Firepower

It is bushfire season. As the temperature in Geelong and surrounding districts peaked at 41 degrees yesterday, a small grassfire broke out near the Barwon River outside of the township of Stonehaven. On this occasion, it was contained within a few hours. Despite media and government reports of an aerial firefighting unit, several tankers from Geelong and surrounding towns and the possible presence of smoke, there was nothing to be seen from a distance. None-the-less, the tanker from Gnawarre became bogged and then trapped in the flames. No-one was injured, however the truck suffered substantial damage.

Ten News footage of the Gnawarre tanker in flames at Stonehaven

The potential for danger was clearly quite real and it got me thinking  about what role fire has played along the banks of the Barwon over the centuries. Certainly, the local Wathaurong tribes are known to have conducted burns as part of the land management strategies they used to encourage the propagation of various food sources. Studies have suggested that the current growth of native trees in what is believed to be an untouched remnant of bushland at Ocean Grove - not far from the Lake Connewarre Game Reserve - may have changed over the last 150 years with the cessation of burning by the Wathaurong tribes.

Man-made lake and remnant bushland in the Ocean Grove Nature Reserve

At the other end, near the headwaters of the Barwon, it is rather a different story. The Otway Ranges receive more rainfall than any other part of the state. This has lead to the growth of temperate rainforest which does not burn easily - if at all. I am informed that prior to European arrival, a bushfire could be expected in some parts of the Otways no more regularly than every 300-500 years!
With the arrival of white settlement however, things have changed somewhat. Clearfell logging has had an impact on the ability of the area to withstand bushfire damage and both have had a significant effect on water catchment capacity and water quality. Clearfell logging in the Otways ceased in May, 2008. It is predicted that within 60 years if no further logging takes place that water yields will increase by 10%.
Over time, damaged areas of bushland will regenerate, however even this comes at a cost to short term water catchment capacity. Young trees draw water from the soil, evaporating it through their leaves as they respire and grow. Old growth trees by contrast retard the flow of runoff water through the soil which remains moist, allowing more time for it to drain into the creeks and rivers of the catchment area. Likewise, bushfire can not only damage old growth trees, but it draws moisture from the ground which would otherwise end up in the catchments.

Section of regrowth  and old growth forest at West Barwon Dam

The West Barwon catchment area is largely old growth forest however, parts of this were burnt out during bushfires in the area in 1919 and again in the 1939 Black Friday bushfires when Victoria's rivers were reported to be at their lowest levels for 80 years. One story tells of Bill Kellas, a survivor of the more recent 2009 Black Saturday Bushfires who as a six year old boy, spent two days sheltering beside the Barwon in 1939 with his mother. They survived the bushfires by ducking beneath the surface of the river to avoid falling embers and hiding beneath wet blankets.
Bushfire management has come a long way since then and not surprisingly, the threat of bushfire in the Otways and along the Barwon is very much a "hot topic". So much so in fact that the authorities responsible for developing safety strategies in the region (the Department of Sustainability and Energy and Parks Victoria) have won the Motorola Innovation Knowledge Agency Award for those deemed the most progressive in the fields of fire and emergency.
Let's hope their innovations are effective!