Burning Index

Burning Index (BI) is a number used by the National Oceanic and Atmospheric Administration (NOAA) to describe the potential amount of effort needed to contain a single fire in a particular fuel type within a rating area. The National Fire Danger Rating System (NFDRS) uses a modified version of Bryam's equation for flame length – based on the Spread Component (SC) and the available energy (ERC) – to calculate flame length from which the Burning Index is computed.{{cite web | title=National Fire Danger Rating System: Indices | website=wrh.noaa.gov | date=2011-05-19 | url=http://www.wrh.noaa.gov/sew/fire/olm/nfdr_ind.htm | archive-url=https://web.archive.org/web/20110519200326/http://www.wrh.noaa.gov/sew/fire/olm/nfdr_ind.htm | archive-date=2011-05-19 | url-status=dead | access-date=2020-04-29}}

The equation for flame length is listed below:

::$F\_L=j\backslash left\; [\backslash left(\backslash frac\{SC\}\{60\}\backslash right)\; (25(ERC))\backslash right\; ]^\{0.46\}$

where:

:j is a scaling factor,

:SC is the spread component,

:and ERC is the Energy Release Component.

Consequently, the equation for the Burning Index is:

::$BI=j\_1\backslash \; F\_L$

where $j\_1$ is the Burning Index scaling factor of (10/ft). Therefore, dividing the Burning Index by 10 produces a reasonable estimate of the flame length at the head of a fire. A unique Burning Index (BI) table is required for each fuel model.