The Bushfire at Big Hill Brook
Bushfire in the karri forest (photo by John McKenzie)
In 1972 I was the Divisional Forest Officer (or in today’s jargon, ‘District Manager’)) of the forestry district with headquarters at Pemberton in the lower south-west of Western Australia. In this position, I was responsible for the day-to-day management (including bushfire protection) for the bulk of the beautiful, but fire-vulnerable karri forest. It was in those years that I learned just about everything I know about bushfires. Mostly I learned the hard way: in difficult situations on bad days. But there were also good days, and I was lucky to have many tough and bushfire-hardened field staff as my colleagues and mentors. This story is not so much about lessons learned, as about lessons powerfully reinforced. It was a mid-summer’s day I was out in Sutton State forest, east of the Warren River, with my Assistant Forester Jack (“Black Jack”) McAlpine. We were checking on the seedlings coming away in areas where logging and regeneration burning had taken place the year before.
A “wheatfield” of seedling regeneration coming away in cut-over karri forest
At about mid-day a message came through from DHQ on the two-way in Jack’s Land Cruiser: a bushfire had been detected on the Warren River near its junction with the Big Hill Brook. The column of smoke had been spotted and the fire pinpointed by cross-bearings from the Gloucester Tree and Beard Tower fire lookouts, and then reconnoitered and described by our District fire-spotter aircraft. I had a quick natter over the radio with my Duty Officer at DHQ and was pleased to hear that he had already dispatched the Quininup forestry gang and a Heavy Duty tanker to the fire and was arranging the dispatch of our D6 bulldozer. The gang would be there quickly, he said, but it would be at least an hour before the dozer could be expected to arrive. By coincidence, Jack and I were only about five km from the reported position of the fire, so we immediately drove there. We were at the fire within about 15 minutes of it having first been reported. It was a warm day, with a westerly wind. The Warren River runs through a steep, heavily forested valley in this area, and the fire had started right down on the river’s eastern bank. It had probably escaped from a campfire lit by a marron fishing party. By the time we got there the fire had already climbed up out of the river valley, and was about a hundred metres from where we pulled up on the nearest road. It was burning towards us through thick, long-unburnt karri-marri forest. Within about five minutes of our arrival, the Quininup forestry gang pulled in. This comprised Overseer Ron Farr and three men in the gang truck, and the Heavy Duty tanker with driver and swamper. All of these men were well-trained and experienced forestry firefighters.
A forestry fire crew at work in the karri forest with Heavy Duty tanker and hose The fire was coming at us in a long tongue. It was not a crown fire, but was burning strongly and noisily, advancing at a walking pace with flames about three metres in height. Jack and I conferred. We decided we would not attempt to move in to the fire through the heavy scrub, but wait on the road and make a stand at the point where the headfire would soon hit. It was not a very optimistic concept, but the only possible strategy at that moment. As the fire front arrived, we poured water onto it from the Heavy Duty, and did our best to tackle the tongues of fire which licked around the flanks and came out to the road. We were armed with shovels and fire rakes. It was hot and unpleasant work. Nevertheless, a point was reached when we were very close to controlling the headfire at the road, and starting to get a grip of the thing. If we could hold the headfire, the dozer could tie in the flanks when it arrived. But just at that moment Jack emerged out of the smoke and directed my attention to the bush behind us on the other (downwind) side of the road. About a hundred metres or more to the east, spot fires were starting up. Their source was a stream of burning embers floating high above our heads. As we watched we saw the spotfires flare and begin to coalesce into a new fire front, which in turn soon began to generate more spotfires.
“Black Jack” McAlpine, at work at a fire in the karri forest
We had done our best, but had lost this battle, and we were also now caught between two fires drawing at each other. These days, this is known to firefighters as the “Dead Man Zone”. We didn’t know the term then, but we knew it was not a good place to be. We wound up the hoses, loaded up our equipment, climbed into our vehicles and withdrew.
Strangely, you might think, neither Jack nor I was really worried. We knew that another kilometre or so ahead of the new headfire there was another track and this had been the edge of an aerial burn we had done two years previously. Thanks to this burn, beyond the track was a thousand hectares of forest in which the flammable fuels were thin on the ground. This was the place we chose to make our next stand (by now with the assistance of the D6 bulldozer, which arrived just then).
Sure enough, when the fire came roaring out of the thick bush and reached the 2-year-old fuels in the aerial prescribed burn, it dropped right down. Instead of the flames reaching up into the forest canopy, we could now comfortably step over them, as the fire trickled around in the thin layer of leaves. Within 20 minutes or so, the headfire was easily contained. Not only did the fire burn only patchily in the light fuel, it now threw no spotfires.
By late afternoon, with the assistance of newly-arrived forestry gangs from Northcliffe and Manjimup and another small bulldozer, we had a containment line around the fire, right back to the top of the Warren River valley. There the crews had to cut firebreaks with shovels down to the river, as the fire edge was too steep for the bulldozer. Mopping up of the fire edge was completed the following day, and the day after that Jack undertook a thorough check, walking the entire edge, and declared the fire “safe”.
This small drama might be regarded as just a footnote in firefighter history. But to me it was a graphic illustration of the need for a mosaic of fuel reduced areas within the forest. This fire was rapidly detected, and the weather conditions were not particularly savage. Experienced and well-equipped firefighters and trained fire commanders were on the scene within minutes. But we were unable to stop it while it was burning in heavy fuels and generating spotfires ahead of the main front. Once the headfire reached the fuel-reduced area, created by planned prescribed burning, fire suppression became simple and safe.
An aerial prescribed burn in progress in the karri forest – mild intensity fires are burning away the accumulated bushfire fuels Photo thanks to Nikki Rouse
Some people oppose the need for fuel reduction burning, maintaining that the answer to the bushfire threat in south-west forests is simply to have a better detection system and huge numbers of firefighters on constant standby throughout the forest. The fire at Big Hill Brook demonstrated otherwise. We had excellent, rapid detection and a crew of firefighters quickly on the job. But even the best firefighters will not succeed against a high-intensity fire burning in long-unburnt fuels generating spot-fires down-wind.
I was remembering all this the other day when I read an article (in an international journal) by two professors from WA’s Murdoch University, Neil Enright and Joseph Fontaine. They claimed that “there is no evidence” that fuel reduction burning has any benefit in the control of forest fires. As I read this, I thought grimly to myself that they might have had a different view if they had been with Jack and me that afternoon in the karri forest back in 1972.
There are also those who maintain that if only we had the modern fleet of water bombers available back then, things would have been different. The people who say this have never watched water bombers trying to suppress an intense fire burning in heavy fuels in the karri forest. Put simply, they never win.
The current system of bushfire management in WA is not perfect, with some steps forward and some back over recent years. But at least it is a system in which the consequences have been identified and weighed-up. In other words, it is a system that has been thought-through. Moreover, it is based on sixty years of scientific research and the real-world experience of generations of firefighters, including the experience of Jack McAlpine and Ron Farr and his gang, with the Fire at Big Hill Brook.