Numerical Investigation of Slope and Elevation Effects on Smoldering Peat Fires

Smoldering peat fires are a persistent, low-visibility form of wildfire that contribute significantly to environmental degradation, including transboundary haze pollution and long-term carbon emissions. Understanding their propagation under varying landscape and climatic conditions is crucial for improving wildfire risk assessment and ecosystem resilience. This study investigates how terrain slope and elevation, two critical but underexplored environmental factors, affect the spread dynamics of peat smoldering. A two-dimensional numerical model was developed in COMSOL, incorporating a validated five-step reaction mechanism to simulate coupled chemical and physical processes. The model was benchmarked against experimental data and used to assess smoldering behavior under various slope angles (0°-30°) and elevations (0–5000 m). Results show that slope effects are direction-dependent: uphill smoldering is intensified by buoyancy-enhanced oxygen supply, increasing horizontal spread by 53% at a 30° slope. Conversely, downhill smoldering is suppressed by opposing gas flow and shows limited slope sensitivity. Elevation has a dampening effect on smoldering intensity: as altitude increases from 0 to 5000 m, decreasing atmospheric pressure and oxygen availability lead to an approximately 30% reduction in the horizontal spread rate, together with a linear decrease in peak temperature. These findings provide new insights into the environmental drivers of smoldering peat fires and offer scientific support for wildfire prediction and control strategies, particularly in mountainous and high-elevation regions.