioned, this is the historical pattern of cyclones.  In a changing climate, it does not pay to be too backward looking.  The scientific evidence suggests that as the atmosphere and oceans warm, cyclones will occur further from the equator (that is, further south in Australia) and be more intense on average.  This then needs to flow on into our planning and building responses.

Building Standards

There is a specific set of building standards that relate to durability in the face of wind (AS/NZS-1170-2-2021) which are mandated in the National Construction Code.  There is also a specific wind load standard (AS 4055) for low-rise housing (one or two stories).  These are detailed technical sets of construction standards for different wind zones and are not designed for the general reader – leave them to the experts.  A more readable guide is provided by the Queensland Reconstruction Authority’s Cyclone Resilient Building Guidance – follow the link below to see a copy. 

Wind damage comes through three different pathways.  Firstly, if a building is not strongly enough constructed (either through using materials that are too flimsy, or not being firmly enough fixed together) parts of the building can simply be demolished by the force of the wind – this is how you see things like whole roofs blown off, or walls knocked over.  Secondly, vulnerable parts of the home can be damaged by debris carried by the wind – this particularly affects windows but can also include wall cladding, flashings or other fixtures.  Thirdly, water can be blown into the house either through holes created by wind or debris, or where gaps and joins are not well enough sealed. 

Housing in cyclone zones will have been built according to whatever building standards were in force at the time of construction. The first specific standards for cyclones were introduced in the Northern Territory in 1975 in the wake of Cyclone Tracy, and in Western Australia and Queensland in the mid-1980s.  This doesn’t mean the housing built since that time will necessarily be ‘cyclone ready’ as subsequent deterioration or unskilled maintenance can compromise safety, so any housing should be inspected from time to time to make sure.  Any housing built before these standards came into force will need to be carefully inspected and upgraded to meet the standard wherever possible.  Upgrades will need expert guidance but will generally focus on strengthening walls and roofs and the connections between them, improving air and water tightness, replacing any fixtures that present a hazard during a high wind, and installing cyclone screens or shutters on windows. 

What of those properties outside the designated risk zones?  Up to now they have not been required to build to the same standards, and it is likely that building regulations will take a while to catch up with the reality we are already starting to see.  If you are a social and affordable housing provider in South-East Queensland, Northern NSW or the south-western coast of Western Australia, any housing you own now or acquire in coming years will face increasing cyclone risks, and you would be wise to start paying attention to cyclone risk now.

Preparation

Communities normally get at least a few days warning that a cyclone is coming and this gives time to prepare as best they can.  I have included links below to the advice on preparation provided the Queensland, Western Australian and Northern Territory governments.  In summary, the following are the key elements of the advice:

• Removing or securing any debris or outdoor items that can be carried by the wind. 

• Securing or protecting windows and any other house infrastructure that could be damaged.  For windows, this could include fixing plywood over the outside of the windows or, if this is not possible, taping plastic to the inside to limit the entry of water if the window is broken. 

• Identifying the best place within the house to use as a refuge in case the house is damaged – this is likely to be a room without external windows or with minimal window area in which to wait out the storm.  A bathroom is the most likely candidate.

• Assembling emergency supplies which would include enough water and non-perishable food to last up to a week, lights and spare batteries in case the power goes out, power banks for mobile phones, a battery-powered radio to follow updates on local ABC stations if phone and internet are out of action, and a first aid kit including supplies of any essential medications.

• Making sure you know the location of safe emergency shelters in case you need these.

As is the case with other emergencies, your tenants may be at particular disadvantage in relation to these preparations, especially if they have disabilities, are older or have little family support.  Your organisation’s emergency planning should include a process for making contact with vulnerable tenants to make sure they are aware of the approaching danger, know how to prepare and have the support they need to do so.  You also should be aware of sources of support, including what capacity you have to directly help tenants if they have nobody else on hand. 

Aftermath

After a cyclone, or any major disaster, comes the clean-up, then the recovery.

The clean-up will begin as soon as the event is over and will, for the most part, be rapid and labour-intensive. This basically involves cleaning up the mess - reconnecting utilities, re-opening streets, disposing of debris and damaged goods and making the community as safe and livable as can be in a short time.

The recovery can take a lot longer - sometimes years. This will involve repairing more serious damage - restoring or demolishing and replacing unlivable homes, fixing damaged infrastructure and so forth - along with the necessary and sometimes difficult process of negotiating with insurance companies and distributing a substantial amount of government and donated recovery funds. In this phase it's also important to pay attention to mental health as the trauma of the event can have significant psychological impacts that can emerge over time.

As a housing organisation, three things are most likely to have an impact on you.

• You may own or manage homes that have taken significant damage, and it will take time and resources for you to assess the damage, negotiate with insurers and get the repairs done.

• Your tenants may have had their homes damaged to the extent that they are unlivable, in which case they will need alternative housing for as long as it takes to repair. This period may be significant, and it may be better for both you and your tenant if they can be permanently relocated - however, this will depend very much on individual circumstances, and flexibility is the key here.

• The trauma of the event may mean that some tenants are unwilling to stay and seek help with transfers either out of the community altogether, or to a new location within the community. This may apply even if the tenant's housing has not been rendered physically unlivable.

• If a significant proportion of housing in the community has suffered damage there is likely to be considerable demand for temporary housing and an overall shortage of housing in the community – this can persist for some years after a serious event.  In this case, as a housing provider you may be able to play a substantive role in the recovery process by facilitating the supply of replacement housing, including rapid deployment of modular of factory-built homes either as temporary or permanent replacements for what has been lost.

These events tend to galvanise community and government energy and resources, and this can be a good opportunity to leave the community, including its housing, better prepared for the next event. 

Resources

The BOM’s Tropical Cyclone Knowledge Centre is a good source of basic information about cyclones, warning systems and the nature of cyclone events over history.

This article from Tempests and Terawatts (written by Michael Mazengarb) summarises the scientific evidence on the effect of climate change on cyclones. There's also this report from the Climate Council for more detail.

The Cyclone Risk Map comes from this article.

The Queensland Government’s Cyclone Risk information is at Get Ready Queensland. The NT Government’ equivalent can be found here.  The WA Department of Fire and Emergency Services provides resources for that state including specific information on preparing for a cyclone.  

For organisations, ACOSS has a good disaster resilience framework you can apply to help you prepare.  For community level planning for vulnerable people, Collaborating4Inclusion has a great set of resources focused on homelessness and other vulnerable community members, which you can use across the community. There are lots of great resources for individuals to prepare for disaster.  Here’s one from the Red Cross, while the National Emergency Management Agency has published a set of links to each State's and Territory's planning resources.

Queensland Reconstruction Authority has published a pair of easily-understood guides, Cyclone and Storm Tide Resilient Building Guidance for Queensland Homes, most of which will be equally applicable to homes elsewhere. 

You can pay a substantial sum of money for the Australian Standard that relates to high winds here - it's only really useful for design and construction professionals.