Consequence Assessment for
Dam Failure Simulations
Kurt Buchanan, CFM
Economist
Mapping, Modeling, and Consequences Center
US Army Corps of Engineers
Huntington, WV
US Army Corps of Engineers
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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
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USACE Dam Safety
Risk Assessment Activities
RISK = (Probability, Consequence)
 Screening
Probability
►
High Probability
High Probability
Low
Consequence
High
Consequence
Low Probability
Low Probability
Low
Consequence
High
Consequence
Consequence
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
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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
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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)
District Team
1. Dam break modeling
input and “QC”
2. Consequence
modeling input and
“QC”
Dam
Break &
HEC-FIA
models
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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
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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
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Consequence Estimation
Mobilization Curve Example
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Consequence Estimation
Example of a HEC-FIA Model
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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
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Consequence Estimation
Fatality Rate Zones (1-story)
Chance Zone – 91%
>FH + 15'
Compromized Zone - 12%
FH + 13' to 15'
Safe Zone – 0.02%
<FH + 13'
Fatality rates are based on historical averages
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Consequence Estimation
Double Warnings
 Downstream inundation is split into two
warning zones
Fail Zone – Area flooded prior to or regardless
of the dam failure (i.e. spillway flow)
► No
• 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
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FLOW
Double-Warning Procedure
Major
Flood
Evac.
Warning
Major
Flooding
Forecast
HEC-FIA
WARNING
ISSUANCE
Failure
TIMES
Evac.
Warning
Damaging
Release
Overtopping
Failure
Failure Expected
13
 Must be
implemented
any time
there is
significant
non-fail
TIME
Population
at Risk
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Consequence Estimation
Example HEC-FIA Model
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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
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Consequence Estimation
Results
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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
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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…
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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
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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
►
Kurt.L.Buchanan@usace.army.mil
►
(304) 399-5187
 Hydraulic Engineering Center Website:
► www.hec.usace.army.mil
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