FLOOD MODELING USING HAZUS IN ADA COUNTY A Hazard Mitigation Planning Perspective

1. FLOOD MODELING USING HAZUS IN ADA COUNTYA Hazard Mitigation Planning Perspective Northwest GIS User Conference – 2011 Ed Whitford, CFM Rob Flaner, CFM

2. Presentation Outline • Ada County Project Background • Introduction to Hazus-MH • Ada County Flood Model • The Versatility of Hazus • Questions

3. Project Background

4. Project Background • Paul Marusich - ACCEM • Doug Hardman - ACCEM • Rob Flaner – Lead Planner Tetra Tech • Ed Whitford – Risk Assessment Lead

5. Project Background Disaster Mitigation Act of 2000 (DMA) • Local Governments and Special Service Districts MUST Prepare Local Hazard Mitigation Plans (LHMP) to be Eligible for Post Disaster Assistance • Plan Must be Updated Every 5 Years

6. Project Background Ada County – LHMP Update 2010 • 22 local Governments participated in the planning process. • Plan assessed Risk from Flood, Dam Failure, Earthquake, Wildfire, Landslide, and Severe Weather. • Plan approved by FEMA October 2011.

7. Project Background Local Hazard Mitigation Plan Flood Hazard Elements • Identification of Hazards •  Flood and Dam Failure • Identification of Critical Facilities • Estimate of Recovery Time (days) • Characterization of Building Inventory •  Economic Loss ($$) • Short Term Shelter Needs, Debris Generation • Identification of Mitigation Projects • Based on Flood and Dam Failure Model Results

8. Introduction to Hazus MH

9. Introduction to GIS & Hazus MH Hazus IS AN ArcGIS EXTENSION

10. Introduction to GIS & Hazus MH Hazus IS AN ArcGIS EXTENSION • 4. Estimate Losses • 3. Determine Damage • 2. Define and Overlay Inventory • 1. Define Hazard: Flood Surface Land Surface

11. Level 1 DefaultDatabases Introduction to GIS & Hazus-MH Hazus IS AN ArcGIS EXTENSION ExpertSuppliedData Level 3 UserModifiedData Level 2

12. Introduction to GIS & Hazus MH HOW DOES HAZUS ASSESS RISK AND LOSSES? The Depth Grid  Raster data output  Cell values based on water depth • Inventory Data •  Census block characteristics •  Detailed structure information •  Critical Facilities Depth Damage Function  Relationship of water depth and first floor height of structures

13. Introduction to GIS & Hazus-MH WATER DEPTH DAMAGE FUNCTION Subtract ground surface from flood surface to determine flood depth throughout the study area Flood Elevation Ground Elevation Datum

14. Ada County Flood Model Overview

15. Flood Model Overview • Flood Hazard Data • FEMA DFIRM Data – County-wide • USACE – Boise River, Diversion Dam to Eagle Island • IDWR – Eagle Island Area • Terrain Data • Boise River and “Miles” Creek LiDAR • ADA County 2’ Contours

16. Flood Model Overview • Dam Failure Study • USACE - Lucky Peak Reservoir Terrain Data • 1/3 Arc Second DEM

17. Flood Model Overview Critical Facilities • Input from all 22 planning partners • Facilities included; medical, protective, schools, water/wastewater, transportation, government • FEMAs Comprehensive Data Management System (CDMS) used to update all Critical Facilities

18. Flood Model Overview • Building Specific Data • Ada County parcel centroids • Building characteristics extracted from County Assessor Database • year built • square footage • construction class • use code • number of stories • improvement value • Building First Floor Height Developed using effective FIRM date

19. Flood Model Overview • Building Specific data used to update Hazus General Building Stock (GBS) - Census Block Aggregated Data • Comprehensive Data Management System • Building Count • Square Footage • Building Value ($) • Content Value ($)

20. Flood Model Overview • Building Specific data also loaded as User Defined Facilities • Over 30,000 structures loaded into Hazus Flood Model

21. Flood Model Overview • Hazus flood model outputs used in the planning effort… • Building Specific (UDF Analysis) • Building Loss ($) • Content Loss ($) • Commercial Inventory Loss ($) • Census Block (GBS Analysis) • Displaced Households/Short Term Shelter Needs • Debris Generation, Vehicle Damage • Critical Facilities • Days to 100% Functionality, Percent Damage

22. Versatility of Hazus

23. Hazus Versatility • Hazus has evolved into a multifaceted planning tool • Regionally relevant Hazus models can be used for: • Public information • To support benefit cost analyses for mitigation grant applications • Risk based analysis of capital projects • “What if” scenarios • Planning (mitigation, emergency management, COOP, debris management)

24. Public Outreach • Hazus is a powerful public outreach tool • To gauge peoples perception of risk, you need to be able to show them how a hazard may impact them personally (“I never new !”) • A regionally relevant risk assessment is the key. • Can really promote the concept of mitigation • “Have you thought about……?” • People like having access to this type of information • Very media friendly!

25. Example Outputs

26. Risk Based Analysis of Capital Projects • Can use Hazus to perform “alternatives” analysis of capital projects. • Can compare losses avoided from one alternative to another. • “what if” scenarios • Can be a great tool to illustrate project benefits to garner political support.

27. Project ExampleRisk Based Analysis of Capital Projects King County, WA 180th-200th Levee alternative analysis • Used Hazus and BCAR to look at impacts for 3 setback levee alignments, plus an existing condition analysis. • Hazus used to model pre and post project impacts. • BCAR used to calculate annualized avoided damages. • Analysis included levee breach probabilities. • Analyzed 4 flows, 3 dam operational scenarios, for 4 levee alignments (that is 48 sets of depth grids!) • Over 1900 user defined facilities

28. Questions