US Army Corps of Engineers BUILDING STRONG ® Consequence Assessment for Dam Failure Simulations Kurt Buchanan, CFM Economist Mapping, Modeling, and Consequences Center US Army Corps of Engineers Huntington, WV

BUILDING STRONG ® Overview  Corps Dam Safety Program overview  Consequence Estimation Using HEC-FIA (Flood Impact Analysis) ► Data inputs required ► Methodology used by the software ► Results  Indentifying Critical Infrastructure within dam failure inundation areas

BUILDING STRONG ® USACE Dam Safety Risk Assessment Activities  Screening ► Minimal effort, classify portfolio  Periodic Assessments and Issue Evaluation Studies ► Validate screening, identify path forward  Dam Safety Modification Studies (DSMS) ► Risk reduction alternative analysis  Critical Infrastructure Protection and Resiliency (CIPR) ► Aligned with DHS homeland security High Probability High Consequence Low Probability Low Consequence High Probability Low Consequence Low Probability High Consequence Increasing Risk Consequence Probability RISK = (Probability, Consequence)

BUILDING STRONG ® USACE Dam Safety Mapping, Modeling, and Consequences Team  Virtual team of technical experts from across the Corps  GIS specialists, hydraulic engineers, and economists  Provides a standard operating procedure, technical training, and quality reviews  Produces a dam break hydraulic model, consequence estimate, and inundation map for each project  Results in a quality standardized product to support the risk assessment process

BUILDING STRONG ® USACE Dam Safety Consequence Assessment Workflow New Risk Assessment 3 new “teams” MMC (H&H/Econ) 1.Generic dam break modeling 2.Consequence modeling (HEC-FIA) Risk Team (H&H/Econ) 1.PFMA specific dam break modeling 2.Consequence model refinement (HEC-FIA) Dam Break & HEC-FIA models District Team 1.Dam break modeling input and “QC” 2.Consequence modeling input and “QC”

BUILDING STRONG ® Consequence Estimation Corps HEC-FIA Software  GIS-based software program, currently beta version  Uses data from a HEC-RAS dam failure model (depth grids, hydrograph, cross sections, etc.)  Structure inventory can be developed using data from FEMA’s HAZUS program ► Tax parcel data or point shapefiles can also be used  Program gives a statistical estimate of direct damages and loss of life to individual structures

BUILDING STRONG ® Consequence Estimation HEC-FIA Variables  Warning System Curves ► Default lowest curve is the emergency broadcast system  Mobilization curves ► Default is a maximum of 98% of population mobilized ► Can be changed depending on expected evacuation capability  Evacuation velocity ► Modeled as a straight line from the structure to the nearest safe zone, average evacuation speed is set at an average of 10 mph  Warning time relative to the breach initiation

BUILDING STRONG ® Consequence Estimation Mobilization Curve Example

BUILDING STRONG ® Consequence Estimation Example of a HEC-FIA Model

BUILDING STRONG ® Consequence Estimation How HEC-FIA Works  For physical damages: ► Determine the inundation depth at the structure from the depth grid ► Apply the appropriate depth-damage curves based on structure type  For life loss estimate: ► Determine if population was warned and had time to mobilize from arrival time data ► Assign a fatality rate for remaining population based on inundation depth and structure type

BUILDING STRONG ® Consequence Estimation Fatality Rate Zones (1-story) Fatality rates are based on historical averages Chance Zone – 91% >FH + 15' Compromized Zone - 12% FH + 13' to 15' Safe Zone – 0.02% <FH + 13'

BUILDING STRONG ® Consequence Estimation Double Warnings  Downstream inundation is split into two warning zones ► No Fail Zone – Area flooded prior to or regardless of the dam failure (i.e. spillway flow) Population gets warned when flooding is predicted from heavy rainfall and will have more time to evacuate ► Fail Zone – Not flooded until after the dam fails Population is not at risk from normal flooding and will not have any reason to evacuate until a dam failure occurs or is predicted to occur

BUILDING STRONG ® Double-Warning Procedure  Must be implemented any time there is significant non-fail Population at Risk 13 TIME Overtopping Failure Expected Failure FLOW Failure Evac. Warning Major Flooding Forecast Major Flood Evac. Warning Damaging Release HEC-FIA WARNING ISSUANCE TIMES

BUILDING STRONG ®

Consequence Estimation Example HEC-FIA Model

BUILDING STRONG ® Consequence Estimation Results  Direct damage estimates to structures, contents, and vehicles  Population at risk during the day and at night  Loss of life during the day and at night  Agricultural damages  Results can be identified by locations/areas

BUILDING STRONG ® Consequence Estimation Results

BUILDING STRONG ® Critical Infrastructure Why it matters  Important to identify Critical Infrastructure and Key Resources (CIKR) that could be at risk from a dam failure  Impacts caused by damage to CIKR are not included in the direct damage estimate  Impacts can be cascading  Potential damage to CIKR can be included in planning and mitigated for if identified

BUILDING STRONG ® Critical Infrastructure Examples of CIKR  Chemical manufacturing facilities, power generation plants, medical facilities  Water, sewer, and power infrastructure  Police stations, fire stations, prisons, schools  Transportation and communication networks  Many, many others…

BUILDING STRONG ® Critical Infrastructure Corps Path Forward  Currently developing a GIS-based method to identify and prioritize CIKR assets in inundation areas using DHS datasets  Priority will be given to CIKR that could impact human life safety  Integrate CIKR information into the overall risk estimate of each dam  Communicate risk levels to CIKR owners and operators

BUILDING STRONG ® Summary  Corps Dam Safety Program overview  Consequence Estimation Using HEC-FIA (Flood Impact Analysis) ► Data inputs required ► Methodology used by the software ► Results  Indentifying Critical Infrastructure within dam failure inundation areas

BUILDING STRONG ® Questions?  My Contact Info: ► Kurt Buchanan ► ► (304)  Hydraulic Engineering Center Website: ►