Burn Site Evaluation following California Wildfires Thomas E. Spittler California Geological Survey

Concurrent Approaches I.Watershed-Scale Modeling A.USFS BAER & Rowe, Countryman & Story B.USGS Regression Models Cannon & others II.Site-Specific Evaluations CGS, this method

Cannon & others, 2003, Old Fire. Rowe, Countryman & Story, 1949

The Site-Specific Approach I.Systematically Evaluate Post-Fire Risks II.Consistently Document Conditions III.Consider a Wide Range of Concerns I.Interior Subwatersheds II.Other Landuses (Hiking Trails) IV.Deliver Product to the Correct People

The Site-Specific Approach I.Systematically Evaluate Post-Fire Risks II.Consistently Document Conditions III.Consider a Wide Range of Concerns I.Interior Subwatersheds II.Other Landuses (Hiking Trails) IV.Deliver Product to the Correct People

Site # Reviewer Date Address Quad Watershed/Drainage GPS location Sec., T., R., BL&M Photos: frames

Characterization Structure(s)/infrastructural element at risk: □ house □ business □ major road□ local road □ trailer □ tank □ culvert □ other

a.□ small watershed □ large watershed □ colluvial hollow □ steep slope □ cut slope □ other b. size ac. c. slope (average and range) d. □ channel channel grade Watershed hillslope feature characteristics:

Other Information Geology Geomorphology Percentage Slope Burned Burn Severity

Type of Potential Hazard Flood Sediment concentrated flood Debris torrent Possible future landslide Other

Likelihood of Occurrence High (if impacted by a storm) Medium Low

Possible Risks to Lives Possible Risks to Property Potential for Engineered Mitigation

KOA Devore USGS Photo by Sue Cannon

The Site-Specific Approach I.Systematically Evaluate Post-Fire Risks II.Consistently Document Conditions III.Consider a Wide Range of Concerns I.Interior Subwatersheds II.Other Landuses (Hiking Trails) III.Other Types of Landslides IV.Deliver Product to the Correct People

The Site-Specific Approach I.Systematically Evaluate Post-Fire Risks II.Consistently Document Conditions III.Consider a Wide Range of Concerns I.Interior Subwatersheds II.Other Landuses (Hiking Trails) IV.Deliver Product to the Correct People

SiteAt-riskStreetGPS locationHazardLikeli-Risk to livesRisk to property numberFeatureaddressLatitude NLongitude W hoodfirepre-existfirepre-exist 12109Houses & Green Valley Lane, Green Valley LakeN W Flood, debris torrent, future landslidesHigh ModHighMod 12110House 701 Ridge Way Green Valley LakeN W Flood, Sed- concentrated floodlow 12111House Falling Leaf Dr. Green Valley LakeN W Flood, Sed- concentrated floodModlow Mod 12112Houses & Angels Dr., Green Valley LakeN W Flood, Sed- concentrated floodlow 12113House & Falling Leaf Dr., Green Valley LakeN W Sed- concentrated flood, flood, future slideModHighModHighMod California Geological Survey Burn Site Evaluation Summary Fire Name: Bold where risks are Moderate or High

REQUIREMENTS Trained Technical Staff Cooperation Between Agencies Background Resources –Maps, Photos –Google Earth or A RC Explorer High-Quality GPS GIS Support

Conclusion Post-fire hazard assessments ► Watershed modeling ► Site-specific review Systematic evaluations Consistent reporting Considerations beyond floods Delivery to public safety officials