Last night, a TV show on the ABC called Catalyst had a special on bushfires, something that should be of great interest to anyone who is in or near an area that regularly has them (ie, anywhere at all in Australia as well as California and maybe a few other places around the world).
For those who may not know, last year there were some horrific bushfires in Victoria and South Australia earlier this year. Entire towns almost completely wiped off the map as the bushfire passed through leaving few if any properties standing. Everyone in Australia was devastated, tempers flared in the aftermath and discussions could be heard anywhere and everywhere as to what went wrong and what should be done.
Catalyst decided to actually investigate the issue and rather than parroting the usual comments, they actually looked in to the science of bushfires. Fighting them, protecting ones property from them, and the psychology of managing and fighting one. For the moment the videos can be viewed at their website here (at least for those in Australia, I am not sure about overseas), as well as some very interesting web exclusives that I shall be checking out this evening when I get home.
The story certainly blew away a number of misconceptions I had about fires and the behaviours of them, especially in the second section about knowing the enemy and protecting ones home from them. One such misconception was in regards to the distance someone in a high risk fire area should keep between their house and the local flora.
I thought this was a combination of falling risk (trees/branches naturally) as well as fire. However, when it comes to bushfires the embers just blow in from anywhere between a few meters and a few hundred meters. Keeping a gap it would seem, does not help in any way shape or form when it comes to fires.
One thing I was dissapointed to see not discussed was in the first section when they were talking about hazard reduction burning. The idea behind HR burning is that you set controlled fires outside of the fire season to reduce the amount of scrub, tinder and kindling in and around the bush. This won’t have any affect on the main front of the fire as the flames and heat are way to high and easily sets alight the bigger thicker wood by itself.
One of the biggest threats to managing a fire though are embers. Whether they be leaves, tree bark, small branches or other bits of tinder on the ground or in the tree, these tend to light up and then travel in updrafts from the fire in to the air. The wind carries them well ahead of the main fire front (up to a few kilometers), where they eventually come down, light what they land on starting another front well in advance of the current front. Not only does this dramatically increase the speed the front travels, but it is also very dangerous for those fighting the fire. If firefighters and civilians are not careful, this second front can and has been known to entrap them.
In my mind if we can reduce the tinder for these embers to light, although we won’t stop a bushfire we will at least slow down the front as it won’t be jumping as often. Rather, it will travel in a slower more controlled and predictable manner which will be easier to control.
About six months ago I had quite a long discussion with a mate of mine @dreadpiratemick about this on twitter. He took the opposing view and sees hazard reduction burns as not having the affect I feel they do. This makes them nothing more than a useless polluting excercise. In the end neither of us were making any headway with the other so we agreed to just leave it at a stalemate. It would have been nice to get a little closer to a conclusion of this discussion through Catalyst, but I guess we will have to wait a little longer.