Estimation of live fuel moisture content from MODIS images for fire risk assessment

This paper presents a method to estimate fuel moisture content (FMC) of Mediterranean vegetation species from satellite images in the context of fire risk assessment. The relationship between satellite images and field collected FMC data was based on two methodologies: empirical relations and statistical models based on simulated reflectances derived from radiative transfer models (RTM). Both models were applied to the same validation data set to compare their performance. FMC of grassland and shrublands were estimated using a 5-year time series (2001–2005) of Terra moderate resolution imaging spectroradiometer (MODIS) images. The simulated reflectances were based on the leaf level PROSPECT coupled with the canopy level SAILH RTM. The simulated spectra were generated for grasslands and shrublands according to their biophysical parameters traits and FMC range. Both models, empirical and statistical models based on RTM, offered similar accuracy with better determination coefficients for grasslands (r2 = 0.907, and 0.894, respectively) than for shrublands (r2 = 0.732 and 0.842, respectively). Although it is still necessary to test these equations in other areas with analogous types of vegetation, preliminary tests indicate that the adjustments based on simulated data offer similar results, but with greater robustness, than the empirical approach.