Size, Density and Land Cover datasets were all obtained from the Multi-source Land Cover dataset. This dataset was in ArcGIS raster format when downloaded from the Fire and Resource Assesment Program. It had to be converted to vector format and then from that shapefile size, density and land cover were rasterised. The new datasets were reprojected into UTM Zone 10 NAD 83. These new raster files were then converted into ASCII and imported into IDRISI.
In IDRISI, size was reclassified according to how conducive it was to the spread of fire and to allow FUZZY to be applied to it.
Land Cover was reclassified twice, firstly to create a Boolean constraint where water, wetlands and urban areas were reclassified 0 and everything else 1. Land Cover was then also ranked according to the flammability of the cover:
Reclassification of Size
Seedling 1 - 1
Sapling 2 - 2
Multi-layered 6 - 3
Pole 3 - 4
Small Tree 4 - 5
Medium/large 5 - 6
Reclassification of Land Cover
Urban 100 - 0
Water 90 - 0
Wetlands 80 - 0
Barren/Other 20 -1
Herbaceous 60 - 2
Agriculture 10 - 2
Hardwood Forest 51 - 3
Hardwood Woodland 52 - 4
Coniferous Forest 31 - 5
Coniferous Woodland 32 - 6
Shrub 70 - 7
Desert Woodland 42 - 8
Desert Shrub 41 - 9
Temperature and Precipitation.
These sets were obtained as ArcGIS shapefiles projected into UTM Zone 10 NAD 83. They were converted into raster format in ArcGIS and then the rasters were converted into the ASCII format to enable them to be imported into IDRISI.
All of the available literature on fire hazard used millimeters and Centigrade when discussing precipitation and temperatur. These datasets used inches and Fahrenheit therefore had to be converted to millimeters and Centigrade to enable analysis. The image calculator was used to produce new datasets in these measurements. To convert precipitation to milimeters the formula [precipitation]*25.4 was used. The formula ([temperature]-32)*(5/9) was used to convert temperature to Centigrade.
Contour data was obtained as an ArcGIS .e00 transfer file. This was imported into ArcGIS and converted to a shapefile. This was reprojected into UTM Zone 10 NAD 83 and then converted into raster format.
In IDRISI the operation INTERCON was used to convert the rasterised contour data into a Digital Elevation Model. FILTER operation was performed on the new DEM using the mean value and 3x3 to eliminate noise from the data. This produced a smoother looking image. The SLOPE and ASPECT operations were used to obtain slope and aspect from this DEM using a conversion factor of 0.3048 because the contour data was in feet rather than meters.
These were obtained as ArcGIS shapefiles. There was other data in these sets however only the year of the fire was needed therefore only this was converted to raster format. These were then converted to ASCII format and imported into IDRISI
When the data was converted to raster ArcGIS assigned a value to each year therefore new values had to be assigned to these to allow FUZZY to be applied according to how long it had been since the last fire occurred. The ASSIGN operation was used for this.
Multicriteria Evaluation of Wildfire Hazard in California
Data Acquisition Data Preparation and Analysis Multi-Criteria Evaluation and Results Discussion References