Simple indiceS for aSSeSSing fuel moiSture content and fire danger rating

BacKground A number of fire danger rating systems, which integrate selected quantifiable factors contributing to fire danger, have been developed to provide numerical indices relating to fire protection needs. it is important to note that fire danger indices have no real physical manifestation – they are just indices. Calculation of fire danger indices generally rely on information relating to the moisture content of fuels, fire weather and drought effects. in southeastern Australia, fire danger is assessed with reference to the McArthur Mark 5 forest fire danger index (FFDI), or the (modified) Mark 4 Grassland fire danger index (GFDI). These indices are typically implemented with circular slide rules or via their equivalent mathematical formulations. McArthur (1967) also provided tables for estimating the moisture content m of eucalypt litter as a function of temperature and relative humidity. McArthur’s tabular relationship was translated into a mathematical equation by Viney (1991). Matthews (2009) subsequently showed that the Mark 5 forest fire danger index could be equivalently formulated in terms of the fuel moisture content of eucalypt litter, as modelled by Viney.