Simple models for predicting dead fuel moisture in eucalyptus forests

Fire behaviour prediction requires models of dead fuel moisture that are both accurate and suitable for use for operational applications. The paper investigates two methods of developing a simple operational fine fuel moisture model from a more complex process-based model. The first simple model is a table of fuel moisture predictions for values of air temperature, relative humidity, wind speed and solar radiation. The second model reduces the original model to a single differential equation, which may be used on low-powered computers. The simple models are tested against the output of the original model and against observations from two case studies in dry eucalyptus forest in south-western Australia. The single differential equation model was capable of reproducing the prediction of the process-based model at all times of the day, with mean error (ME) in predictions of –0.1% and mean absolute error (MAE) of 0.6%. The table model performed less well, with ME = –0.7% and MAE = 1.1% at 1500 hours, and ME = –1.2% and MAE = 3.0% at other times of the day.