Fire Modeling and Risk PreventionOrinda, CA

Katie McKnight | Kirsten Jurich

• Mitigation Objectives

• Research Question

• Rationale

• Study Site

• Assumptions and Limitations

• Data Analysis & Results

• Findings

• Recommendations

TABLE OF CONTENTS

• Perform a high-resolution simulation of mitigation measures specific to the Sleepy Hollow region of Orinda

OBJECTIVES

• Results can be used to assess effectiveness of mitigation measures and inform concerned homeowners and future fire mitigation strategies

RESEARCH QUESTION

What impact would pine tree removal have on fire vulnerability for Sleepy Hollow homeowners?

Photo Source: disasterandemergencysurvival.com

• Tallest pine trees likely closer to death than shorter

pines

• Dead pines pose large fire risk to the community

• If pine trees on the verge of death were

removed, how would that change the fire

potential?

RATIONALE

BARK BEETLES

STUDY SITE

Grove of pines

• 24.7-acre study site chosen• DSM - DEM = nDSM • Query: 69 to 125 feet • Digitized unburnable vs. burnable zones and fuel types• Used street view in Google Earth to verify locations• About 1.4 acres of pine trees

Corner of Normandy Ln. and Sleepy Hollow Ln.

METHODOLOGY

600’

View from study site

Two scenarios analyzed in FlamMap:

1. Existing Condition (unchanged fuel model)

2. Pine Mitigation (fuel model changed from class 10 to 1 in pine locations)

METHODOLOGY

• Flame Length (feet)

• Crown Fire Activity (class)

• Heat per Unit Area (kJ/m2)

• Rate of Spread (chains/hr)

Variables measured:

• Spatial changes (ArcGIS)

• Histogram comparisons (Excel)

Data Analysis:

FUEL MODELS: land use type

Existing Condition Pine Mitigation

600’

FUEL MODELS: land use type

Existing Condition Pine Mitigation

600’

ASSUMPTIONS & LIMITATIONS

• Wind blowing uphill at 20 feet above surface at 35 mph

• Fuel moisture, aspect, elevation, slope and canopy cover inputs adapted from Claremont

Canyon dataset provided

• “Near-death” pines assumed to be within 69’ - 125’ height range

• Verifications of pines made through Google Earth Pro street view

CROWN FIRE ACTIVITY: class

Existing Condition Pine Mitigation

600’

• Assessment of changes in crown fire activity (CFA) over entire study area

• 2 %, or 0.5 acres, of total study area shifted from active crown fire (class 3) to surface fire (class 1)

HEAT PER UNIT AREA: kJ/m2

Existing Condition Pine Mitigation

600’

• Assessment of changes in heat per unit area (HUA) over entire study area

• Of the area affected by mitigation, largest reduction in HPU between -15,000 to -20,000 kJ/m2 (-48%)

• Second largest reduction in HPU between -60,000 to -65,000 kJ/m2 (-33%)

RATE OF SPREAD: chains per hour

Existing Condition Pine Mitigation

600’

• Changes likely due to shift in land use from tree canopy to grass (quicker burn)

• ROS between 70 to 80 chains per hour decreased by 38%, but increased by 10% between 30 to 40 c/hr

FLAME LENGTH: feet

Existing Condition Pine Mitigation

600’

• Assessment of changes in flame length over entire study area

• Reduction of: 60’ - 70’ flames over 0.4 acres 70’ - 80’ flames over 0.2 acres 80’ - 90’ flames over 0.1 acres 90’ - 100’ flames over 0.03 acres

• Increase in: 0’ - 10’ flames over 0.7 acres

• Tree removal of near-death pines can greatly reduce flame length, rate of spread, heat per

burned area and crown fire activity

• Effects of pine tree removal include:

FINDINGS

• shift in crown fire activity from active crown fire to surface fire

• overall reduction of heat per unit area by 47,000,000 kJ/m2

• overall decreases in high rates of spread at dangerous intervals (60 - 100 chains per

hour) to more manageable rates of spread (0 - 20 chains per hour)

• reduction from very large flame lengths (between 60 - 100 feet) to moderate flame

lengths (0 - 10 feet)

• Alert fire officials to potential bark-beetle related tree deaths

RECOMMENDATIONS

• Community outreach to train homeowners in identifying indicators of bark beetle

infestations

• Crowd-sourcing application to monitor affected areas

• Expedited permitting process for removal of infested pine trees