Scion’s Fire team, together with the University of Canterbury, successfully conducted a number of experimental burns over the past two weeks in crop stubble vegetation. The burns build on the data collected in similar fuels back in March 2018.
The burns were the contingency for the next planned phase of experiments to test the new convective fire spread theory. It had been hoped to conduct a series of gorse burns this Feb/Mar. However, factors conspired to prevent this, with land use consent requirements delaying the planned gorse experiments, the US Govt shutdown meaning the US Forest Service team couldn’t travel, and then a total fire ban causing the stubble burns to be delayed by almost a month!
Four experimental burns were carried out to test improved data collection methods, including determining fire rate of spread from aerial UAV video using georeferenced ground targets. Hot targets were also used to aid quantification of aerial infrared measurements of flame and surface temperatures. Turbulence before, during and after the flame front spread past a 10m tower was also measured using paired sonic anemometers, rather than the single anemometer used at each height last time. It is hoped these paired sonic measurements will aid in quantifying the scale of the turbulent eddies generated by the flame front.
Four additional point-line ignition comparison burns were also conducted to investigate fire acceleration and development patterns. Spread of fires from point ignitions, and short (10 m) ignition lines, were compared against longer (up to 50 m) line ignitions lit simultaneously under the same burning conditions. Here the aim is to better understand the relative rates and duration of acceleration of different sized fires which, despite the long history of fire research, is still poorly understood.
All going to plan, the team plans to carry out the next phase of burn experiments in gorse shrub fuels later in the year (Oct/Nov.).