By Roger Underwood
In the wake of my recently published analysis of the effectiveness of water bombing, I have received an interesting letter from a former employee of the Department of Conservation and Land Management in WA … these days rebadged as the Department of Parks and Wildlife.
His story concerns a fire in the nature reserve at Mount Manypeaks, located about thirty kilometres east of Albany on the WA south coast. This is considered one of the State’s most important reserves, being home to the Noisy Scrub-bird (Atrichornis clamosus), one of our most endangered species. The Noisy Scrub-bird (NSB) was for many years considered extinct, but then a small remnant population was located at Two People’s Bay nature reserve in the 1960s. From here, birds have been successfully translocated to several suitable locations, including Mt Manypeaks, and this in time became the principal population of the species. Since they were originally rediscovered within bushland that had been long-unburnt, wildlife scientists concluded that the bird (which is ground-dwelling) would only survive if fire was permanently excluded from its habitat.
Fire exclusion thus became the policy for all reserves in which the noisy scrub-bird occurred.
My correspondent writes:
Dear Roger,
Reading your article regarding the ineffectiveness of water bombing in heavy fuels reminded me of a bushfire at Mt Manypeaks back in 2004. There was a lightning strike on the main ridge line near the top of the peaks on New Year’s Eve and a fire commenced, burning very slowly at first in the long unburnt fuels.
There was a bit of drizzle associated with the thunderstorm which had set the lightning strike, and light rain was forecast for the next few days. The vegetation in the uplands of the reserve is dense mallee eucalypts and woody shrubs with patches of open heath amongst extensive rock outcrops. The nearest road was 6km from the fire.
We assessed all the options for suppression. These were:
- walk in a team of fire fighters with rakes, shovels and knapsacks;
- walk in a bulldozer, accompanied by a fire crew;
- burn out the block containing the fire to the nearest roads/firebreaks; or
- attack the fire with water bombers.
The first two options were ruled out for safety reasons and sheer impracticality. The terrain was steep and rocky and neither ground crews nor bulldozers would be able to construct a break around the fire which could then be mopped up. The route to the fire would be through nearly impenetrable scrub, meaning that ground crews would have needed to slash a path to get to the fire. The ‘burning out’ option would increase the fire size to around 4000 hectares and require a large force of crews and equipment for several weeks because of the mix of fuel types and aspects on the mountain, and the variable fuel moisture conditions within the perimeter of a potential burn. Also the largest number of Noisy Scrub-birds (NSB) were known to exist within the a potential burn boundary. At that time it was thought that NSB could only survive in long-unburnt vegetation.
Hence water bombing was the selected strategy.
Two fixed wing water bombers were brought in and they commenced water drops on the fire. It was still a small fire when bombing operations commenced, about a half a hectare in size, and burning quietly, with flame heights of only half a metre to one metre.
We all expected that this small, mild fire would be rapidly extinguished. The water drops were being delivered at about 20 minute intervals. The conditions for accurate repeated drops were ideal. Indeed the fire edge was knocked down with each drop. However, after only a few minutes, the fire would again pick up, so that in between each drop, the fire would be back to where it was before the drop.
The trouble was, the water did not penetrate sufficiently down into the deep, dry layers of ground fuels and so could not prevent the fire edge reigniting. This was the case even where interception by tree canopy was not a factor.
The two water bombers worked all day, making 30 or 40 drops, but without success. When night fell, we still had an uncontained fire burning in the Mt Manypeaks reserve.
With the expense and frustration mounting, we re-assessed our options. Only one remained: this was to burn the whole area out under favourable conditions, over the course of the next couple of weeks. It was either this or wait until the fire burst out to the edge, which it might do under adverse conditions, and nobody wanted that. So, the fire bomber was called in to replace the water bomber, and after several missions dropping incendiary capsules over the next week or so, targeting the different fuel types and aspects, a “burn-out” was achieved. The results exceeded our expectations – a mosaic of burnt and unburnt (about 70% burnt) and a deep safe edge. The eventual size of the fire-treated block was about 4,500 ha.
There is a fascinating postscript to this story. Concerned about the Noisy Scrub Birds, the Government provided a special grant of $20,000 to monitor their populations and to carry out reintroductions, if necessary. But it turned out that large areas of long-unburnt fuels were not required to maintain NSB populations after all. The birds thrived in the mosaic of burnt and unburnt vegetation and five years after the burn, NSB populations had actually expanded from the pre-burn situation.
I enjoyed this letter. Not only did it confirm my view that in most situations water bombing unsupported by ground crews is basically ineffective in controlling a bushfire, it demonstrated yet again the resilience of our native species to mild-intensity fire that leaves a mosaic of burnt and unburnt country. I understand that subsequent research has shown that the main threat to the noisy scrub-bird is a combination of high-intensity all-consuming wildfire and feral predators such as the European fox and the feral cat. The future of this species is now known to depend on preventing whole-of-landscape wildfires by prescribed burning under mild conditions, accompanied by fox and cat control.
Case studies like this, providing actual experience from the real world of bushfire and land management as distinct from the fantasy world of the urban environmentalist, are never heard by the general public. Until they are, we will continue to see multi-millions of dollars invested in ever more and ever larger water bombers, always at the expense of sensible bushfire prevention and intelligent land and wildlife management on the ground.
As I have said on other occasions, I understand the value of water bombers, but it is restricted. They can assist ground crews on small fires, protect houses from a grass fire, or (in some situations) hold a fire in a remote area until ground crews arrive. But they cannot operate at night or under high winds, and are ineffective in the control of high-intensity forest fires. It is a flawed concept that water bombers can replace firefighters, or that they can provide a substitute for responsible preparation of potential fire grounds, especially fuel reduction burning. To advocate spending millions of dollars on water bombers at the expense of fuel reduction is to advocate wasting money, and will set up our communities and forests for ever-more damaging bushfires.
January 2016