Western Wildlands Environmental Threat Assessment Center

Wildfire Risk Analysis and Fuel Treatment Planning

Alan Ager, Western Wildlands Environmental Threat Assessment Center, Prineville Oregon, OR USA

Mark Finney, Rocky Mountain Research Station, Missoula MT John Anderson, BalanceTech Inc., Missoula, MT

Helen Maffei, Deschutes National Forest, Bend, OR

Western Wildlands Environmental Threat Assessment Center

The Problem• Landscape fuel treatment planning is a

complex process– Multiple scales– Multiple models– Data and model integration is weak– Wildfire occurrence is highly stochastic – we cannot

predict future wildfire likelihood with any certainty– We don’t have a well established analysis process

and performance metrics

Western Wildlands Environmental Threat Assessment Center

Risk analysis as a framework for fuel treatment planning

Simple case, only consider losses:Expected Loss = probability of event * loss

For multiple loss events of different intensities and probabilities

Expected loss = Σ (probability j * lossj)

Consider both benefits and losses of multiple events (also present and future)

Expected Net Value Change = (probability j * net value changej)

Definition of Risk:

Western Wildlands Environmental Threat Assessment Center

020000400006000080000

100000120000140000160000180000200000

<1 1 - 100 100 - 1000 >1000

Fire Size (acres)

Are

a B

urn

ed (

acre

s)

0

500

1000

1500

2000

2500

3000

3500

4000

4500

<1 1 - 100 100 - 1000 >1000

Fire Size (acres)

Nu

mb

er o

f F

ires

Umatilla National Forest Fire History

1970 - 2005

The majority of acres burned are from a few large fires that escape initial attack and spread over long

distances

Wildfire probability is

largely a function of

wildfire spread

Western Wildlands Environmental Threat Assessment Center

Loss Functions are required to link fire intensity with loss

-100

-50

0

50

100

0 5 10 15

Flame Length

Net v

alue c

hang

e (%

)

Western Wildlands Environmental Threat Assessment Center

Mitigate Risk by:

• Reducing wildfire probability

• Reducing fire intensity

• Change the loss function

Western Wildlands Environmental Threat Assessment Center

Wildfire Risk Analysis Process for Fuels Planning

• Design stand fuel treatments (FVS, FFE, SVS)• Design landscape treatment package (ArcGIS)• Simulate treatments (PPE) and generate FlamMap

landscape files• Calculate Burn probabilities by simulating lots of

wildfires (FlamMap)• Calculate loss functions (FVS-FFE)• Calculate expected loss (Access queries)• Compare treatment alternatives

Western Wildlands Environmental Threat Assessment Center

Emily Ager

Five Buttes

Oregon

Case Studies

Western Wildlands Environmental Threat Assessment Center

Five Buttes Study Area, Deschutes National Forest

Western Wildlands Environmental Threat Assessment Center

Burn Probability - No treatments, 2000 wildfires, 24 hour burn periods

0.001 - 0.005

0.005 - 0.010

0.010 - 0.015

0.015 - 0.020

0.020 - 0.025

0.025 - 0.030

0.030 - 0.035

0.035 - 0.040

0.040 - 0.045

> 0.045

Western Wildlands Environmental Threat Assessment Center

17,000 acre fires

Size of fires generated from random ignitions

2500 acre fires

Western Wildlands Environmental Threat Assessment Center

Stands selected for fuel treatment, 20% of landscape treated

Owl habitat stands

treatments

Western Wildlands Environmental Threat Assessment Center

0% treatment 10% treatment

20% treatment 50% treatment

Western Wildlands Environmental Threat Assessment Center

Burn probability does not indicate loss

• Need to calculate expected loss, the probability of a fire and loss of habitat

Western Wildlands Environmental Threat Assessment Center

0

50

100

150

200

250

300

350

400

1 2 3 4 5 6 7 8 9 10

Flame Length

Out of 1000 simulated fires on pixel X,Y, how many eliminate owl habitat?

Lethal flame length~100 fires have flame lengths that exceed the lethal flame length

Expected loss = 100/10000 = 0.01

Western Wildlands Environmental Threat Assessment Center

Calculate the lethal flame length for owl habitat stands• Simulated fire in each stand

with flame lengths ranging from 0.5 - 15 meters, 0.5 meter increments [FLAMEADJ]

• Determine the flame length when the stand at no longer meets habitat requirements

• Query these results against the FlamMap output table

Western Wildlands Environmental Threat Assessment Center

Western Wildlands Environmental Threat Assessment Center

Expected Loss of Spotted Owl Habitat for 6 Treatment Intensities

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50 60

Percent of Landscape Treated

Exp

ecte

d Lo

ss (%

of m

ax)

max

Western Wildlands Environmental Threat Assessment Center

Summary: Risk Analysis in Fuel Treatment Planning

• Provides a quantitative measure of fuel treatment performance

• Accounts for fire spread, intensity, and loss

• Can incorporate multiple future and present losses and benefits

Western Wildlands Environmental Threat Assessment Center

The WO-SPOT and R5 Fireshed

Assessment Process

Quantitative Framework for Wildfire Risk

WWETAC, JFSP 06-1-04-06 (Miller, Ager, Finney,

Parisien)

ArcFuels

FVS, FFE, PPE FlamMap, Behave, FOFEM, Nexus,

Western Wildlands Environmental Threat Assessment Center

ArcFuels

• VBA macros in ArcMap• Implemented on 2 toolbars• ArcObjects library allows full GIS functionality• Distributed in an .MXD project file • Macro errors do not crash ArcMap• Hooks to Excell, Access, FVS, FlamMap,

Farsite, Nexus, SVS, Behave• Interface