1. International Workshop to Discuss the Science of Asset Management
Flood Risk and Asset Management using HEC-WAT with FRA
Compute Option
Michael K Deering, P.E., D.WRE
Senior Hydraulic Engineer
Hydrologic Engineering Center, CEIWR-HEC
International Workshop to Discuss the Science of Asset Management
9 December 2011

2. Flood Risk Management with HEC-WAT with FRA Compute Option
Systems Approaches and USACE Guidance
Introduction to the HEC-WAT
Introduction to HEC-WAT with FRA compute option
Economic and Performance Metrics
Columbia River Treaty HEC-WAT/FRA Application

3. Need for System Approaches with Risk Analysis
ER , Planning Guidance Notebook, 22 April 2000, requires systems approaches, "The planning process shall address the Nation’s water resources needs in a systems context…"
ER , Risk Analysis for Flood Damage Reduction Studies, 3 January 2006, requires risk analysis for all flood damage reduction studies,
"All flood damage reduction studies will adopt risk analysis…“
EC , Planning in a Collaborative Environment, 31 May 2005, provides revised procedures for conducting Corps water resources planning,
"Collaboration is the keystone of the Corps watershed approach…"
USACE Campaign Plan, Goals 1 - 4, require comprehensive systems approaches that include integrated sustainable solutions where decisions are risk-informed

4. Watershed Analysis Tool (HEC-WAT)
An overarching interface that allows the PDT to perform water resources studies in a comprehensive, systems based approach by building, editing and running models commonly applied by multi-disciplinary teams and save and display data and results in a coordinated fashion.

5. Hydrology Environmental Flood Damage Reservoir Hydraulics
Configurations are defined globally and are available to all the CWMS
standard models. 5

7. Interactive Schematic
Output Displays
Computation
Editors

8. HEC-WAT Model Integration
Integrate model and tools used during the analytical process
Hydrology - HEC-HMS, GeoHMS
Reservoir Operations - HEC-ResSim
Hydraulics - HEC-RAS, GeoRAS
Economics - HEC-FIA
Environmental - HEC-EFM
Statistical - HEC-SSP
Other software - GSSHA, FLO-2D, ADH, RiverWare
Share data across models
Involve modelers early in the study process; encourages a team approach

9. Development of FRA Compute Option
CEIWR-HEC began researching and creating a tool within the WAT that would perform risk management with parameter sampling and a life-cycle approach.
Provides a systems and life-cycle approach to plan formulation for assessing risks and uncertainties in simple systems as well as complex, interdependent systems.
Provides an effective tool for risk communication.
FRA will apply the Monte Carlo simulation & allow for a life- cycle type computation of consequences (economic and loss- of-life) and associated performance indices.
Incorporate new computational methodologies. 9 9

11. FRA Monte Carlo Sampling Sequence
For each project alternative, a single scenario of the project life cycle (e.g., 50 years) is simulated by sampling annual maximum flood events for the duration of the life cycle.
For agricultural damage, may sample season by season within each year, or sample a time of occurrence.
Hydrologic Sampling
Sample Historic Pool of events with associated Hydrograph Set or
Sample from frequency curve and hydrograph sets
Sample System-Wide Fragility Functions

12. FRM Monte Carlo Sampling Sequence (Continued)
Route Hydrograph Set
Consequence Area (CA) system Failures are based on hydraulics and fragility curves
Hydrographs will get adjusted as Dictated by Spills/Failures based on hydraulic model
Determine Flow and Stage at all Consequence Areas
2D Spreading can be performed in areas where needed
Compute Damage/Loss-of-Life for all Consequence Areas
Repeat

13. FRM Sampling Sequence Computing EAD by Event Sampling
Simple
Monte Carlo
Simulation
Reservoir Analysis
Channel Hydraulics
Levee Behavior
Hydrograph sets
Peak Discharge (cfs)
Exceedance Probability
stage
One Realization
Random choice of probability U[0,1] to "generate" event Method 1
Spreading Model
Inundation Mapping
Structure Inventory
Damage to Structures
damage
Damage(i)
After all realizations are computed you now have EAD:

14. Hydrologic Sampling - Method 2
pull out an event, use all its hydrographs, put it back…SHAKE 7 5 2 6 9 4 1 8 3 10 11 14 13 12 16 15 19 18 17 20 21
200-year
100-year
500-year 22
keep events whole

15. 20-years of 50-year life-cycle
after drawing 50 random U[0,1] values
200-year event

16. Probability of Levee Failure
FRM Load Distribution
Inflow Qi
Time Li
Stage (ft)
Probability of Levee Failure Qi Qb Qo
Outflow Qo
Reservoir 1
Reservoir 2

17. Inflow Spreading and Consequences
Inflow Qi
Time Li
Stage (ft)
Probability of Levee Failure Cn
Cn+1

18. Consequence Analysis - Inundation Mapping on Structure Inventory

19. Risk Communication Life-Cycle Economic Performance
Annual Exceedance Probability
Conditional Non- Exceedance Probability
Long-Term Exceedance Probability
Loss-of-Life
Risk Maps

20. EADw/o- EADw = DR BNet = DR - EAC N Y Y N EAC1 = Ctot / 500
EACn = Ctot / n*500
EACn+1 - EACn < Tol ?
EACn+2 = Ctot / (n+2)*500 N Y
EADw/o- EADw = DR
BNet = DR - EAC Y
EADn+2 = Dtot / (n+2)*500
EAD1 = Dtot / 500
EAD2 = Dtot / 2*500
EADn = Dtot / n*500
EADn+1 - EADn < Tol ? N

21. Life-Cycle Transients in HEC-FRM
Watershed Variables (HMS, RAS)
Operational Variances (ResSim, RAS)
Diminished structure values after event (FIA)
Increasing Structure values during rebuild (FIA)
Diminishing levee/component fragility over time (RAS)
Increased stability after O&M, repair, or rehabilitation (RAS)

22. Net Benefits with Uncertainty
EADw/o- EADw = DR (DR=Damages Reduced)
BNet = DR – EAC (EAC=Expected Annual Cost)
Determine BNet probability distribution by sampling DR and EAC distributions
Plan
Expected annual benefit and cost ($’000)
Net benefits ($’000)
Prob. Net
benefit is>0
Net benefit that is exceeded with specified probability ($’000)
Benefits
Cost
Mean
Std. dev.
0.75
0.50
0.25
20’ levee
355
300 55 68
0.80 8 54 99
25’ levee
500
400
100 88
0.88 45
104
164
30’ levee
570
550 20
116
0.55
-62 14 91
Channel
375 75 74
0.83 19 72
120
Detention basin
325
275 50 96
0.70
-17
113
Relocation
250
105 63
0.97 62
145

23. Annual Exceedance Probability - AEP
Key element in defining the performance of a plan. It is the probability that a specific capacity or target stage will be exceeded in a given year. For levees, the chance of failure or exceedance in any given year.
HEC-WAT calculates AEP at every grid cell and structure
AEP in this instance is probability of ground stage being equaled or exceeded
Creating a flood map from this data will be a simple raster calculation within a GIS program

24. CNP or Assurance
The index that a specific target (e.g. the top of a levee) will not be exceeded, given the occurrence of a specific flood event. 10 20 30 40 50 60 70 80 90
100
87% of 1% stages are less than 70'
87% of AEPs for 70' are less than 1%
3.63 5 10 15 20 25 46 52 58 64 70 76 83
1.81
2.07
2.33
2.59
2.85
3.11
3.37 99 90 75 50 25 10 5 2 1 .5 .2 .1

25. Long Term Exceedance Probability
The probability that one or more flood events will occur within a specified time period or the likelihood the target stage will be exceeded in a specified time period. The calculations are made directly using the binomial distribution (see EM ).
Long-Term Exceedance Probability = 1 – (1-AEP)n
AEP = annual exceedance probability
n = term of interest (e.g., thirty years)

26. Loss of Life
HEC-FIA can do Life Loss estimation. Care needs to be taken to make parameters match real life data (warning systems, population characteristics, flood evacuation plans)

27. HEC-WAT Application Columbia River Treaty Study
From HEC-WAT the FRM compute option will be used to calculate the expected annual damage for the assumed post base condition.
The models that are part of HEC-WAT watershed are being developed with the flexibility to evaluate numerous hydrologic scenarios, including climate change, and numerous operational modifications during any time period.
From HEC-WAT the FRM compute option will be used to calculate the expected annual damage for the assumed post-2024 base condition.
The models that are part of HEC-WAT watershed are being developed with the flexibility to evaluate numerous hydrologic scenarios, including climate change, and numerous operational modifications during any time period. 27

28. FRM
AEP Grid

29. Conclusion USACE will conduct risk assessments in a systems context
HEC-WAT/FRM will be a tool that performs these calculations
It will include systems approaches, event sampling, alternative analyses, structural and non-structural analyses, parameter sampling, life-cycle cost and economic analysis, loss-of-life, agricultural damage analyses.
Could be used nationwide for levee evaluations, levee assessments, and planning and design studies.

30. QUESTIONS? www.hec.usace.army.mil BUILDING STRONG®
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