Surface Fuels
Fire behavior fuel models that contain the parameters required to calculate fire behavior outputs.
Surface fuels, or fire behavior fuel models as they are technically referred to, contain the parameters needed by the Rothermel (1972) surface fire spread model to compute surface fire behavior characteristics, e.g. rate of spread, flame length, fireline intensity, and other fire behavior metrics. As the name might suggest, surface fuels account only for surface fire potential. Canopy fire potential is computed through a separate but linked process. The CO-WRA accounts for both surface and canopy fire potential in the fire behavior outputs.
An up-to-date surface fuel dataset at 20-meter (m) resolution was developed for this project, based on Scott and Burgan (2005) fuel models, enhanced with custom fuels created by Technosylva. The custom fuels distinguish this assessment from previous ones performed in Colorado as they allow a better characterization of fire behavior across the landscape. Additionally, the urban and road custom fuel models included in the assessment are key for better characterizing the exposure, vulnerability and risk of both buildings and population in the Wildland Urban Interface (WUI). This also allows for better modeling of fire encroachment in urban areas considering the building density, community structure and fuels surrounding the buildings and urban areas.
The following custom fuels were included in order to improve the fire modeling in timber, WUI and agricultural areas:
Timber: 2 new categories (171 and 191)
Urban: 7 new categories (911,912,913,914,915,916 and 919)
Roads: 5 new categories (941,942,943,944 and 949)
Agriculture: 4 new categories (931,932,938a and 939)
Water: 3 new categories (981,982 and 989)
Additionally, we also considered canopy fuel data to better simulate crown fire behavior. This includes:
canopy bulk density (CBD)
canopy base height (CBH)
canopy cover (CC)
canopy height (CH)
The updated fuel dataset also considered the effects of natural disturbances on vegetation (fires, insect and disease, and harvesting/fuel treatments) that occurred in Colorado from 2013 to 2022. More information about the methods used can be found in the Colorado 2022 Fuels Mapping Final Report.
Table 13 provides a description of the 2022 CO-WRA fuels dataset classes.
Table 13. 2022 Colorado 2022 Fuel Model Dataset classes
References
[26] CSFS 2022 Fuels Mapping Final Report. Technosylva, June 2022. Available from the Colorado State Forest Service.
2 NCEP Reanalysis data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their web site at https://www.esrl.noaa.gov/psd/