Dr. Shane Parson, PE, CFM, URS (RAMPP Team) Using HAZUS for the Flood Risk Assessment Dataset within FEMA Risk MAP Studies 2011 ASFPM Annual National Conference Louisville, KY Dr. Shane Parson, PE, CFM, URS (RAMPP Team)

Agenda Overview Average Annualized Loss (AAL Study) Risk MAP – Flood Risk Assessment Dataset Process AAL Data Refined HAZUS Data Composite Data Flood Risk Products Use: Database, Report, Map This presentation will provide more details on the development of the Flood Risk Assessment dataset. We will spend some time providing information about the AAL or Average Annualized Loss Study. We will also go through the process of how the Flood Risk Assessment dataset is develop starting with AAL data, conducting new refined HAZUS analysis, combining these into the Composite data, which is delivered through the Flood Risk Products. Finally, we will give a brief overview about access to AAL data for current projects and some of the guidance documents with more information on the process.

Flood Risk Assessment Data 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 So what is the purpose and possible uses for Flood Risk Data? We want to identify areas with flood risk and communicate what area have a higher relative risk. When we talk about risk, remember it is the combination of both floodprone areas with where people and property reside. When we calculate risk, we have a dollar estimate of losses for different flood return periods. These estimates help guide where we might look at mitigation. For Risk MAP, we want to improve the ways we estimate risk by using both AAL Study data and new risk analysis from refined HAZUS analysis.

AAL Study 2010 HAZUS-MH Flood Average Annualized Loss Estimation (AAL) was performed for continental U.S. using MR4 Inputs: County-wide study regions 30 meter DEM Default Census data Final Output included: Total exposure Average Annualized Loss Annualized Loss Ratio Therefore, the AAL or Average Annualized Loss Study was initiated to as a way to improve on previous attempts of getting an “apples to apples” flood risk comparison for the nation. What was the AAL Study? It was an out-of-the-box HAZUS Level 1 Study using HAZUS MR4 software for the continental US. By using HAZUS default data such as 30 DEM terrain data and HAZUS default General Building Stock information, the AAL Study was the first attempt by FEMA to model (not just approximate) risk for both riverine and coastal areas. Outputs from the study included information on total building exposure, total losses, and the loss ratio between these value (what percent of structures and their content were damaged). These result were both for individual return period events and then combining into an Average Annualized Loss value. This AAL loss value, as shown on this map, can the be used in a variety of ways in Risk Map, such as prioritization algorithms for Project Planning and Discovery and also for the Flood Risk Assessment Dataset. 4

AAL Usability for Risk MAP Initial study focused on providing state and watershed based results As Risk MAP looks to use more detailed results (census block level), an AAL Usability Analysis was conducted to better understand its limitations and refine AAL results as appropriate. However, like any model, the HAZUS MR4 model has limitations based on data availability, analysis capability, and schedules and budgets. When we took a closer look at the AAL study results, we wanted to make sure that the model limitation were well understood and documented, so that when the AAL data is used within Risk MAP we can better communicate what AAL IS and what AAL IS NOT. Therefore, a follow-up AAL usability study is current underway to document the AAL study limitations and possible restriction on AAL data usage.

Flood Risk Assessment Inputs, Outputs, and Delivery HAZUS AAL Data Source: FEMA Draft flood depth grids Source: Flood Depth Grid Analysis Enhanced data Source: Discovery / Local, State, Fed. GIS Outputs: Flood Risk Assessment dataset HAZUS AAL Data Refined HAZUS Data Composite Data (includes data used for Flood Risk Report and Map) Delivery: Drafts presented at Resilience Meeting Final delivered after Flood Risk review and discussions Incorporated within Flood Risk DB, Report, and Map The inputs to develop the FRA dataset are the AAL data, new flood depth grids, and any enhanced data. The outputs are the FRA dataset with include AAL data, refined HAZUS data, and the composite of the two. Delivery will be at or prior to Resilience meeting. Now let’s look at this on more detail. 6

Development of the Flood Risk Assessment Dataset in Risk MAP So how will AAL data be used to make the Flood Risk Assessment Datasets. Let’s look at our HUC-8 watershed.

This is a view from HAZUS for one of the counties in our watershed.

When the AAL was run, HAZUS was used to delineate streams

These streams or HAZUS reach were then the basis for developing flood depth grids for different return periods.

These depth grids were then intersected with the background inventory data to produce flood risk loss estimates for each census block. These losses can then be exported from HAZUS.

Here in a regular GIS we see our county

And the county within our watershed

When we bring in the HAZUS losses for each county and each return period, we can produce maps like this which show relative loss through the watershed.

Once each counties loss results are combined, we have a single watershed-based loss estimate. For example, this map may represent the 1% annual chance or 100-yr flood loss.

So, how do we incorporate new flood modeling to the AAL So, how do we incorporate new flood modeling to the AAL? First we start with our watershed

And determine where we have new modeling being conducted

In this case we have a small area with new depth grids.

We can zoom in and see this better within a particular county.

So now in HAZUS we can import this depth grid created by our new study

And run a HAZUS loss analysis for this depth grid And run a HAZUS loss analysis for this depth grid. See how HAZUS only created losses for those census blocks that intersected the depth grid.

We then export these losses from HAZUS

Select them and bring them into a GIS environment

And combine them with the AAL data to create a Composite dataset, representing the best available flood risk losses

When we zoom out, we can see our new composite dataset, where most of the data came from the AAL study, but there is some new data from our refine HAZUS analysis.

Enhanced Flood Risk Assessment Analyses Enhancements could include: Risk Assessments at site-specific locations Incorporation of locally-provided inventory data (first-floor elevations and/or parcel data) Additional sources of flood depth grids Supplemental HAZUS analyses or other types of analyses In addition to standard Flood Risk Assessment, a study may also have some enhanced elements. These could include doing site-specific loss calculates, use of better quality local data, developing improved depth grids, and conducted supplemental HAZUS analyses for things like critical facilities. 26

Refined HAZUS Data – Content Scalability Flood Risk Assessment   HAZUS analysis for reaches with new or updated studies where depth grids can be generated  Should include 10%, 4%, 2%, 1%, and 0.2% annual chance events and Annualized Loss  HAZUS GBS Losses (dollar losses, percent damage, business disruption) Enhancements   Additional events  Additional HAZUS loss calculations (infrastructure, critical facilities, user-defined facilities)  Use of local data to updated/supplement HAZUS data  Non-HAZUS analysis methods (needs to be able to produce the required output to populate the associated tables in the flood risk database) This slide shows some of the specific for the Refined HAZUS data. Notice that the list of the standard return periods. One thing to note is that the AAL data has 200-yr or 0.5% annual chance rather than the 4% or 25-yr year shown for Refined. Future HAZUS releases plan to update the annualized calculation process to use 25-yr rather than 200-yr. 27

Composite Data – Content Scalability Flood Risk Assessment   HAZUS Combination of AAL and Refined HAZUS Data  Should include 10%, 2%, 1%, and 0.2% annual chance events and Annualized Loss (may include more events)  HAZUS GBS Losses (dollar losses, percent damage, business disruption) Enhancements   Only included if results to be show in Flood Risk Report or Flood Risk Map This slide give some details for the final composite data set. Notice we only have 4 return periods that are the common ones from both AAL and refined. Also note that composite data will include enhanced results when those results are planned to be shown in the Report or Map. 28

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. 29

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.