Wildfire and Flood Hazards, Using GIS Tools to Assess Risk

Transcription

1 Wildfire and Flood Hazards, Using GIS Tools to Assess Risk Floodplain Management Association Conference, Rancho Mirage, CA September 2015

2 Thoughts To Keep In Mind What advantages are there in looking at fire and flood hazards, together? What mitigation concepts work for fire and flood? What messaging or tools can we pull from fire risk assessment to apply to flood risk assessment, and vice versa? 1 Floodplain Management Association Conference, Rancho Mirage, CA, September 2015

3 Flood and Fire - Who Many of the same people who are interested in understanding flood risk are interested in fire risk assessment (just a selection below) 2 Floodplain Management Association Conference, Rancho Mirage, CA, September 2015

4 Wildland Fire and Flood Risk FIRE Over 32% of the U.S. population lives in the wildland-urban interface (WUI) (USDA Forest Service, 2013) Wildfire activity for 2013 increased 50% above average of past 4 years, doubling burn area of Losses due to wildfire statistically result in 100% loss to the homeowner FLOOD U.S. Population in SFHA??? Closest stat was ASFPM s 3% of population in a Coastal Flood Zone. Record Flood has been appearing more frequently in the news but are floods more frequent??? $1B+ events flooding listed many times, fire only a few ns/events 3 Floodplain Management Association Conference, Rancho Mirage, CA, September 2015

5 Risk Reports Risk Analysis is: Flood Rate Map 1% annual chance hazard Predictive Assesses current situation / ground conditions Data intensive Results that can be used to take action Flood Risk Map Economic Losses 4 Floodplain Management Association Conference, Rancho Mirage, CA, September 2015

6 Fire and Flood GIS Risk Factors FIRE Regional models National level data sets 30-m Grid Cell or use national level data Mostly summarized at Zip Codes we offer Parcel or Address Underwriting, point-ofsale renewal of insurance Not incident command and action FLOOD Community or HUC-8 Stream-by-Stream, localized data 2-ft contour accuracy, LiDAR points Interpreted for individual locations Flood insurance and community floodplain management, mitigation planning and disasters 5 Floodplain Management Association Conference, Rancho Mirage, CA, September 2015

7 Fire and Flood GIS Risk Factors FIRE (when evaluating a property) Roof Type and Configuration Attached structures (especially wooden) Exterior Wall Type Foundation Construction Type/Style Fireplaces Maintenance Condition Dwelling Type Method of HVAC Garages/Carports Freeboard FLOOD (Hazus UDF) Lowest Finished floor Elevation Occupancy Type Replacement Cost / Content cost Flood protection / Design level Foundation type Attached structures Year built Square footage House ignition zone radius 6 Floodplain Management Association Conference, Rancho Mirage, CA, September 2015

8 Freeboard vs Ignition Zone Historical Riverine Home Freeboard Achieved House Ignition Zone not achieved Before Do these actions swap one natural hazard risk for another? After 7 Floodplain Management Association Conference, Rancho Mirage, CA, September 2015

9 Fire and Flood GIS Risk Factors Fire Factors: FIRE Fuel / Vegetation Size and Shape Arrangement Moisture Content (dead or alive) Fire History Terrain Slope Weather Wind Precipitation FLOOD Regression Equation: You know these Terrain Precipitation Drainage Area Impervious Surface Slope more factors Hydraulics for the details 8 Floodplain Management Association Conference, Rancho Mirage, CA, September 2015

10 U.S. Population Living Near WUI 9 Floodplain Management Association Conference, Rancho Mirage, CA, September 2015

11 10 Floodplain Management Association Conference, Rancho Mirage, CA, September 2015

12 Data Sources Fire History Title: Fire History Source: U.S. Geological Survey Note: Fire patterns within landscape are based on interactions between vegetation dynamics, fire spread, fire effects, and spatial context. 11 Floodplain Management Association Conference, Rancho Mirage, CA, September 2015

13 Data Sources Precipitation Title: United States Average Annual Precipitation Source: National Atlas of the United States 12 Floodplain Management Association Conference, Rancho Mirage, CA, September 2015

14 Data Sources Fuel / Type of Vegetation Title: 13 Anderson Fire Behavior Fuel Models Source: U.S. Geological Survey 13 Floodplain Management Association Conference, Rancho Mirage, CA, September 2015

15 Data Sources LandCover Title: National Land Cover Dataset Source: USGS Note: Categories include agriculture, barren, developed, herb, shrub, sparse, tree, and water 14 Floodplain Management Association Conference, Rancho Mirage, CA, September 2015

16 Data Sources Slope (Elevation) Title: National Elevation Dataset Source: USGS NED 15 Floodplain Management Association Conference, Rancho Mirage, CA, September 2015

17 Data Sources Wind Title: National Wind Resource Assessment Source: US Department of Energy Note: Ratings are taken by wind power density 16 Floodplain Management Association Conference, Rancho Mirage, CA, September 2015

18 Methodology Factor Influence (%)* Vegetation 20 Fuel 20 Fire History 20 Precipitation 20 Wind 10 Slope 10 Factor Attributes Low (1) Medium (2) High (3) Very High (4) Vegetation Type 1 X Vegetation Type 2 X Vegetation Type 3 X * These rankings may be adjusted based on user input 17 Floodplain Management Association Conference, Rancho Mirage, CA, September 2015

19 Methodology Vegetation Fuel Model Slope WET LOW VEGETATION LOW RISK LESS FUEL LOW RISK GRADUAL SLOPE LOW RISK DRY BROADLEAF TREES HIGH RISK MORE FUEL HIGH RISK STEEP SLOPE HIGH RISK 18 Floodplain Management Association Conference, Rancho Mirage, CA, September 2015

20 Methodology Wind LOW WIND SPEEDS LOW RISK Fire History LONG FIRE RETURN INTERVAL LOW RISK Precipitation HIGH PRECIPITATION LOW RISK HIGH WIND SPEEDS HIGH RISK SHORT FIRE RETURN INTERVAL HIGH RISK LOW PRECIPITATION HIGH RISK 19 Floodplain Management Association Conference, Rancho Mirage, CA, September 2015

21 Wildland Fire Model Output 20 Floodplain Management Association Conference, Rancho Mirage, CA, September 2015

22 Image Courtesy of Yavapai County Flood Control District, AZ

23 Risk Report Web Application 22 Floodplain Management Association Conference, Rancho Mirage, CA, September 2015

24 Wildland Fire Hazard Risk Areas Rancho Cucamonga worked with CAL FIRE on Wildland Fire Risk Maps for the City Permit / Development / landscaping guidelines One more step to combine with flood risk? rict/high_fire_hazard_area.asp Interactive Map Viewer: ce/default.htm 23 Floodplain Management Association Conference, Rancho Mirage, CA, September 2015

25 Show Me My House ft Fuel Risk Rings 200-ft home ignition zone Freeboard or Depth Grid How much water up against your home? Photo realistic visualization helps make the message personal 24 Floodplain Management Association Conference, Rancho Mirage, CA, September

26 Used to seeing single natural hazard focused Mitigation Action Suggestions 25 Floodplain Management Association Conference, Rancho Mirage, CA, September 2015

27 Multi-Hazard Mitigation Actions Combine a risk assessment for many hazards? Fire Hazard Erosion Potential 26 Floodplain Management Association Conference, Rancho Mirage, CA, September

28 Post-Fire Flood Risk Fire decreases infiltration and increases runoff Graphic and content from Victoria Stempniewicz NAU Thesis: Evaluating Erosion Risk Mitigation Due to Forest Restoration Treatments Using Alluvial Chronology and Hydraulic Modeling Allowing more precipitation to reach the ground Soil-water storage is reduced Fire eliminates fine roots that bind soils together Potential for sediment transport 27 Floodplain Management Association Conference, Rancho Mirage, CA, September 2015

29 Post-Fire Flood Risk - Schultz Pamphlet - wnload/adwr-wildfire_insurance.pdf 28 Floodplain Management Association Conference, Rancho Mirage, CA, September 2015 Photos from azdailysun.com

30 Post-Fire Flood Risk Landslide / mudslide post-fire risk probability analysis azards/postfire_debrisflow/ 2015/ lake/ 29 Floodplain Management Association Conference, Rancho Mirage, CA, September 2015

31 Please continue to consider Fire and Flood risk do go together. Share common data layers They impact each other either Groups starting to look at the combined hazard with postfire/flood/landslide/debris flow risk Are there lessons we can learn from discussing fire risk in the flood hazard world and vice versa? Can mitigation options address more than one natural hazard and what does it take to get the conversation focused like that? Flames from the Rocky Fire approach a house on July 31 in Lower Lake, California. Justin Sullivan / Getty Images Questions? 30 Floodplain Management Association Conference, Rancho Mirage, CA, September 2015