Beach-fx

Shore Protection Project Life Cycle Evolution

&

Economic Consequences

Shore Protection Project Performance& Economic Consequences

• Environmental Forcing • Morphology Evolution• Infrastructure Inventory & Valuations• Infrastructure Damage Functions

Integrate meteorology, coastal engineering, and economicsGoal:

Projects must be cost-justified• Benefit-cost analysis• Risk and uncertainty included in analysis

Formulation Requirement

Relevant Issues / Parameters

Beach-fx Features

Probabilistic Storm Generation

Impact of Storms on Beaches and Structures• Beach morphology change (profile)• Erosion, wave, and inundation damage

Long-term and Project-induced evolution• Beach morphology change (planform)• Vulnerability

Management Measures• Planned and Emergency Beach Nourishment• Infrastructure recovery rules

Transparency / Portability• Generalized Architecture• “glass-box”

Ease of Use• Intuitive, familiar interface to data and model• GIS linkages

Architecture• Access Database• Graphical User Interface• Monte Carlo Simulation

Beach-fx Development Approach

Broadly applicable, technically sound, non-proprietary modelsGoal:

Choose input data to treat as uncertain• Storm occurrence and intensity• Structure parameters (elevations)• Structure and Content valuations• Damage Functions

• Define distributions of uncertainty• Historically-based (storms)• Triangular (structure parameters/damage functions)

• Run multiple iterations over analysis life cycle

• Obtain overall statistics based on iterations

Beach-fx Incorporating Uncertainty

Beach-fx Data Driven Architecture

User Interface

ComputationalEngine

(Monte CarloSimulation Kernel)

Database

OutputData Files

Run

ReportsGraphics

Post-ProcessingAnimation

Within -SimulationAnimation

Beach-fx Event-based Monte Carlo Life Cycle Model

Life Cycle • number of years = iteration = series of events

= economic analysis period (e.g., 50 years)

Event • Behavior/Action at specific time in life cycle

Random (storms, structure failures) dune/berm evolution Fixed (monthly, weekly, daily) planform evolution Relative (events triggered by previous events) management/process

• Time moves forward, event to event

At each event• Simulate behavior, record activity, accumulate statistics

Each life cycle, record summaries

Each run, generate statistics on life cycle results

Beach-fx Environmental Forcing

Historical and Plausible Storm Events

• ID significant historical Tropical & Extratropical storm events DRP database

• Extract storm surge hydrograph

• Generate equilibrium tidal information DRP/CIRP tidal constituent database Develop tide elevation CDF and sample to extract three statistically

representative tidal ranges (low, mean, high)

• Combine storm surge hydrograph with representative cosine tide aligning peak surge at 4 phases of the tide signal.

• Develop wind waves for each historical storm WIS Database WISWAVE handcrafted hindcast

Beach-fx Environmental Forcing

0

10

20

30

0 10 20 30 40 50 60 70 80

T (

sec), W

ave H

t (ft)

Time (hr)

Martin County - WO Project

Wave Height MC_19991014_H1 Wave Period MC_19991014_H1

Beach-fx Morphology Evolution

Temporal variations in coastal geomorphology occur in• Cyclic patterns (seasonal) • Non-cyclic events (storms) • Longterm trends (planform evolution)

Non-cyclic events are viewed as short-term (mostly recoverable) storm-induced processes that result in beach profile changes.

Long-term trends give rise to historical shoreline change and (non-recoverable) beach planform changes. Can be historical or project induced (spreading-out of beach nourishment).

Beach-fx Morphology Evolution

Beach evolution within the Monte Carlo model relies a pre-computed Shore Response Database (SRD). The SRD contains estimated storm-induced changes in parameters that define a simplified beach profile.

• Berm width• Dune height• Dune width• Upland width

The SRD contains long-term shoreline change (applied shoreline change rates and estimated project-induced shoreline change.

Dune Width

Berm Width

DuneSlope

EquilibriumSubmerged

Profile

BermHeight

Beach-fx Modeling Coastal Morphology Change

Beach Profile ChangeTime scale: short-termProcess: cross-shore transportTool: SBEACH

Shoreline (Planform) Beach ChangeTime scale: long-termProcess: longshore transportTool: GENESIS

-4

-3

-2

-1

0

1

2

3

4

5

6

-50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180

Ele

vatio

n (m

)

Distance Offshore (m)

Storm-Induced Beach Erosion

Initial Profile Final Profile

Distance Across-Shore (m)

Ele

vati

on (

m)

Littoral Cell Boundary

Littoral Cell Boundary

Project Extent

Transport

Transport

Beach-fx Modeling Beach Profile Change

Beach Profile Response to Storms:Post Storm

• Erosion of berm• Scarping of dune face• Dune erosion lower crest elevation landward displacement

RecoveryBerm width and scarping low on the dune face is restored to near pre-storm conditions during weeks/months following storm passage. (No predictive capability for this process).

Major dune erosion does not recover.

Pre-storm Profile

Post-storm Profile

storm water levelPost-storm recovery

Beach-fx Characterization of the Study Area

Morphologically Representative Beach Profiles:

Representative beach profiles are our best estimate of the beach profile condition at the occurrence of any future storm, emphasis on the submerged profile

representative dune

Beach-fx Executing SBEACH Simulations

Populate Shore Response Database:

• The SRD provides estimates of beach profile response for all potential future beach profile conditions

• Simulate beach profile response to suite of historically-based plausible storms for range of anticipated future dune and berm configurations.

Beach-fx Execute GENESIS Simulations

Populate Shore Response Database:

• The SRD provides estimates of shoreline change and project-induced beach planform change.

• Within Beach-fx an ‘applied’ shoreline change rate is developed as part of the calibration process.

• The evolution of beach nourishment projects is simulated with GENESIS and the estimated time dependent project-induced shoreline changes are stored in the SRD.

100 ft Design Berm + 40 ft Advance Nourishment

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-4

-3

-2

-1

0

1

2

3

4

5

0 10,000 20,000 30,000 40,000 50,000 60,000

Longshore Location (m) [from East to West; 0 lies in Bay County, 60,000 in Okalossa County]

Change in C

ross-shore P

ositio

n [E

rosio

n] (m

/yr)

5 Year

5 Year Renourished (10 Year)

10 Year Renourished (15 Year)

Beach Nourishment

Beach-fx – Calibration Strategy• The average of multiple without-project life cycle simulations should

return the historical rate of shoreline change (+/-).

• Determine average rate of shoreline change produced by storms with specified planform shoreline changes set to zero.

• Adjust ‘applied’ shoreline change rate such that the combination of

storm-induced and applied shoreline change return, on average over multiple life cycle simulations, the historical rate of shoreline change.

-6.0

-5.0

-4.0

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

4.0

R

1-1

R

1-5

R

1-9

R1-

13

R1-

17

R1-

21

R

2-1

R

2-5

R

3-2

R

3-6

R3-

10

R3-

14

R3-

18

R3-

22

R3-

26

R

4-4

R

4-8

R

5-3

R

5-7

R5-

11

R5-

15

R5-

19

R5-

23

R5-

27

R5-

31

R5-

35

R5-

39

R5-

43

R5-

47

R5-

51

Reach

Shore

line

Chan

ge

(ft/yr

)

R1P1 R1P2 R2P1 R2P2 R3P1 R3P2

R4P1 R4P2 R5P1 R5P2 R5P3 HER

HER+SD HER-SD %TS=0 HER=0 Calibrated AER

Beach-fx Model Behavior for a Storm Event

For Each Storm Event (from Generated Sequence)Process all active profilesProcess all active reaches represented by each profile

For Each ReachPre-storm Berm Width / Dune Width / Dune HeightBest match in SRD (Lookup Profile)

Closest Dune Height (subset)Closest Berm Width (subset of subset)Closest Dune Width (single response)

Obtain lookup Responses from SRDBerm width, dune width, and dune height changeWave & Water level profiles, Erosion profile (for

damages)

Apply Profile Evolution Algorithm to Pre-Storm to obtain Post-Storm Profile

Beach-fx Model Behavior for a Storm Event

Recognize that the simplified profile does not exactly correspond to predicted beach profile shape so lookup changes can not always be directly applied.

Berm width reduction, dune width reduction, dune height reduction, upland width reduction

Scarping recoverable – low on the dune facenon-recoverable – scarping high on dune face

Apply Recovery to Post-Storm profile to get Post-Recovery profile (only berm width recovers)

Pro-rate recovery to complete at user-defined interval (global)

Beach-fx Geographical Hierarchy

Reach• Contiguous along shore• Represented by common morphologic

profile• SBEACH cross-shore reference

Reaches contain Lots• Represented as quadrilaterals

Lots contain Damage Elements• Representative point, length & width

505.4K

505.6K

505.8K

506.0K

506.2K

506.4K

506.6K

506.8K

507.0K

1.3694M 1.3696M 1.3698M 1.3700M 1.3702M 1.3704M 1.3706M 1.3708M

Reach: R1-1

North

ing

Easting

Beach-fx Project Hierarchy

D E D E

L ot L o t

R e ach 1B e a ch V a ria b les

P ro file 1

D E D E

L ot

R e ach 2B e a ch V a ria b les

D E D E

L ot

R e ach 3B e a ch V a ria b les

P ro file 2

P ro je ct

Beach-fx Damage Element Data

Location• Bounding Rectangle / Representative Point (Geodetic coord.)• Representative Elevation (distribution)• Ground offset (distribution)

Type• Usage (SFR, MFR, etc.)• Foundation / Construction / Armoring• Linear (walkover structures)

Economic• Structure and Content Value (distribution)• Rebuilding allowed?• Time to rebuild (distribution)

Beach-fx Damage Calculations

Damage Functions• IWR workshop / Expert elicitation• Single Family Residential

For each combination• Element type (house, walkway, pool, etc.)• Damage type (erosion, wave, inundation)• Foundation type• Structure / Contents

Define 3 Curves of • %Value Damaged = f(damage driving parameter) • Max, Min, Most likely• Combined impact (relationship)

Beach-fx Damage Functions

Wave DamageWaves - Structure not on piles

0

20

40

60

80

100

0 1 2 3 4

Difference between the top of the wave crest and the bottom of the lowest horizontal member (feet)

Dam

age

(per

cent

)

UpperProposed

Lower

Waves - Structure on piles (no enclosures)

0

20

40

60

80

100

-8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4

Difference between the top of the wave crest and the bottom of the lowest horizontal member (feet)

Dam

age

(per

cent

)

UpperProposed

Lower

Waves - Structure on piles (full enclosures)

0

20

40

60

80

100

-8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4

Difference between the top of the wave crest and the bottom of the lowest horizontal member (feet)

Dam

age

(per

cent

)

UpperProposed

Lower

Extent of damage dependent on the difference between the top of wave crest and bottom of the lowest horizontal structural member

Beach-fx Damage Functions

Erosion - Pile Foundation

0

20

40

60

80

100

0 10 20 30 40 50 60 70 80 90 100

Percent of Footprint Compromised

Dam

age

(per

cent

)

Upper

Proposed

Lower

Erosion - Shallow Foundation

0

20

40

60

80

100

0 10 20 30 40 50 60 70 80 90 100

Percent of Footprint Compromised

Dam

age

(per

cent

)

Upper

Proposed

Lower

Erosion Damage

Extent of damage for structures with shallow and pile foundations was dependent on the “percent of footprint” compromised.

Beach-fx Damage Functions

Inundation Damage

Extent of damage dependent on depth of water above the walking surface of the lowest main floor.

InundationWood frame with piles (full enclosures)

0

20

40

60

80

100

-10 -8 -6 -4 -2 0 2 4 6 8

Depth of water above walking surface (feet)

Dam

age

(per

cent

)

LowerProposedUpper

InundationWood frame with piles (no enclosures)

0

20

40

60

80

100

-3 -2 -1 0 1 2 3 4 5 6 7 8 9

Depth of water above walking surface (feet)

Lower=FIMAProposedUpper=N.O. pier

InundationWood frame without piles (no enclosure)

0

20

40

60

80

100

-3 -2 -1 0 1 2 3 4 5 6 7 8 9

Depth of water above walking surface (feet)

Dam

age

(per

cent

)

Lower=FIMAProposedUpper=N.O. pier

InundationConcrete and masonry without piles

0

20

40

60

80

100

-2 0 2 4 6 8

Depth of water above walking surface (feet)

Dam

age

(per

cent

)

Lower=FIMA

Proposed

Upper=N.O. pier

Beach-fx Damage Calculations

Damage Driving Parameter is specific to damage type• Inundation / Wave = water level – 1st floor elevation• Water level = max water elevation + setup + ½ max wave height)• Erosion - % of footprint compromised (compromised dependent on

foundation)

Calculate Damage Driving Parameter at DE location• Interpolate on 3 curves to define trangular distribution of % damage• Sample distribution – get % damage

Combined Damage Calculation (hard-wired)

Beach-fx Computational Flow

Year Season

Generate Storm Sequence For Year

For Each StormFor Each ProfileStorm Response Set From SRD For Each Reach Using Profile

Best Lookup in Storm Response Set Profile Changes / Wave, Water Level, and Erosion Profiles Revise Morphology For Each Lot In Reach

For Each Damage Element In Lot Calculate Individual Damages

Combined Impact

Beach-fx Model Output

Frequency Distribution of Damages

0102030405060708090

100110

0-10 10-20 20-30 30-40 40-50 50-60 60-70 70-80 80-90 90-100

Total Damages (Million Dollars)

Fre

queny o

f D

am

ages ...

Mean Damages: $30.3 million δ 16.1Median Damages: $27.0 million90% confidence interval: $10.9 – $64.0 million

Beach-fx Model Output

Mean Number of Emergency Actions: 6Median Number of Emergency Actions: 790% confidence interval: 3 to 12 Emergency Actions

Frequency Distribution of Emergency Actions Reach: R5-36

0

2

4

6

8

10

12

14

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Number of Emergency Nourishments

Fre

quency o

f E

merg

ency A

ctions

.

..

Beach-fx Limitations

• Simplified Profile

• Simplified Armoring

• Designed for Sandy Beach

• No Wave Attenuation by Structures

• No Breaching / Inlet formation

• Limited application experience