Fire Modeling and Risk Prevention Orinda, CA. Katie McKnight Kirsten Jurich

Transcription

1 Fire Modeling and Risk Prevention Orinda, CA Katie McKnight Kirsten Jurich

2 TABLE OF CONTENTS Mitigation Objectives Research Question Rationale Study Site Assumptions and Limitations Data Analysis & Results Findings Recommendations

3 OBJECTIVES Perform a high-resolution simulation of mitigation measures specific to the Sleepy Hollow region of Orinda Results can be used to assess effectiveness of mitigation measures and inform concerned homeowners and future fire mitigation strategies

4 What impact would pine tree removal have on fire vulnerability for Sleepy Hollow homeowners? Photo Source: disasterandemergencysurvival.com RESEARCH QUESTION

5 RATIONALE 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?

6 BARK BEETLES

7 STUDY SITE

8 METHODOLOGY Grove of pines Corner of Normandy Ln. and Sleepy Hollow Ln. 600 View from study site 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

9 METHODOLOGY 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) Variables measured: Flame Length (feet) Crown Fire Activity (class) Heat per Unit Area (kj/m2) Rate of Spread (chains/hr) Data Analysis: Spatial changes (ArcGIS) Histogram comparisons (Excel)

10 FUEL MODELS: land use type Existing Condition Pine Mitigation 600

11 FUEL MODELS: land use type Existing Condition Pine Mitigation 600

12 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 height range Verifications of pines made through Google Earth Pro street view

13 CROWN FIRE ACTIVITY: class Existing Condition Pine Mitigation 600

14 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)

15 HEAT PER UNIT AREA: kj/m 2 Existing Condition Pine Mitigation 600

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

17 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%)

18 RATE OF SPREAD: chains per hour Existing Condition Pine Mitigation 600

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

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

21 FLAME LENGTH: feet Existing Condition Pine Mitigation 600

22 Assessment of changes in flame length over entire study area Reduction of: flames over 0.4 acres flames over 0.2 acres flames over 0.1 acres flames over 0.03 acres Increase in: 0-10 flames over 0.7 acres

23 FINDINGS 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: 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 ( chains per hour) to more manageable rates of spread (0-20 chains per hour) reduction from very large flame lengths (between feet) to moderate flame lengths (0-10 feet)

24 RECOMMENDATIONS Alert fire officials to potential bark-beetle related tree deaths 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