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2 Pietermaritzburg - December 25, dead 4,000 displaced Damages > $40 Million Greg Lovett /

3 Palm Beach County - January 10, 2014 >10-22 Inches of Rain in 24 Hours Required Rapid Response

4 Palm Beach County - January 10, 2014 Greg Lovett /

5 Outline NWS AHPS Flood Inundation Mapping FDEM Flood Inundation Mapping Project Considerations for Additional Flood Mapping in Florida GIS Approach to Flood Forecasting

6 NWS AHPS Flood Inundation Mapping Pros Well defined process Adopted nationally Based on FEMA models Used by emergency managers Cons Few sites Limited extents Doesn t consider localized flooding

7 NWS AHPS Flood Inundation Mapping

8 NWS AHPS Flood Inundation Mapping

9 FDEM Riverine Flood Warning in Florida Site Evaluation 168 NWS AHPS Reviewed flood impacts Forecast information Site Selection Identified 25 priority sites Classified - high / medium priority Selected 5 high priority sites to be analyzed for 2016

10 FDEM Riverine Flood Warning in Florida 2016 Inundation Mapping Blountstown (Apalachicola) Dowling Park (Suwannee) Luraville (Suwanee) Three Rivers Estates (Santa Fe) Holder (Withlacochee)

11 FDEM Riverine Flood Warning in Florida 2017 Inundation Mapping Elfers (Anclote) Fowler Avenue (Hillsborough) Branford (Suwannee) Astor (St Johns) Cocoa (St Johns) Trilby (Withlacochee)

12 Dowling Park Suwannee River Inundation Mapping SRWMD HEC- RAS Model Inundation Mapping 1 foot intervals Action Stage - 45 feet (NAVD 88) Major Flood Stage 60 feet (NAVD88)

13 Dowling Park Suwannee River

14 Consideration for Floodplain Mapping In Florida Depressional flooding Complicated systems Drainage area can change Source of flooding not always clear

15 Consideration for Floodplain Mapping In Florida South Florida Example 1,082 homes New floodplains proposed by FEMA Revised floodplains accounting for Florida conditions

16 Rapid Flood Screening What it s not Detailed Hydraulic Model Regulatory Product What it is Tool to Rapidly Assess Approximate Flooding Source of Approximate High-Risk Flooding Extents Tool that Addresses Current Local Needs

17 Processing Massive Terrain Datasets Typical Approach Break Up Dataset (tiling/chunking) Generalize Alternative Develop I/O-Efficient Processing Techniques

18 Rapid Flood Screening Model Inputs LiDAR-based DEM Runoff Coefficients Stormwater Infrastructure Range Rainfall Depths

19 Rapid Flood Screening Model Results Flood extent for all rainfall depths Depth of flooding Detailed understanding of drainage characteristics

20 Rapid Flood Screening Uses Rapidly Map Approximate Flood Risk Identify Priority Areas Choose Appropriate Flood Model and Scale Map Inundation in Real Time

21 Rapid Flood Screening Flood Elevation Accuracy ~ 1.2 ft Inundation Area Accuracy ~ 2.7%

22 Rapid Flood Screening

23 Rapid Flood Screening

24 Rapid Flood Screening

25 Rapid Flood Screening

26 Flood Warning More time for planning & prioritizing response Improved response times Automatically generate work orders

27 Localized Flood Warning Compare Flood Screening Results & NEXRAD Quickly Evaluate Spatial Rainfall Distribution Identify Areas with High Flood Risk Reduce Emergency Response Time Protect Critical Infrastructure

28 Localized Flood Warning

29 Localized Flood Warning

30 Localized Flood Warning

31 Localized Flood Warning

32 Localized Flood Warning Identify critical flood locations Analyze detailed model results Add points to flood warning system

33 Localized Flood Warning County-wide Key Flood Locations Visual warning of likely flood locations Focus for county response

34 Flood Forecast NOAA Rainfall Forecast 6-hour 24-hour 5 km x 5 km

35 Flood Forecast

36 Summary NWS AHPS Flood Inundation Mapping FDEM Flood Inundation Mapping Project Considerations for Additional Flood Mapping in Florida Rapid Flood Screening Approach to Flood Forecasting

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38 Questions Introduce yourself to your neighbor Discuss the following questions: What are some of the challenges you face in dealing with flood risk? How would real-time flood warning benefit your community/organization?