Fig 1.
The fire propagation probabilities are computed using a Cellular Automata model; these constitute the elements of the adjacency matrix of the lattice. Then centrality measures such as the Betweenness Centrality, Closeness and Bonacich centrality can be implemented to find the nodes (patches of land) which contribute more to the spread of the fire. (With black color is depicted an empty cell (containing no fuel). For the particular adjacency matrix shown, the most “infuental” node for the spread of the fire is the cell (node) 5.)
Fig 2.
A stereoscopic image of Rhodes island, Greece (acquired from the NASA Earth Observatory (public domain): http://earthobservatory.nasa.gov/).
Fig 3.
Map of the vegetation density of the area under study in Rhodes island, Greece as was before the wildfire incident of July 2008.
Table 1.
Parameter values for the CA model.
Fig 4.
The “expected” map of relative burning frequencies for the case of Rhodes island, Greece.
This was constructed using the CA model over 100 simulations all starting from the ignition point of the real incident of 22.07.2008 (Ag. Isidoros: Latitude: 36.15, Longitude: 27.85); the outline of the burned area of the real incident is also shown.
Fig 5.
The simple case of an ensemble of artificial forests.
Hazard intensity R(df) as obtained using the Bonacich (with β = 0.2, 0.5, 0.8), BC, Eigencentrality and the random distribution of fire breaks. The shaded area marks statistically significant differences between Bonacich and BC vs. random distributions as computed by the t-test (at a = 0.05).
Fig 6.
The case of Rhodes island, Greece.
Hazard intensity R(df) using the proposed (circles) and conventional (squares) distribution of fire breaks, as computed over nr = 3,200 simulations starting from equally-numbered ignition points. 90% percentiles are also illustrated with dotted bars. Statistically significant differences between distributions as computed by the t-test (at a = 0.05) arose for all values of df > 0.