7th Workshop on Forest Fire Management - EARSeL, European ...

Fuel model mapping using ikonos imagery to support spatially explicit fire simulator 77
similar to CM2 and CM3 (respectively 22.2 and 25.50 Mg ha -1 ). Table 2
shows the accuracy coefficients as well as the omission and commission
errors, obtained from the supervised classification of IKONOS images. The
achieved overall accuracy was 72.73%, with a Kappa coefficient of 0.67.
The main source of error among all classes was due to the misclassification
of the ‘‘Broad-leaf” class (user’s accuracy of 37.50%); the 12% of its pixels
were classified as “High and close maquis”, due to the similar spectral characteristics
of leaves. Regarding to the maquis, the major classification
problems come from the high mixing between “Medium” and “Low and
open” maquis, and “Agriculture and pasture” fuel type. This was probably
due to both the limited spectral resolution of the sensor and the high spatial
resolution that increased the spectral within-field variability. The fuel
model maps derived from IKONOS images were imported into FARSITE.
Results from FARSITE simulations (Table 3) showed that both the average
rate of spread and the burned area values were affected by the different
resolutions of fuel model maps. In particular, the burned area was highly
sensitive to changes on fuel map resolution for moderate wind speed (from
45% to 66% of increase relatively to the 5m reference map) compared to
the rate of spread, that was more sensitive (from 30% to 32% of increase)
for low values of wind speed.
4 - Conclusions
Results showed that the use of remotely sensed data at high spatial resolution
achieves high values of accuracy. The sensitivity analysis showed
that changes in fuel map resolution affect the predictive capabilities of the
fire behaviour simulators. In conclusion, the analysis of IKONOS data represents
a valuable tool to obtain fuel model maps for spatially explicit modelling
applications.
References
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Finney, M.A., 2004. FARSITE: Fire Area Simulator-model development and
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ICONA, 1990. Clave fotografica para la identificación de modelos de combustible.
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