theoutdoortype (theoutdoortype) wrote in aus_outdoors,

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Bushwalking and bushfires

This post is mostly culled from a thread on the bushwalk Tasmania forum. Some of the material was from me, some from others; I’ve distilled both into a single post.

In her famous poem, A sunburnt country, Dorothea McKellar spoke of the Australian landscape, and “her beauty and her terror”. Anyone who’s ever confronted a bushfire will know exactly what she meant.

The extraordinary beauty of the Australian bush is what drives us to pursue this strange pursuit, bushwalking, but when it erupts in bushfire, then we truly witness her terror. To be confronted by bushfire when out walking, far from roads or communication, then the fear would be paralysing.

What should a walker do, when confronted with a raging bushfire?

The first step, as always, is to plan ahead. Be aware of days of extreme fire danger. These are generally hard to miss – ads will be all over the TV and radio, although broadcast warnings are usually fairly general. To ascertain the fire risk more specific to the area you plan to walk in, you should be able to find information on the Net. It would be best to check with the local ranger.

Also pay close attention to weather forecasts for the area, in the day/s you’re planning to walk.

If you are out bush and you do see fire or smoke nearby, the important thing is not to panic, but to begin to plan ahead.

Smoke can tell you a lot of things about a bushfire. The size of the fire, for example, or the direction it’s travelling. Colour is also important: Light coloured smoke indicates a fire that is burning relatively cooler, and consuming grass and dead foliage. Large, dark billows of smoke are a sign that a fire is burning hotter, and consuming denser wood.

If a fire is likely to be burning near you, it is important to try and remain downhill from the fire. Fire burns much faster uphill: for every 10 degrees of upwards slope, the rate of spread of the fire will double. So while there may be a temptation to stay on higher ground, the better to observe the fire perhaps, when the fire suddenly races uphill towards you, you’ll have little time to escape.

The obvious converse of this is that fire advances much slower downhill, giving you much more time to escape or seek shelter. Be careful, though, as narrow gullies and holes can easily become traps.

Mega-fires, like the recent Black Saturday fires in south-eastern Australia, are fortunately rate (generally occurring on a roughly 30-year cycle). With a less severe bushfire, the fire front may only be a few hundred metres wide. In this situation, and particularly if it is moving uphill towards you, it might be wise to try to move perpendicular to (ie. across) the face of the fire and, if possible and the flames are low, get back onto burnt land across the flank of the fire.

The spread of a fire is affected by many things, including topography, but one of the major factors influencing a fire is wind. Generally – although this is a generalisation only – a fire will move in the direction of the wind, so a fire is usually characterised by a head, also called a front or face, usually the hottest, most active part of the fire, which burns along, leaving a pair of long, much less active flanks.

It is important to keep this characteristic of fires in mind, after the main front has passed. If a wind change arrives, the long, calm flank of the fire may suddenly roar up into a long, dangerous front. Keep the weather forecasts in mind!

Another feature of bushfires are spot fires. Spot fires occur in windy conditions, when embers and small burning debris rises on the hot convection currents of the fire, and is then blown ahead of the main fire front. So even though the main front of the fire may still be some distance away, spot fires may spring up seemingly out of nowhere, creating smoke and confusion.

The most important thing to remember about surviving a fire is that radiant heat is the killer.

Radiant heat is the heat that, well, radiates directly from a fire (as distinct from convection - heat carried on air currents - and conduction). If you’ve ever sat near an old-fashioned bar heater, it’s the radiant heat that you feel. Bushfires can generate tremendous amounts of radiant heat. Radiant heat reduces rapidly with distance (in an inverse-square rule, to be precise).

The important thing with radiant heat is to shield yourself as best you can. Even though it may run counter to instinct in hot, summer bushfire weather, this means covering up exposed skin. Have a long sleeved shirt and long pants. If possible, avoid wearing nylon or other synthetic clothing. Synthetics burn easily, some can even melt onto your skin.

Cotton (treated with a fire retardant like Proban) is the material used by Australia’s bushfire fighters. Cotton does have its problems, however, as a material for bushwalking clothing. In the likely situation that you get wet and cold, cotton will get you much colder much faster.

Wool is the best option, all round, for bushwalking gear. Not only will it keep out water and cold better, wool is also naturally fire resistant.

As the fire front approaches, if you can also find an object to shield yourself, such as a fallen log, do so. Other shelters might be a running stream, wet gully, lakes or even the ocean. A good option would be to find a creek with a fallen log in it! Also look out for bare, rocky outcrops.

Lie face down, to keep your face covered and to try and find cooler, smoke-free air close to the ground.

Stay in your chosen shelter until the fire has passed and cover any exposed skin with clothing, soft earth, anything at hand to shield you from the radiant heat.

As a last resort, you may be able to run through low flames onto burnt ground. Be aware, though, that freshly burnt ground can be very hot. It would help if you have boots with heat resistant soles. Certainly adequate footwear is a must for bushwalking, in any circumstance – no thongs!

Also keep up your hydration. It's very easy to succumb to heat exhaustion. I was at the 2003 North-East fires, and I know that on one day alone I drank 6 or 9 bottles of Powerade and 3 bottles of plain water. I still got a mild touch of heat exhaustion.

Here are some further links on the subject:
Bushfire safety advice for bushwalkers
Before You Walk: Tasmania's Essential Bushwalking Guide & Trip Planner (PDF, includes some information on bushfires)

Thanks to red tag, Wet, the_camera_poser, tastrax, woka, Son of a Beach and Robbo, who all contributed to the original bushwalk Tasmania thread that inspired this post.
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