Updated Total Exposure in Floodplain (TEIF) Method. Cynthia McCoy, FEMA Region X James Mawby, RAMPP (Dewberry)

Transcription

1 Updated Total Exposure in Floodplain (TEIF) Method Cynthia McCoy, FEMA Region X James Mawby, RAMPP (Dewberry)

2 What Are We Doing? Saving lives! Protecting property! 2

3 Need - Alternative Approach to Evaluate Potential Risk FEMA Region III utilizes multiple parameters to prioritize Risk MAP communities for engagement to increase resilience. At-risk population, existing relationships, level of potential risk The Average Annualized Loss (AAL) study has been used to identify and compare at risk communities. LIMITATIONS: Based on the 2000 Census, Countywide study regions, and utilized coarse 30 meter DEM No Risk? CHALLENGE - The AAL underestimates losses even when used for relative comparison Especially in coastal communities. Ex. Bethany Beach, DE (Sussex Co) AAL reports NO coastal flood losses THEREFORE the AAL does not meet our needs, and requires an alternative approach Enhanced HAZUS for entire Region (or at least by States?) Other lower-cost solutions, such as a TEIF analysis! 3

4 History 2010 AAL Concerns that AAL underestimated losses Especially in coastal communities. 4

5 New Approach - Total Exposure in Floodplain (TEIF 1) New Method to Estimate Exposure Method includes proportioning FEMA HAZUS 2010 Census Block Building Exposure by proportion covered by Special Flood Hazard Area (SFHA). Step 1 Assign Community ID Number (CID) to each respective Census Block. Step 2 Intersect Census Block Building Exposure with the SFHA layer and proportion the Exposure Value based on the percent area of the block within the SFHA. Step 3 Summarize values to the Community-level. 5

6 TEIF 1 Step 1 Step 2 Step 3 Intersect & Proportion with SFHA Summarize 25% Census Block $1M Building Value Approx. $250k Sum all by Community 6

7 Need for Improved TEIF Approach Local jurisdictions prioritized to address gaps in resources; 1. Natural hazard mitigation plan expires in 2016 or 2017 with limited Grant funding to support a robust risk assessment; 2. No updated flood mapping or flood risk products through Risk MAP in development; 3. High exposure and population in flood hazard areas, in relation to all communities within the State; 4. Minimal to no GIS capacity or GIS data to develop a refined flood risk assessment. 7

8 Updated Approach TEIF 2 New Method to Estimate Exposure Method includes distributing FEMA HAZUS Census Block Building Exposure to Building Footprints, Building Points or Address Points. Step 1 Proportionally Distribute 2010 Census Block Building Dollar Values To Buildings based on Building Points; alternatively based upon area of the footprints, when available. Step 2 Intersect with the SFHA layer and proportion the Building Dollar Values based on the percent area of the building in the SFHA. Step 3 Summarize values to the Community-level and provide losses by structure 8

9 TEIF 2 Using Building Points Step 1 Step 2 Step 3 Intersect with SFHA 2 Buildings Intersecting SFHA Census Block $1M Building Value Approx. $143k each $286k Loss Proportionally 9

10 TEIF 2 Using Building Footprints Step 1 Step 2 Step 3 $255K Intersect with SFHA 2 Buildings Intersecting SFHA $370K Census Block $1M Building Value Exposure value/building assumes 1 story $625K Loss 10

11 Extracting Building Footprints from LiDAR Data planar surface recognition Source: PAMAP Aerial Photography (2 D) provides a visual interpretation of on the ground features. Source: Google StreetView Source: PAMAP LiDAR Data ( 3 D) provides the ability to automate feature extraction of planar surfaces. 11

12 Automated and Manual Process using TerraScan Software and ArcGIS Automated Part 1 TerraScan Software (runs on MicroStation) Building Classification Tool Input needed: Point rich LiDAR file (.las) file with ground classified. Manual Part 2 Automated process is not fool proof. It s incredibly cost efficient, but not 100 % accurate. There will be omission (missing footprints) and commission (footprints where no building exists) errors. Manual clean up involves spending time with an aerial photo and intensity imagery derived from the LiDAR data. Produces rough polygon shapes through export to ArcGIS. Automated process can clean up rough outlines. Rough Realistic 12

13 TEIF 2 Limitations Communicates the potential economic losses (structural) from flooding. Model Limitations Building Data is static and represents data from one point in time. May not reflect current development. Building Exposure distributed from the Census Block to each structure. Does not reflect the actual value Intended for relative comparison of losses If gaps exist in Hazus State inventory, structures didn't receive exposure value Requires update Using Effective FIRM. Static dataset Risk is not limited to this hazard extent 11

14 TEIF 2 Delivery Document Map Package Summary Excel Spreadsheet Webinar & Live Demo 14

15 TEIF 2 Informing Local Mitigation: Crater Richmond, VA 15

16 TEIF 2 Informing Local Mitigation: Crater Richmond, VA Colonial Heights: Emergency Manager We need this analysis for Colonial Heights (GIS position vacant). Crater PDC Planner/GIS staff person may support getting the building footprints digitized to facilitate TEIF2.0 analysis. Don t know how it would be funded but will be adding to the HMP as a Mitigation Action to the list of Actions for our community: Mitigation Action - Complete building footprint data layer to enable TEIF2.0 analysis in Special Flood Hazards Areas. Sussex County: Emergency Manager While attending the Hazard Identification and Risk Assessment (HIRA) review meeting for our HMP along with our Building Official, Community Development Department Manager and Deputy County Administrator, the TEIF 2.0 results were demonstrated. It is a highly impressive analysis. The County is in the process of procuring ArcGIS and the Community Development Manager will likely be the lead to utilize this data moving forward along with other GIS assistance from the Crater PDC GIS Staff. Town of Stoney Point: Emergency Manager The Town experiences really bad flooding due to inadequate drainage from Interstate 95. This will enable us to better target residences for mitigation using FEMA HMA grants and leverage VDOT for solutions. City of Richmond: Emergency Manager & Emergency Planner This is a powerful tool which will allow us to focus on priority flood prone properties. We want to assure that our GIS support staff can participate in the WebEx or have access to a recording. Dewberry: HMP-HIRA Project Manager, Associate This analysis is valuable, relatable and powerful. For these reasons, we are using TEIF-2.0 results for the Richmond Regional Crater Planning District Commission 2017 Hazard Mitigation Plan Update HIRA. 16

17 Additional Applications of TEIF Develop a relative comparison of potential flood loss for Public Officials and homeowners Graphically visualize areas and populations of highest risk to inform resource allocation for pre-disaster planning Does an at risk area include the community s primary employer, the central business district, or the local School/City Hall/Hospital/Firehouse, elderly community or community of ESL citizens? Enhance State and Local Mitigation Plans Overlay essential facility layers to determine which may loose function, and others which may need to supplement the loss. Does this require a coordination plan? Prioritize hazard mitigation projects and help screen for costeffectiveness in FEMA mitigation grant programs Do projects exist in the highest risk areas? Can a project be written for multiple buyouts or elevations located within one block? Identify areas in need of more refined risk assessments 17

18 Additional Applications of TEIF Onset of a Risk MAP project Inform engagement priorities aid team in making more informed resource decisions Identify highest risk communities Marketing tool Generally, more accurate risk assessment than AAL from perspective of relative risk (i.e., this community has more risk or exposure than others) Illustrate to communities the value of developing enhanced HAZUS risk assessments through Risk MAP Used to Prioritize CAV (Community Assistance Visits) meeting schedule for FEMA Staff. Supplement AAL with TEIF Non-regulatory HAZUS Risk Assessment product development Another risk assessment tool for communities to consider May help inform project scope needs by identifying need for enhanced HAZUS analyses in some project areas 18

19 Questions and Contact Info Cynthia McCoy FEMA Risk Analyst Gerard (Gerry) Aiken FEMA Risk Analyst James Mawby RAMPP Technical Staff Other Previous Contributors Glenn Locke Mike McGeehin 19