Abstract

Fuel moisture is a contributing factor to fire hazard, fire behavior, and fire effects. The spatial pattern of fuel moisture is also important, as it may influence fire spread and patterns of fire regimes. Fuel moisture models are used for management and research purposes, but we know of no study that scrutinizes the spatial patterns and response of these modeling approaches. We combined and modified two models of fuel moisture and examined the spatial structure of results it produced in a watershed with complex topography. Our model is largely based on dead fuel equations from the National Fire Danger Rating System, but includes a surface energy balance equation that allows solar radiation to modify boundary conditions. We examined the sensitivity of spatial structure to ambient humidity and an important model parameter. Results from our model indicate that sunny humid days lead to more spatial variation and structure in fuel moisture compared to sunny low-humidity days. Patterns were very sensitive to values of the convective heat transfer coefficient, implying substantial error if improperly parameterized. Our approach to modeling spatial heterogeneity in fire hazard dovetails with other research suggesting extreme weather increases the connectivity of landscapes with respect to fire, but also suggests models require careful parameterization.