... estimates of LOL frequently ignored ... the existing LO

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33256Estimating Loss of Life From Dam Failure

• David A. Moser

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Estimating Loss of Life from Dam Failure
Problem

• LOL estimates used in risk assessment of dams
• To evaluate the life safety risk
• To assess the life safety benefits
• To estimate the cost effectiveness
• All estimating equations suffer from sparse data
• Very aggregated--event level

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Estimating Loss of Life from Dam Failure
Problem cont.

• Few details of circumstances of individual events
• Warning time
• Uncertainty in estimates of LOL frequently
  ignored
• Traditional Corps data intensive methods to
  calculate population at risk (PAR) infeasible

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Estimating Loss of Life from Dam Failure
Objective

• Review and critique the existing LOL estimation
  approaches
• Improve and extend the database of historical dam
  failures
• Quantify uncertainty (random and sample error) in
  estimating models
• Develop improved LOL estimation model

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Estimating Loss of Life from Dam Failure
Objective cont.

• Apply improved estimating model to demonstrations
• Develop technical guidance on using LOL
  estimating model for dam failure risk assessment

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Estimating Loss of Life from Dam Failure
Approach

• Collect and analyze historical case studies
• Breaking down global PARs into sub-PARs
• Analyzing historical events in greater detail and
  recording insights into life-loss dynamics
• Estimating predictive the values from more than
  50 variables for each historical event

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Estimating Loss of Life from Dam Failure
Approach cont.

• Develop capability for using the US Census GIS
  data base with the DAMBRK (or its successor,
  FLDWAV) model output
• Results provide input for the LOL estimation
  model
• Quantify the additional PAR and other variable
  uncertainty contributions to predicted LOL
  uncertainty
• Test the new approach as part of site
  demonstration

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Estimating Loss of Life from Dam Failure
New Model

• 12-step algorithm for characterizing those
  aspects of a flood event that are pertinent to
  life loss
• Each PAR reduce to homogeneous subPar
• Par type (Pt)
• Excess evacuation time (E)
• Loss of shelter (Ls)
• Each subPar is then reduced to a threatened
  subpopulation (Tpari) using evacuation function

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(No Transcript)
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Some noteworthy observations

• Differences between case histories
• Short time needed to evacuate in many, but not
  all, cases
• Role of chance
• Role of safe havens (structures)
• Implications for evacuation

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Terminology

• PARPopulation at Risk
• Population that would be flooded if they took no
  measures to leave
• TPARThreatened Population
• Population remaining at risk after evacuation
• WtWarning Time
• Time from when warning is issued until arrival of
  flood

• RetRepresentative Evacuation Time
• Evacuation time for a particular Par
• EExcess Evacuation Time
• Wt Ret

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LIFE LOSS
EVACUATION
Evacuate
Survive
PAR
Remain
TPAR
LOL
Life Loss
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New Life Loss Estimation Model

DAMBRK

FLDWAV

HEC
-
FIA

HEC
-
V2.0

GeoRAS

MIKE 21

GIS Layers

Depth
v
.
t

Velocity
v
.
t

HEC

HEC

Travel Time

Structures

SubPAR
Land use

Definition

PAR
(t0)


Evacuation

Structures

Trans
.

model

SubPAR
(t0)

Performance

Simplified
Evac

Structures

d
amage

Model

PCDYNEV

Loss of
D
yn
.
Model

Loss of shelter

Shelter


SubPAR
at
arrival

Loss of Life

Survival/
Life loss

Loss of Life

Summary


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Velocity-Depth Relationships for Structural
Performance
depth
(m)
10
3 story
9
8
7
2 story
6
5
4
3
1 story
2
1
1
2
3
velocity (m/s)
(Source Green et al 2000)
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Evacuation Nonsuccess Factor (Ef) vs. Excess
Evacuation Time (E) (mins.)
- 0 Evac
- 100
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Identify Levels of Flood Exposure Based on
Life-Loss Patterns
evacuate ?
LOL
safe zone (Sz)
PAR
compromised zone (Coz)
remain (Tpari) ?
chance zone (Cz)
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Probability Distributions of Life Loss Rate for
Safe (sz), Compromised (coz) and Chance (cz) Zones
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FY02 Activities

• Complete parameterization of LOL predictive model
• Apply LOL model to Hills Creek demonstration
• Design document for application of GIS (census,
  warning time, other) with links to LOL model
• Technical procedures manual for predicting LOL
  for dam failure risk assessment
• Training materials for estimating LOL for dam
  safety