Modelling drying processes of fuelbeds of Scots pine needles with initial moisture content above the fibre saturation point by two-phase models
Sen Jin A B and Pengyu Chen A
+ Author Affiliations
- Author Affiliations
A College of Forestry, Northeast Forestry University, Harbin, Heilongjiang Province150040, PR China.
B Corresponding author. Email: jins-cf@nefu.edu.cn
International Journal of Wildland Fire 21(4) 418-427 https://doi.org/10.1071/WF10119
Submitted: 24 October 2010 Accepted: 14 October 2011 Published: 26 March 2012
Abstract
Modelling the drying process of fuel moisture with initial moisture content above the fibre saturation point can be used to determine when fuel will become sufficiently dry (after precipitation) to burn and provide a more accurate prediction of fire potential. Based on analysis of the mechanism by which the drying process occurs, we propose a model comprising two phases distinguished by a moisture threshold of 0.35 g g–1, the fibre saturation point; one phase is controlled by evaporation and the other by diffusion. Each phase has a distinct equation with a different timelag. We compared our two-phase model with a one-phase model (one-timelag model) and another two-phase model by estimating drying of 15 Scots pine (Pinus sylvestris var. mongolica) needle fuelbeds. The results indicate that the two-timelag model improves moisture modelling, thereby reducing mean absolute error by more than 30%, i.e. from 0.0047 g g–1 (one-phase model) to 0.0030 g g–1. The model yields consistent results, further suggesting its potential for improving fuel moisture prediction of fire danger rating systems. The first timelag of the model is affected by fuelbed properties. Equations based on variables that represent fuelbed properties were established, thus saving time when estimating parameters for stand-specific fuel moisture models.
Additional keywords: fuelbed properties, two-timelag model.
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