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* Metric Name: Damage Potential  

* Tier: 1  

* Data Vintage: 08/2023. Includes disturbances through the end of 2022.  

* Unit Of Measure: Relative index, low to high  

* Metric Definition and Relevance: This metric, Damage Potential (DP), was developed by Pyrologix LLC. The composite Damage Potential (DP) dataset represents a relative measure of wildfire’s potential to damage a home or other structure if one were present at a given pixel, and if a wildfire were to occur (conditional exposure). It is a function of ember load to a given pixel, and fire intensity at that pixel, and considers the generalized consequences to a home from fires of a given intensity (flame length). This index does not incorporate a measure of annual wildfire likelihood.  

* Creation Method: DP values were binned based on the following ranges into 6 classes and assigned class names. 

0\. (None): Values = 0

1\. (Very Low): Values 0.01 to 20

2\. (Low): Values 20 to 35

3\. (Moderate): Values 35 to 50

4\. (High): Values 50 to 80

5\. (Very High): Values 80+

Damage Potential (DP) data was produced by Pyrologix LLC, a wildfire threat
assessment research firm, as part of a spatial wildfire hazard assessment
across all land ownerships for the state of California. The ongoing work
generally follows the framework outlined in Scott and Thompson (2013), with
custom methods and significant improvements developed by Pyrologix. The
project generally consists of three components: fuelscape calibration and
updates, wildfire hazard assessment, and risk assessment. It utilizes a
combination of wildfire models and custom tools, including WildEST (Wildfire
Exposure Simulation Tool), a custom modeling tool developed by Pyrologix
(Scott, 2020). To date, this work has resulted in a wide variety of spatial
data layers related to wildfire hazard and risk, including Damage Potential
(DP), representing conditions prior to the 2020, 2021 and 2022 fire seasons.
Work to date has been funded by the USDA Forest Service Region 5, the
California Energy Commission, and the USDI Bureau of Land Management with data
contributions from CAL FIRE. Please reference the Pyrologix 2021 project
report (Volger et al., 2021) for more information about the project or WildEST
analysis.

Damage Potential (DP) is a proprietary index developed by Pyrologix LLC
representing wildfire’s potential to damage a home or other structure if a
wildfire were to occur (conditional exposure). It is a function of ember load
to a given pixel and fire intensity at that pixel, and it considers the
generalized consequences to a home from fires of a given intensity (flame
length). DP is calculated based on two other datasets developed by Pyrologix:
conditional risk to potential structures (cRPS) and conditional ember load
index (cELI).

cRPS represents the potential consequences of fire to a home at a given
location if a fire occurs there and if a home were located there. It is a
measure that integrates wildfire intensity with generalized consequences to a
home on every pixel. Wildfire intensity (flame length) is calculated using
Pyrologix’ WildEST tool. WildEST is a scripted geospatial process used to
perform multiple deterministic simulations under a range of weather types
(wind speed, wind direction, fuel moisture content). Rather than weighting
results solely according to the temporal relative frequencies of the weather
scenarios, the WildEST process integrates results by weighting them according
to their weather type probabilities (WTP), which appropriately weights high-
spread conditions into the calculations. For fire-effects calculations,
WildEST generates flame-length probability rasters that incorporate non-
heading spread directions, for which fire intensity is considerably lower than
at the head of the fire.

The response function characterizing potential consequences to an exposed
structure is applied to fire effects flame lengths from WildEST for all
burnable fuel types on the landscape regardless of whether an actual structure
is present or not. The response function does not consider building materials
of structures and is meant as a measure of the effect of fire intensity on
structure exposure. The response function is provided below:

  * Flame length probability of 0-2 ft: -25
  * Flame length probability of 2-4 ft: -40
  * Flame length probability of 4-6 ft: -55
  * Flame length probability of 6-8 ft: -70
  * Flame length probability of 8-12 ft: -85
  * Flame length probability of >12 ft: -100

These results were calculated using 30m fire-effects flame-length
probabilities from the WildEST wildfire behavior results and then further
smoothed.

cELI is also calculated in WildEST, and represents the relative ember load per
pixel, given that a fire occurs, based on surface and canopy fuel
characteristics, climate, and topography within the pixel. Units are the
relative number of embers. cELI is based on heading-only fire behavior.

Damage Potential is then calculated as the arithmetic mean of cELI and cRPS
for each pixel across the landscape.

𝐷𝑃 = 𝑐𝑅𝑃𝑆 + 𝑐𝐸𝐿𝐼/2

Although flame length and its potential impact to structures is a function of
the fire environment at the subject location only, ember load is a function of
ember production and transport in the area surrounding the subject location. A
location with light fuel (and therefore low flame length) could still have
significant Damage Potential if surrounded by a fire environment that produces
copious embers.

  

* Credits: * Pyrologix, LLC