Environmental Science Fire Danger Index

Question: Describe about the Environmental Science for Fire Danger Index. Answer: 1. Which town in NSW has the greatest Fire Danger Index, and what is its value? Is the McArthur Forest Fire Danger Meter applicable in all circumstances? Why/why not? The results are as shown in the table below: Town Drought factor FDI Lismore 10 11 Grafton 1 1 Coffs Harbour 4 4 Taree 5 15 Scone 5 17 Nowra 7 61 Armidale 8 15 Walgett 10 41 Dubbo 8 13 Parkes 7 10 Tibooburra 10 29 Cobar 10 30 Hay 9 15 Therefore the town in NSW with the greatest FDI is Nowra, with a value of 61 (extreme). McArthur Forest Fire Danger Meter is not applicable in all circumstances because it has been designed to accept inputs within certain ranges only. For instance, it accepts temperatures from 0 to 100; humidity from 0 to 100%, wind speed from 0 to 100 km/h, fuel load from 0 to 50 tonnes/ha, and a drought factor of 0 to 10 (Barlings, P. (n.d.)). This means that if any of the inputs are outside the specified range, the value of FDI cannot be determined using McArthur Forest Fire Danger Meter. 2. What are the minimum and maximum spotting distances and rates of spread of the fire? By what mechanism(s) can fires travel faster? The results are as shown in the table below Fuel load (t.ha-1) Spotting distance (km) Flame height (m) Rate of spread (km.h-1) 1 0 0 0.1 4 0.04 0.24 0.39 8 0.41 2.48 0.78 12 0.75 4.72 1.17 16 1.07 6.96 1.57 25 1.7 12 2.45 Thus the minimum and maximum spotting distances are 0 km and 1.7 km respectively, while the minimum and maximum rates of fire spread are 0.1 km.h-1 and 1.17 km.h-1 respectively. Fires can travel faster when the: fuel loads present increase, weather is hotter and drier, wind is stronger, humidity is low, and slope along which the fire is spreading increases (ACT Emergency Services Agency, 2011). 3. Experiment with the importance of attendance and the other factors for the survival of houses. Which house in Table 3 has the greatest chance of survivability? Which has the least chance? To which factors is house survival most sensitive? The results are as shown in the table below House 1 House 2 House 3 House 4 Holiday house 1 Holiday house 2 House survival probability (%) 98 94 94 75 62 10 Thus the house with the greatest and least chance of survivability is House 1 (98%) and Holiday house 2 (10%) respectively. House survival is most sensitive to persons in attendance, roof wooded or not wooden; and roof tiled or has a pitch of 10 (design), presence of flammable objects nearby i.e. landscaping and vegetation, as discussed by Bishop, Handmer, Winarto, McCowan (2011) 4. Why does a fire burning uphill travel faster than one burning downhill? There are several reasons why a fire burning travels faster uphill than downhill. First, the fire travels or moves in the direction of the path or ambient of which, which in uphill. Second, the fire preheats the fuel present upwards, since the heat and smoke travels up the hill, thus making it easier for the fire to travel uphill faster. Lastly, when the fire is burning, hot air rises upwards thus accelerating the speed of fire uphill (Kirschenmann, 2012). References ACT Emergency Services Agency. (2011). What is a bushfire? Retrieved from https://esa.act.gov.au/community-information/bushfires/what-is-a-bushfire/ Barlings, P. (n.d.). Forest fire danger meter McArthur Mk5. Retrieved from https://www.cfa4wd.org/information/Forest_FDI.htm Kirschenmann Zach. (2012). Did you know? Forest fires move faster uphill. Retrieved from https://chspineneedle.com/2012/04/19/did-you-know-forest-fires-move-faster-uphill/ Bishop, I., Handmer, J., Winarto, A., McCowan, E. (2011). Survival in dangerous landscapes a game environment for increasing public preparedness. ResearchGate, pp.222-229.