Mapping surface fine fuel moisture content

Moisture content of dead fine fuel plays a decisive role in determining fire ignition and spread, and it is also an important input variable for many fire danger rating systems. Consequently, mapping dead fuel moisture content (FMC) is crucial and necessary for bushfire management but is not yet regularly accessible and available at a continental scale for Australia.

This report builds upon the research carried out by the team of the BNHCRC project “Mapping Bushfire Hazard and Impact”. The earlier research involved developing new theory to couple vapour exchange and capillary flux from the soil to model litter fuel moisture content (FMC) and map dead fine FMC at 1h time steps and 5km spatial resolution for a pilot area in Victoria. In research reported here, soil moisture estimates were taken from the outputs of the BNHCRC project, "Mitigating the effects of severe fires, floods and heatwaves through the improvements of land dryness measures and forecasts", (also colloquially known as the JASMIN project, after the modelling framework developed within the project). The physics based Koba dead fine FMC model was used as the modelling framework. Results demonstrate the feasibility of mapping hourly dead fine FMC at 5 km resolution. The estimates of dead fine FMC were improved by our proposed coupled model, especially for subsurface litter where litter is in contact with the soil.

The methodology has the potential to be extended at a continental scale and delivered to stakeholders in a timely fashion via the Australian Flammability Monitoring System in future research. This information can help assist the development and improvement of a new national fire rating system and support Predictive services and Fire Behavior Analysts.