modeling fire behavior and assessing post fire burn ...and post-fire nbr values...
TRANSCRIPT
2007 SHRUG GIS Workshop
Modeling Fire Behavior and Assessing Post Fire Burn Severity for the 2007
Big Turnaround Fire Complex Joe Noble
Joshua Picotte
2007 SHRUG GIS Workshop
Project Overview
BackgroundProject QuestionsResultsConclusions
Mark Jamieson May 31, 2007
2007 SHRUG GIS Workshop
Background-Burn Severity and Joint Fires Science Program (JFSP)
Burn Severity-ecosystem change and landscape changeSystem developed in 1996 by Carl Key and Nate Benson Started in the Western United States
Initial Fires Assessed-1994 Glacier National Park FiresNeeds more work in East
JFSP was formed in 1998 to provide support for fuel and fire management programs
Key and Benson 1995
Key and Benson 1995
2007 SHRUG GIS Workshop
Background-Composite Burn Index (CBI) and Normalized Burn Ratio
(NBR)NBR-Remote sensing of burn severityLandsat R4 (NIR, Veg) and R7 (SWIR, Soil)
NBR = (R4-R7)/ (R4+R7)dNBR=NBR prefire-NBR postfire
CBI-Ground measure of burn severity30 m plot
CBI should validate NBR values
2007 SHRUG GIS Workshop
Background-deltaNormalized Burn Ratio (dNBR)
dNBR: Change in reflectance between pre-fire (1 year pre-fire) and post-fire NBR values
dNBR=NBRprefire-NBRpostfire
Weighted dNBR = Average of plot center and corners (N=5)
30m
30m
30m
659 - 1300High
439 - 659Moderate-High
269 - 439Low-Moderate
99 - 269Low
-100 - 99UnburneddNBRSeverity
2007 SHRUG GIS Workshop
Background-Composite Burn Index (CBI)
Burn Index: 0-30-Unburned3-Severe Burn
Five Strata4-5 Ratings FactorsAveraged
CBI ScoreAverage of Five Strata
2007 SHRUG GIS Workshop 0 20 4010 Kilometers
²
Background-Big Turnaround Fire Complex Burn Severity
UnburnedLowLow-ModerateModerate-HighHigh
Burn Severity
2007 SHRUG GIS Workshop
Background-Assessed Habitats Within the Big Turnaround Fire Complex
A. Flatwood Pineland• Palmetto• Long-Leaf/Slash Pine
B. Depression Swamp• Cypress• Titi• Pond Pine• Ilex sp.
A.
B.
2007 SHRUG GIS Workshop
Background-Plot Locations
_ Plot Locations
UnburnedLowLow-ModerateModerate-HighHigh
Burn Severity
0 7 143.5 Kilometers
²
Plots:
89 CBI
32 “Virtual”
2007 SHRUG GIS Workshop
Project Questions
1) Does this system adequately describe burn severity within ecosystems affected by the Big Turnaround Fire Complex?
2) Are there differences in the effectiveness of using CBI and dNBR to categorize burn severity in flatwood and depression swamp community types?
3) What are the appropriate dNBR breakpoints for a given burn severity categories?
2007 SHRUG GIS Workshop
Results-Correlations Between CBI and dNBRWithin Flatwoods
y = 0.0022x + 0.09R2 = 0.7493
0
0.5
1
1.5
2
2.5
3
-100 0 100 200 300 400 500 600 700 800 900 1000
dNBR
CB
I
2007 SHRUG GIS Workshop
Results-Correlations Between CBI and dNBRWithin Depression Swamps
y = 0.0016x + 0.691R2 = 0.5419
0
0.5
1
1.5
2
2.5
3
-200 0 200 400 600 800 1000 1200
dNBR
CB
I
2007 SHRUG GIS Workshop
Results-Flatwood Vs. Depression Swamp dNBR Breakpoints
660690974High
440496662Moderate-High
270303349Low-Moderate
10010937Low
<100<109<37Unburned
WesternAverageCalculatedSeverity
660690982High
440496755Moderate-High
270303527Low-Moderate
100109300Low
<100<109<300Unburned
WesternAverageCalculatedSeverity
2007 SHRUG GIS Workshop
Conclusions
dNBR images accurately represented the burn severity of the 2007 Big Turnaround Complex dNBR Breakpoints differed between vegetation typesdNBR Breakpoints calculated per vegetation type differ from suggested Western Breakpoint range of ± 100If possible, dNBR breakpoints should be calibrated with CBI plots for each fire
Increased accuracyMore research needs to be done
Effects of time since fireAccuracy of extended assessments
2007 SHRUG GIS Workshop
Acknowledgements
Dave BrownlieJason DrakeSue GraceJohn Bethay State ParkSusan KettShia MucciMatt Mueller Don OhlenOsceola National Forest Okefenokee National Wildlife RefugeKevin Robertson