Workshop on Modeling and Managing Floods in Mountain Areas

IUSSTF L. Natoma Folsom, CA

Flood Risk Management and Adaptation to a Climate Uncertain World

Eugene StakhivJohns Hopkins Univ &

US Army Institute for Water Resources

Infrastructure Sectors affected by climate change whose engineering design requires new analytic

methods for risk, reliability and uncertainty analysis

Transportation (highways, culverts, bridges, rail, airports, ports, navigation, pipelines)

Water resources (dams, levees, irrigation, reservoir management, flood risk management, drought management)

Coastal Management (erosion, seawalls, groins, dredging)

Cold Regions (infrastructure design, permafrost changes, glacial dam outbursts)

Buildings and other structures (residential buildings, commercial, wind, roof damage)

Energy supply (power generation: hydropower, energy infrastructure design, wind engineering, thermal plant cooling, fuel supply)

Urban Water Systems (storm water management, municipal water supply and wastewater)

What Are the Issues?Dilemmas for Engineering regarding Climate Change: Incorporating Climate Science into Engineering

Practice Dealing with ‘Deep’ Uncertainty (unknown

unknowns) Engineering design standards Regulatory criteria Planning and evaluation techniques Methods for uncertainty analysis, and

transforming uncertainties into robust designs Development of Engineering Standards and

Regulations

Water Security and Disaster Reduction

Economic Damages in Bangladesh related to Mega-disasters: Adaptation to Uncertainties

The ‘ JANUS DILEMMA’ : The growing dominance of uncertain information on

Decision Analysis –esp for Climate change

PASTOutcomes Aspirational GoalsHindcasting ForecastingStationarity Non-stationarityRisk UncertaintyEmpirical statistics Stochastic analysisKnown Unknowns Unknown UnknownsTrends ScenariosReliability Robustness

Vulnerability Resilience

FUTURE

Cascading Uncertainties

Existing alphabet soup of confusing and overlapping satellite-based prediction

programs: who should sort all this out for us water managers and hydrologists?

GEWEX-Global energy and water cycle experiment CLIVAR-Climate variability and predictability (WCRP) GCOS-Global climate observing system GFCS-WMO Global Framework for climate services CLIPS-Climate information and prediction services CMIP-Coupled Model Intercomparison Project GEOSS-Global earth observing system of systems OSCAR- Observing Systems Capability Analysis and Review Tool PCMDI- gobbledegook ….Lawrence Livermore Lab Etcetera, etcetera, etcetera……..

GFCS

How should the WMO System look to water managers ?

SD=IWRM+IRBM+IFI+IDMP

WHYCOS

GEWEX

CLIVAR

WMO CLIMATE SERICES

USERS

Water agencies

Irrigation Districts

Municipal water NAV,

IRRIG,Hydro

RCC

NationalHydrometServices

Climate Adaptation: Top Down or Bottom up?

Do we need GCMs For Vulnerability

Assessments?

Water Sector Focus is on Risk Management for Climate Variability (which is foundation for CC)

Design, operations, rehabilitation require project evaluation & design criteria: combination of standards & risk analysis

Dam safety (convert PMP/PMF to risk-based designs) Levee design criteria ( SPF to risk-based designs) Shore erosion, coastal protection (PMH) Reservoir operating criteria, improved forecasting Reservoir/system water allocation changes Delineation of 100-year floodplains/NFIP Drought & Flood Contingency Mgmt (reservoir, urban) Emergency Operations/Advanced Measures (seasonally

anticipated snowmelt flooding, hurricanes, etc.)

In transition period, need new/extended methods for flood/drought frequency analysis under non-stationary climate, with trends.

Corps Reservoir Operations:Revising/Updating Regulations

Reservoir Master manual

Emergency Operations[ER 11-1-320]

Standard ProjectFloods

[EM 1110-2-1411]

Inflow Design Floods

[ER-1110-8-2]

Review of Completed Projects

[ER 1105-2-100;ER 1165-2-119]

Dam Safety Assurance Program

[ER 1110-2-1155]

Management of Water Control

Systems[EM 1110-2-3600]

Water ControlManagement[ER 1110-2-240]

Drought ContingencyPlans

[ER 1110-2-1941

Science, May 2006Vol 308

~1500-1600 AD

~400AD

GCM outputs

16

-20 -15 -10 -5 0 5 10 15 20

-40

-30

-20

-10

0

10

20

30

40

Percent Change Mean Annual NBS

Perc

ent C

hang

e An

nual

NBS

Sta

ndar

d De

viat

ion

Robustness Index Sampling Schemes on Lake Superior

Stochastic Results SamplingRegular Grid Sampling

[Pct (%)change in the mean NBS]Robust = Wider Range of acceptable performance in mean NBS change

Robust = Wider Range of acceptable performance in Variance NBS change

R

esili

ent

= W

ider

ran

ge o

f ac

cept

able

per

form

ance

inva

rian

ce

[Pct

[%]

chan

ge

in S

tdD

ev]

]

-15 -10 -5 0 5 10 15

-40

-30

-20

-10

0

10

20

30

40

50

Mean NBS (% Change)

NBS

Stan

dard

Dev

iatio

n (%

Cha

nge)

Superior Mean Annual NBS vs Standard Deviation for 50k Year Stochastic Set for 30 year Windows

Legend ° Upper C ♦ Lower C

17

Lake Superior

The means of most 30 year periods are within +/- 5% of long term average

Standard deviations vary a little more.

Range of the Stochastic NBS climate changes

Different methods for incorporating Climate Information into Water Sector

Project Planning/Design

GCM scenario analysis (test plans for robustness, resiliency, reliability)

Traditional Stochastic analysis of historic data

Hindcasting based on dendroclimatology& statistical ‘voodoo’ to extend records

Extending existing statistical tools & models (e.g. LP3 ‘fat-tailed’ distributions e.g.-GEV)

GCM downscaling and derived frequency analysis (not ready for ‘prime time’).

-400-200

0200400600800

10001200140016001800

1960 1980 2000 2020 2040 2060

(c)-200

0

200

400

600

800

1000

1200

1400

1600

1960 1980 2000 2020 2040 2060

Fig. 3 Annual NBS for: (a) Lake Superior; (b) Lake Michigan –Huron; (c) Lake Erie. Yellow – observed (EC residual method); blue – GLRCM simulation; pink – GLRCM simulation with bias correction.

year

NBS

(mm

ove

r lak

e)

0

200

400

600

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1000

1200

1400

1960 1980 2000 2020 2040 2060

(a)

(b)

NBS

(mm

ove

r lak

e)NB

S (m

m o

ver l

ake)

Superior

Michigan – Huron

Erie

GCM “Bias Corrections”For Great Lakes

Blue – Original model results

Yellow – Observed (historical)

Pink – what you get after bias correction

“You are not thinking; you are just being logical”Neils Bohr

For a good mathematical model it is not enough to work well. It must work well for the right reasons (on comparing the Ptolemaic and Copernican models of astronomy)Vit Klemes, “Common Sense and Other Heresies” (2000)

Fascination with automatic computation has encouraged a new set of mathematical formalisms simply because they now can be computed; we have not often enough asked ourselves whether they ought to be computed or whether they make any difference [Fiering, 1976]

It is comforting to recognize that.. resilient design can be achieved operationally without resorting to sophisticated or elaborate projections about climate change [Matalas and Fiering, 1977]

By speaking, by thinking, we undertake to clarify things, and that forces us to exacerbate them, dislocate them, schematize them. Every concept is in itself an exaggeration.” Jose Ortega y Gasset

"Life cannot wait until the sciences may have explained the universe scientifically. We cannot put off living until we are ready. Ortega y Gasset

***Necessary and Sufficient Conditions for Effective National IWRM: 10 ‘Commandments’

National Water Policy National Water Commission National Water Code (comprehensive and consistent

compilation of all regulations and policies) River Basin Commissions National Water Resources Management Plans Watershed User Associations (irrigation districts, flood

control districts, water quality, environment, etc.) ***Consistent Project Evaluation Guidelines [r, BCA] ***Consistent Engrg standards and hydrologic criteria ***Effective Regulatory Infrastructure ***Effective Institutional Enforcement Infrastructure

Conventional Mechanisms for Adapting to Climate Uncertainties

Planning new investments, or for capacity expansion (reservoirs, irrigation systems, levees, water supply, wastewater treatment)

Operation & regulation of existing systems: accommodating new uses or conditions (e.g. ecology, climate change, population growth)

Maintenance and major rehabilitation of existing systems (e.g. dams, barrages, irrigation systems, canals, pumps )

Modifications in processes and demands(water conservation, pricing, regulation, legislation)

Introduce new efficient technologies (desalting, biotechnology, drip irrigation, wastewater reuse, recycling, solar energy )

Functions/Elements of Water Resources Management

Horizontal Integrationamong Sectors

Integrated Drought

Mgmt

IntegratedFlood

Management

Urban Water Supply

EcologicalFlows

Hydro-power

CommercialNavigation

Irrigation& Drainage

Integrated Water Resources Management

Integrated River Basin (Watershed) Management

GoalObjective⇒

CriteriaSustainable Development Reduce Vulnerability

Econ. Envir. Equity SWB Safety ReliabilityMgmt.

Measure$ Costs

& Benefit

W.Q. Habitat Diversity

Income Distribution

Relocate Popul. at Risk

Frequency of Failure

MM1…

MMi…

MMn

•Structural / infrastructure•Legal / legislative•Institutional / administrative•Regulations (land use, zoning, standards)•Education

•Financial incentives, subsidies (+)•Taxes, tariffs, user fees (-)•Research and development•Market mechanisms•Technology development

Management ⇒Measures

DECISIONTHEORY

BCA

LP ELECTRE

WRAMMATSSWT

P&G

MAUT

FAULTTREE VOTING

P&SSVP

BENEFITCOSTTHEORY

SOCIALCHOICETHEORYSINGLE DM MULTIPUBLIC

‘Normative’ (Indicative) Evaluation Philosophies

The ‘Quadruple Discount’ Dilemma for Water Project Justification

Classical expected-value approach, extreme events with low probability of occurrence are given the same proportional weight/importance (in the multiobjective commensuration process) regardless of their potential catastrophic or irreversible impact.

Discount rate: for the present value of future benefits (r= discount rate of 2, 5, 7, 10 %)

‘expected annual damages’ (EAD): Discounting of low probability, high consequence events using flood/drought frequency analysis for damage assess.

Selection of Probability Distribution for EAD Maximize net benefits decision rule

Uncertainty and Flood Damage Calculation(Corps of Engineers Procedures - HEC-FDA;1992)

Floo

d St

age

(S)

Floo

d St

age

(S)

Flood Discharge (Q)

Flood Discharge (Q)

Freq

uenc

y

Freq

uenc

y

Flood Damage (D)

Flood Damage (D)

Q

S

P

Q

P

D

S

D

UEB - Upper Error Bound

LEB - Lower Error Bound

UEB

LEB

Hydrologic Excedance graph

0.0000

0.2000

0.4000

0.6000

0.8000

1.0000

1.2000

0 5000 10000 15000 20000 25000 30000 35000

Discharge (cfs)

Exce

edan

ce GEVLP3GumbelData

Discharge Recurrence Intervals for Different Frequency Distributions:

100-year event GEV distribution = 225-year event on LP3

0

5000

10000

15000

20000

25000

30000

35000

0 50 100 150 200

Recurrence Interval (years)

Disc

harg

e (c

fs)

GEVLP3Gumbel

R&U Flood Damages Analysis

Discounted Avg Annual Net Benefits (Benefits – Costs)

0.95

(25.0)

(40.0)

(155.0)

(30.0)

(20.0)

(300.0)

Long-term Risk of Failure

Lesson 1: to build confidence in the process, begin with the present

Get your facts straight about how the present water mgmt system contributes to the national economy and society

Develop a good understanding of the water balance – i.e.; where the water comes from; who uses it; how much, and where does it disappear?

AGREE on the current system demands & water balance

Work BACKWARDS – get the historical, and statistical basis of past water availability and uses

Then work FORWARD – via extrapolation and then multiple scenarios: compare, contrast, debate, familiarize

Exogenous scenarios (e.g. climate change,

Board planning/decision sessions IJC oversight and review sessionsOpen to PUBLIC: All Strategy and technical documents on Study

website Multiagency involvement to Technical Working Groups PIAG interaction Over 100 public meetings and written inputs 15 Circles of influence workshops Independent peer review of > 40 key technical

documents and models (academicians independently enlisted by ASCE; Canadian Water Resources Association) 3/18/2015 35

Lesson 3: Figure out the rules of evaluation –e.g. The ‘QUADRUPLE Discount’ Dilemma of

Water Project JustificationDilemma 1: classical expected-value approach, extreme

events with low probability of occurrence are given the same proportional weight/importance regardless of their potential catastrophic or irreversible impacts.

Dilemma 2: Discounting for the present value of future benefits (r= discount rate of 2, 5, 7, 10 %)

Dilemma 3: Selection of probability distribution further biases discounting of low probability, high consequence events using flood/drought frequency analysis for ‘expected annual damages’

Dilemma 4: what’s the appropriate decision rule?Maximize net benefits; min risk-cost; risk-cost-effectiveness?

Study identified six core elements of an effective adaptive management strategy – AFTER THE STUDYAdaptive management is essential for addressing the risks and uncertainties of future extremes in water levels in the Great Lakes.***requires leadership, commitment, perseverance and strengthened coordination among institutions on both sides of the international border.

Finis-Thanks (Questions?)