Update on Hazus AAL Study and Data Eric Berman - FEMA Tom Schweitzer– STARR PTS

Contributors Tom Schweitzer Dan Deegan Shane Parson PTS – STARR PTS – BakerAECOM Shane Parson PTS – RAMPP

Past Flood Risk Assessments: Pre-HAZUS Studies Donnelly Data – mid 1980’s: Ranking of communities Use for decisions on mapping restudies Property At Risk Data: Refinement of Donnelly Removed areas that would not be developed (water bodies) Lost data from previous effort

Average Annualized Loss (AAL) FEMA initiated the AAL Study in 2009 to provide a Nationwide Loss Dataset Level 1 conducted on every county in the contiguous United States using Hazus-MH for both Riverine and Coastal analysis Used national data sets for consistency within the analysis Losses based on building and contents

Summary of Average Annualized Loss (AAL) Study Hazus AAL Study Completed March 2010 Used Hazus-MH MR4 Losses for 48 states and the District of Columbia Included 3,109 counties Calculated losses for five return periods: 10-year / 50-year / 100-year / 200-year / 500-year Calculated average annualized losses (AAL) AAL losses extracted from HPR files at the Census block AAL losses complied by county, state, and watershed (HUC-8, April 2010 WBD) Usability analysis performed First national AAL flood loss estimation study

Summary of AAL Study 2009-10 Hazus-MH Flood Average Annualized Loss Estimation (AAL) was performed for continental U.S. Level 1 Analysis Inputs: County-wide regions 10 sq mile drainage area 30M USGS DEM Default Census data (GBS) Final Output included: Return period losses Total exposure Average Annualized Loss Annualized Loss Ratio Relative Average Annualized Losses by State

AAL Results Total Annualized Losses Estimated at 55 Billion: Includes both riverine and coastal Using NFIP program average annual losses and other source of annual flood loss data, sets a lower bound of the annualized flood loss at minimum of 10 billion annually. Relative Average Annualized Losses by State Annualized Loss Ratio by State

Hazus AAL Usability Analysis Hazus AAL Usability Analysis (Performed by the 3 FEMA PTS) Completed 4/2011 Analyzed several aspects of Hazus flood loss hazard development and calculation and understand constraints Analyzed Hazus procedures to see if there are factors that contributed to the high initial AAL loss number Can any of the procedures be quantified and used to adjust the AAL loss totals? Developed an understanding of the limitations of a level 1 Hazus analysis (10 sqmi) Is the AAL data a usable data set for Risk MAP?

Hazus AAL Usability Analysis SUMMARY Use of 30 M DEM - some issues in developing an accurate flood hazard, (only national topography data set) Use of the Census data is appropriate for this level of analysis (planning level) The weighted area method for losses can overstate losses 10 sqmi drainage area - though limiting, use of smaller threshold requires significantly more resources (processing time) Possible double counting of losses in coastal areas Weighted area method takes the total building stock of a census block and calculates the losses based on the percent of the census block flooded. This even distribution of the building values across the census block can over state losses at times.

Hazus AAL Usability Analysis SUMMARY AAL losses were overstated with 2 and 5 year return periods losses included in the AAL calculation (removed from final AAL estimate) AAL losses were recalculated outside of Hazus using the 5 return periods (10, 50, 100, 200, 500-year) losses AAL losses were calculated using Log normal* Should use only one cross-section for all return periods Data is appropriate for use in Discovery meetings, sequencing and general comparison of relative risk between areas * Hazus 2.1 uses a linear AAL calculation Note that the calculation used to recalculate the AAL with out the 2 and 5 year return periods used log normal and the newest version of Hazus 2.1 uses a linear calculation. The difference in the totals is negligible. The linear calculation was used for application programming reasons.

Average Annualized Loss Availability Data & Format Shapefile format Access Database Data available by census block (2000 Census) Data available by watershed (HUC) Certain data requires HQ approval

GIS Format Intended Uses: Identify flood prone areas and Communicate relative flood risk (building and content losses) Though there is specific dollar loss data with each Census block the data should only be used to represent and compare the relative losses within a community, watershed, county or state. This is because the AAL data was derived using course national data sets.

Use of AAL Values Loss values need to be shown as relative rather than absolute dollar amounts. Proper use of the AAL loss data. Notice relative scale used to represent the AAL data for comparison.

Discovery Meeting Discovery Map The AAL is appropriate for use on discovery maps to portray the location of various flood risk. (red pixeled area)

Current AAL Data Availability Annualized Losses by Census Block (2000 Census) Availability Data & Format Can be used to satisfy Discovery meeting requirements Certain data requires HQ approval

Flood Risk Assessment Purpose and Intended Uses Identify Areas and Communicate Relative Flood Risk: Flood prone areas Vulnerable people and property Provide Flood Risk $: Potential damage severity for different flood frequencies Identify locations with possible cost effective mitigation options Improve Estimates for Flood Risk $: Losses from Average Annualized Loss (AAL) Study Refined losses from new flood study depth grids Refined general building stock data from local sources

AAL Data Requirements – Appendix O Appendix O for Risk MAP Requires other data from the Hazus AAL data set Certain data requires HQ approval

AAL Data Requirements – Appendix O AAL Access table only provides annualize loss data for: Total Loss Building Loss – Total Contents Loss – Total L_RA_AAL requires the following to be extracted from AAL Study.HPR (Hazus) files: Data for all 5 individual return periods More detailed loss data fields (such as total, building, and contents losses divided into residential, commercial, and other) Certain data requires HQ approval

Flood Risk Data AAL data has been compiled into a single database for use in extracting the required data in Appendix O format We have develop a tool that performs this extraction into MS Access Databases This is the initial assessment data that is required to populate the Risk Database for use in producing Risk MAP non-regulatory products The new Risk MAP products require data from Hazus to populate the Risk MAP Database

Flood Risk Data We have develop an application that allow you to extract the data from the AAL results database Select your state and then county The application will then extract the fields and data required to populate the Risk Map Database This data canthen be imported into your Risk Map database Currently we are finalizing the data. It can be requested from the PTS contractor for your Region.

Flood Risk Assessment Delivered What are these Products? This will include the 1% (100-yr) composite results shown on the Flood Risk Map and community-specific summaries in the Report. 21

Flood Risk Map Elements On the Flood Risk Map, the 1% or 100-yr composite results are shown, along with symbology showing where new studies have been done.

Flood Risk Report Elements Here is a zoom-in of one of these tables in the report.

Moving Forward The process for compiling the new data into a national data sets has not yet been determined Additionally the process to stored and distributed this data nationally as yet been determined Currently we are looking at storing the data associated with Flood Risk Databases in the MIP until other means can be developed to house the information. The existing extracted AAL does not match the Risk MAP non-regulatory risk database