Integrating Hazus into the Flood Risk Assessment

Transcription

1 Integrating Hazus into the Flood Risk Assessment GAFM Conference, March 22, 2016 Mapping Assessment Planning

2 Agenda What is Hazus & Risk Assessment? Census Block vs. Site Specific Analysis User Defined Facilities (UDF) Analysis Inventory Data Collection & Classification Flood Risk Database/Products Integration UDF Analysis Demo Q&A 2

3 What is Flood Risk Assessment? Assess potential losses or the consequences portion of the risk with: Information about local assets at risk of flooding Data about the physical features and human activities that contribute to that risk Evidence about where the risk is most severe 3

4 Flood Risk Assessment Data Sources Sources of risk information used to develop products FEMA generated Hazus analyses New engineering analyses (hydrology and hydraulics modeling) to develop new flood boundaries Locally-supplied data (see Appendix C for a detailed description) Sources identified during the Discovery process 4

5 What is Hazus? Free risk assessment software application from FEMA Extension to ArcGIS (currently 10.2 only) Run specialized flood risk assessments and/or what ifs a dam breaks or a levee fails 5

6 Hazus Methodology Flood Hazard Analysis Characterizes the spatial variation of flood depth in an area for riverine or coastal flooding Flood Loss Estimation The damage and loss piece of the model estimates structural damage to buildings and infrastructure through the use of depth-damage (vulnerability) curves. From these estimates, direct and indirect economic losses are calculated Results can be exported and presented as figures, tables, and maps 6

7 Hazus User Levels Level 1: Default data analysis. User-supplied data is limited and estimates are rough and are appropriate as initial loss estimates to determine where a more detailed examination is necessary. Level 2: Requires some user-supplied data. Combines local and default hazard and building data. A User Defined Facilities (UDF) analysis is a Level 2 analysis. Level 3: Advanced data and models analysis. Incorporates outside engineering and economic studies carried out using methods and software not included within this methodology. 7

8 Level 1 General Building Stock (GBS) GBS is the aggregated building stock used in Hazus Derived from Census data for residential and other sources for commercial and industrial inventory Uses broad assumptions 8

9 Level 1 General Building Stock (GBS) Hazus flood model comes with a suite of depthdamage curves from FIMA and Army Corps. Default depth-damage functions are assigned to each building by its specific Occupancy class 9

10 Level 1 General Building Stock (GBS) Damage estimation is calculated through area weighted damage estimates based on the depth of flooding within a given census block. 10

11 11 Level 1 General Building Stock (GBS)

12 Level 2 - User Defined Facilities (UDF)* Damages are determined by the depth of water at the location of the point representing a facility. Building and content losses are reported on a structure-by-structure basis. UDFs are not designed to replace engineering models or knowledge. UDF results are best used by summing all the UDF results for an area rather than using individual structure results. *Caution: Hazus designed as a regional loss estimation model, not necessarily designed for sitespecific analysis 12

13 UDF Analysis Methodology Hazus calculates a damage % for each structure by using the depth-damage curve for the structure parameters and depth of flooding at X/Y location. Hazus uses the damage % to calculate a $ amount of damage based on cost of replacement for each UDF. Ex: if a structure s replacement cost is $100,000 and Hazus determines that a Basement foundation type with a 2-ft first floor height in an area inundated to 3 feet has a 25% damage estimate, then Hazus calculates $25,000 in building damages. This procedure is calculated for each structure that is imported and the results are displayed as a table in Hazus. 13

14 UDF Analysis Workflow UDF: Analysis is run based on the geographic coordinates of each building s centroid or single point location and the attributes for the individual buildings. 14

15 UDF Analysis Steps 1. Acquire building data for study area 2. Pre-process data outside of Hazus 3. Import flood depth grid(s) into Hazus Single or multi-frequency 4. Create Scenario in Hazus 5. Delineate floodplain in Hazus 6. Import building data (UDF) into Hazus AS fc TABLE 7. Run analysis in Hazus 8. Review loss estimation results and export outside of Hazus 15

16 UDF Data Collection Tax Assessor Building Departments GIS Departments State insurance offices Commercial sources for property data 16

17 Pre-processing UDF Data The UDF import tool is very selective about the data types that can be imported Steps must be taken to clean the data into a format that Hazus will accept The dataset that defines the location of structures should be a building footprint centroids feature class Additional attributes necessary for the analysis are spatially table joined to this dataset 17

18 Populating UDF Attributes ATTRIBUTES Field Type Size Field Type Size CONTACT Text 40 BLDGTYPE Text 15 NAME Text 40 LATITUDE Double 16 ADDRESS Text 40 LONGITUDE Double 16 CITY Text 40 COMMENT Text 40 STATE Text 2 CONTENTCOST Currency 8 ZIPCODE Text 40 DESIGNLEVEL Text 1 PHONENUMBER Text 47 FOUNDATIONTYPE Text 1 OCCUPANCY Text 5 FIRSTFLOORHT Double 8 YEARBUILT Integer 2 SHELTERCAPACITY Integer 2 COST Currency 8 BLDGDAMAGEFNID Text 10 BACKUPPOWER Yes/No 1 CONTDAMAGEFNID Text 10 NUMSTORIES Byte 1 INVDAMAGEFNID Text 10 AREA Single 4 FLOODPROTECTION Long Int 4 OCCUPANCY BUILDING TYPE FOUNDATION TYPE FIRST FLOOR HEIGHT CONTENTS COST 18

19 Default* UDF Attributes Default constraints: Year Built = If unknown, look for the trends of surrounding buildings and set Year Built to the trend, or 1970 Occupancy = If unknown, look for the trends of surrounding buildings and set the Occupancy to the trend, or RES1 Number of Stories = 1 Foundation Type = 7 (slab on grade) *You will populate these default values 19

20 Viewing and Reporting Results All outputs are estimates, very important to convey this to others, especially decision-makers Provide results as rounded numbers or ranges do not provide exact numbers Include a disclaimer Can you verify your results? Are the results logical based on local knowledge? Accuracy of results will depend on the accuracy of the model inputs the hazard, inventory, and damage functions Garbage In, Garbage Out 20

21 21 Viewing and Reporting Results

22 Incorporating Hazus into RiskMap Products Identify Areas and Communicate Relative Flood Risk: Flood prone areas Vulnerable people and property Provide Flood Risk $ Losses: Potential damage severity for different flood frequencies Identify locations with possible mitigation options Improve Estimates for Flood Risk $ Exposure: Losses from Average Annualized Loss (AAL) Study Refined losses from new flood study depth grids Refined general building stock data from local source 22

23 Demo A demonstration of creating, importing and running a UDF analysis in the Hazus flood model. 23

24 Thank You Eric Coughlin Sr. GIS Analyst, Project Manager Atkins Raleigh, North Carolina (919)