Saturday, February 14, 2009

The Blame Game.

It was inevitable the blame game would start quickly and it was also inevitable that it would be "the greenies" who would be blamed for the tragic bushfires in Victoria, it was also inevitable that the armchair experts wouldn't identify which particular "greenies" they were nor would proof be offered as to what it was "the greenies" did. But all that doesn't matter but finding someone to blame and pointing the finger is all that really matters here, there's no point whatsoever letting the facts get in the way of rabble rousing.

I just posted the following on a forum I frequent and to save retyping I've shamelessly copied and pasted my own work, it will probably give you a better insight into things than perusing the daily fishwrappers:

Had a quick skim of this report: ... report.pdf, one of the things which caught my eye is that a fire intensity of greater than 3500W/m2 is regarded as uncontrollable. A fuel load of roughly 500g/m2 under a Forest Fire Danger Index (FFDI) of 100 put out this sort of energy. That's a very low fuel load conditions last weekend in Victoria led to a FFDI of 300, which is fairly unheard of (at least not in those areas anyway), under those conditions fire on a dry lawn is pretty well uncontrollable (and I have seen conditions like that). Unless you've got a completely scorched earth under those conditions any fire will be difficult, if not impossible to control.

Another factor is that many areas where the fires have burnt are dominated by Wet Schlerophyll Forest, what this means is that there's a Eucalypt overstory but the under and mid story are dominated by rainforest plants and while there is a lot of growth and vegetation in there it is generally too moist to burn in anything other than small patches. The only way to get it to burn is for it to dry out, on the rare occassions it does dry out the fuel load is very high which means that there will be a high intensity fire.

Hazard reduction is useful, however it only a reduction of the hazard and not an elimination of it, it's quite possible for an area to have a hazard reduction burn in winter or spring and still carry an intense fire later in the summer. This was the case of the January 1994 fires in Port Stephens, a fire started on the side of the road (probably from some idiot tossing out a ciggie butt) where the Water Board had carried out a hazard reduction the previous winter, the first tanker was there only minutes after it started, it was very low humidity, high winds and temperature in the high 30's. I was on the first truck there, under normal circumstances with the short time taken to get there and the low fuel load we'd have gotten in out in a few minutes.

Under the conditions of the time it quickly jumped the road into tall heath and it was off. A few days later when we thought we had the fire just about locked away we got our morning weather report predicting temperatures in the low-mid 40's, high westerly winds and humidity of 8% (I found out later humidity had gotten to zero), just after lunch it went off. Areas we thought we'd secured a couple of days beforehand (backburning, full mop ups) had the fire go through again, we heard the fire, we saw the fire, got choked by the smoke and the front had passed us, a very terrifying 30 seconds or so.

I would imagine there'd be worse stories to tell from the Victorian fires, if you want somewhere to be fully fireproof that's easy, concrete everything within a 2 kilometre radius and have no plants whatsoever in your garden, if you want to live in areas surrounded by bush then you have to accept that there is a good chance there will be fires and manage and plan accordingly. With the whole "tree change" thing there are many people moving into these areas with no experience of fires, no knowledge of the precautions needed. But unfortunatelly under extreme conditions, extreme things happen and sometimes no matter how well you prepare it may not be enough.

No comments: