Western Wildfire Risk Explorer Technical Description
Introduction
The Western Wildfire Risk Explorer (WWRE) is an online interactive map built using open source
components. This application summarizes on a subwatershed level within national forest boundaries,
the burn probability, conditional flame length, and flame length probability for each of 6 flame length
classes.
The mean burn probability, conditional flame length, and flame length class probabilities were
calculated for each subwatershed within the national forests. A separate report for each national forest
in the west displays these values in graphical format. When the user selects the national forest from a
dropdown list, the map will zoom to the extent of the national forest.
The application software extends the Open Source Cloud Map mapping system developed by WWETAC.
I technical description of this software is available here.
The WWRE user interface is a web browser application built using open source components such as Ext
JS, GeoExt, and OpenLayers. All layers come from web map services delivered using GeoServer. The
application and GeoServer are deployed on an Amazon Web Services EC2 virtual server.
Figure 1. The web mapping system has GeoServer deployed on an Amazon EC2 server and
OpenLayers in a browser.
User Interface
Above the map is a dropdown list of 82 national forests in the west. The map automatically zooms to the
selected national forest. The 'Subwatershed Report' link to the right of the dropdown list will open a
report for the selected national forest. This report provides a table and charts to depict mean burn
probability, conditional flame length, and flame length class probabilities by watershed. The calculated
values use subwatershed boundaries clipped to the national forest.
The remaining user interface components are derived from the Open Source Cloud Map described here.
The following screenshots show the major components of the mapping system.
Figure 2. Burn probability for Mt. Hood National Forest. The legend is displayed to the
left of the map.
Figure 3. Mt. Hood National Forest with subwatersheds clipped to the forest boundary.
The complete list of layers available is displayed to the left of the map.
Figure 4. Mt. Hood National Forest subwatershed report. Map layer values are
summarized by subwatersheds clipped to the forest boundary.
Figure 5. Mt. Hood National Forest subwatershed report. Mean burn probability by
subwatershed.
Analysis Methods
The subwatershed summary report data was calculated by running the ArcGIS “Zonal Statistics” function
using the subwatershed layer with each of the following layers: Burn Probability (percent), Conditional
Flame Length (feet), Flame Length Class 1 (0 – 2 ft), Flame Length Class 2 (2 – 4 ft), Flame Length Class 3
(4 – 6 ft), Flame Length Class 4 (6 – 8 ft), Flame Length Class 5 (8 – 12 ft), Flame Length Class 6 (12+ ft),
Flame Length Class 5 and 6 (8+ ft). The subwatershed layer was clipped to the national forest
boundaries in order to provide summary data for areas only within the forest boundary.
Primary Layers
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National Forest Boundaries - Boundaries for 82 western National Forests. Above the map is a
dropdown list to select the forest and zoom to the forest extent. A subwatershed report link to
the right of the dropdown list will display a report for the selected forest.
Subwatersheds - Subwatershed boundaries clipped to the national forest boundaries. The
subwatershed report summarizes map data for the clipped areas.
Protected Areas - Protected areas are cornerstones of national and international conservation
strategies. By way of these designations, lands and waters are set-aside in-perpetuity to
preserve functioning natural ecosystems, act as refuges for species, and maintain ecological
processes. Complementary conservation strategies preserve land for the sustainable use of
natural resources, or for the protection of significant geologic and cultural features or open
space. PAD-US 1.1 (CBI Edition) attempts to include all available spatial data on these places. It is
our goal to publish the most comprehensive geospatial data set of U. S. protected areas to date.
PAD-US 1.1 (CBI Edition) is limited to the continental U.S., Alaska, and Hawaii. It does not include
protected areas data for U.S. territories at this time. The PAD-US 1.1 (CBI Edition) data set
portrays the nation's protected areas with a standardized spatial geometry and numerous
valuable attributes on land ownership, management designations, and conservation status
(using national GAP and international IUCN coding systems). The PAD-US 1.1 (CBI Edition)
defines protected area to include all lands dedicated to the preservation of biology diversity and
to other natural, recreation and cultural uses, and managed for these purposes through legal or
other effective means (adapted from IUCN definition). The database represents the full range of
conservation designations that preserve these natural resources in the United States. Our
database does not distinguish a protection threshold above which biodiversity is considered
secure. Instead, a complete suite of protected area attributes are provided for each polygon
with the purpose of giving users the information they need to define the most relevant
conservation thresholds for their own objectives and requirements. Collaborating with the
nation's leading data providers, the goal is to provide an annual update.
Burn Probability (percent) - Each cell in this 270m raster dataset contains the annual probability
that it will burn at any intensity. The dataset was produced using the Large Fire Simulator (FSim)
which was developed by Mark Finney at the USDA Forest Service Missoula Fire Lab
(http://www.firelab.org/) and was used for modeling fire risk in Wildfire Risk and Hazard:
Procedures for the First Approximation (Calkin, et al. 2010). The map contains a version of this
layer that is clipped to the National Forest boundaries and another that is unclipped.
Conditional Flame Length (feet) - Each cell in this 270m raster dataset contains the probable fire
intensity (expressed as flame length) if the cell should burn. This dataset was produced from
outputs from the Large Fire Simulator (FSim) which was developed by Mark Finney at the USDA
Forest Service Missoula Fire Lab (http://www.firelab.org/) and was used for modeling fire risk in
Wildfire Risk and Hazard: Procedures for the First Approximation (Calkin, et al. 2010). FSim
produces burn probabilities for six flame length classes. Summing the product of these burn
probabilities and their respective flame length class midpoints equals the Conditional Flame
Length (CFL) for the pixel. If the pixel burns, it most likely will burn at this intensity (flame
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length). The map contains a version of this layer that is clipped to the National Forest
boundaries and another that is unclipped.
Flame Length Class 1 (0 – 2 ft) - Each cell in this 270m raster dataset contains the probability
that flame length will be 0 - 2 ft if it burns. The dataset was produced using the Large Fire
Simulator (FSim) which was developed by Mark Finney at the USDA Forest Service Missoula Fire
Lab (http://www.firelab.org/) and was used for modeling fire risk in Wildfire Risk and Hazard:
Procedures for the First Approximation (Calkin, et al. 2010). The map contains a version of this
layer that is clipped to the National Forest boundaries and another that is unclipped.
Flame Length Class 2 (2 – 4 ft) - Each cell in this 270m raster dataset contains the probability
that flame length will be 2 - 4 ft if it burns. The dataset was produced using the Large Fire
Simulator (FSim) which was developed by Mark Finney at the USDA Forest Service Missoula Fire
Lab (http://www.firelab.org/) and was used for modeling fire risk in Wildfire Risk and Hazard:
Procedures for the First Approximation (Calkin, et al. 2010). The map contains a version of this
layer that is clipped to the National Forest boundaries and another that is unclipped.
Flame Length Class 3 (4 – 6 ft) - Each cell in this 270m raster dataset contains the probability
that flame length will be 4 - 6 ft if it burns. The map contains a version of this layer that is
clipped to the National Forest boundaries and another that is unclipped.
Flame Length Class 4 (6 – 8 ft) - Each cell in this 270m raster dataset contains the probability
that flame length will be 6 - 8 ft if it burns. The map contains a version of this layer that is
clipped to the National Forest boundaries and another that is unclipped.
Flame Length Class 5 (8 – 12 ft) - Each cell in this 270m raster dataset contains the probability
that flame length will be 8 - 12 ft if it burns. The map contains a version of this layer that is
clipped to the National Forest boundaries and another that is unclipped.
Flame Length Class 6 (12+ ft) - Each cell in this 270m raster dataset contains the probability that
flame length will be greater than 12 ft if it burns. The map contains a version of this layer that is
clipped to the National Forest boundaries and another that is unclipped.
Flame Length Class 5 and 6 (8+ ft) - Each cell in this 270m raster dataset contains the probability
that flame length will be greater than 8 ft if it burns. The map contains a version of this layer
that is clipped to the National Forest boundaries and another that is unclipped.