Modelling the Drying of Heterogeneous Vegetation under Bushfire Conditions: A Review of Physics-Based Modelling Approaches

Bushfires represent one of the most severe hazards driven by climate change, significantly impacting environmental ecosystems, human health, and society. The spread and intensity of bushfires are closely linked to the moisture content and dynamics of vegetation, which influence processes such as pyrolysis, ignition, combustion, and, ultimately, fire propagation. Therefore, accurately predicting moisture dynamics is crucial for forecasting fire behaviour and spread, which directly affects environmental risk management. Currently, empirical models are commonly used for this purpose; however, they often oversimplify the complex heat and mass transfer processes involved in vegetation drying. In contrast, physics-based models offer a mechanistic framework that accounts for vegetation structure, the water transport mechanisms within plants, and fire-induced environmental factors. This review discusses recent advancements in drying models, focusing particularly on physics-based approaches and their potential applications in bushfire scenarios. It proposes a conceptual framework that encompasses key aspects, including vegetation heterogeneity, moisture transport, coupled heat and mass transfer processes, and environmental factors. Additionally, the review highlights the main challenges in developing a comprehensive drying model, including model parameterisation, computational complexity, and the necessity for validation through experimental and field studies. Finally, it suggests future directions, emphasising that integrating multi-scale modelling approaches and machine learning techniques could enhance the applicability of drying models for environmental risk management and ecosystem assessments.