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Proactive By Design.
Our Company Commitment
COASTAL DATA
APPLICATION
Projecting Future Coastal Flood
Risk for Massachusetts Bay
Bin Wang, Tianyi Liu,
Daniel Stapleton & Michael Mobile
2015 Coastal GeoTools

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 Overview of available data sources for coastal and
water resource engineers
 Overview of numerical hydrodynamic modeling
Outline
Objective: to present method and steps for site-specific
coastal flood hazard analysis
• Small budget
• Relatively short project schedule
• Use of published data by USACE NACCS and
other government agencies

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Background
Coastal Flooding
Erosion
Flood Damage Structural Damage

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Background
Need to identify/quantify flood hazards:
 stillwater elevations
 wave action
 environmental loads
 shoreline and nearshore response
To achieve coastal resiliency:
 critical infrastructure
 communities
 biohabitats
 natural resources
Coastal Resiliency

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Massachusetts Bay &
Cape Cod Bay
• Total Number of Cities/Towns = 53
• Population = 1.90 M (2010 Census)
• Historical Coastal Towns
Background

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Massachusetts Bay
Coastal Flood
Hazard
Background
“Nor-Easters”

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Hurricanes
Background
Massachusetts Bay
Coastal Flood
Hazard

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Available Data
South Shore Coastal Geomorphology: Beaches, Estuaries, Marsh,
Structures
GZA Coastal Engineering GeoTool

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Available Data
South Shore Coastal Geomorphology: Shoreline Change

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Available Data
North Shore Coastal Geomorphology: Beaches, Estuaries, Rocky
Shore, Scarps, Structures

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NOAA SLOSH Model • Hydrodynamic Model
• Develops hurricane
windfield
• NOAA developed DEMs
Available Data

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Available Data

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NOAA/NOS/CO-OPS Tide Gages
• Observed water levels, e.g., time series
for model validation/verification; extreme
value analysis; empirical simulation
technique (EST);
• Predicted tides and tidal constituents;
• Datum conversions (w/ Vdatum);
• Sea level trend
Available Data

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NOAA/NOS/CO-OPS 8443970: Boston Harbor
5
6
7
8
9
10
11
12
1 10 100 1,000
StillwaterElevation(feet,NAVD88)
Return Period (Years)
Observed Annual Maximum - Original Tide Data (ft, NAVD88) Observed Annual Maximum Adjusted w/ Sea Level Rise
Calculated Stage-Frequency Curve w/ Original Tide Data Calculated Stage-Frequency Curve w/ Sea Level Rise-Adjusted Tide Data
Hingham Harbor (FEMA 2012)
Generalized
Extreme
Value (GEV)
Available Data

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Available Data
FEMA Flood Insurance Study and Rate Maps

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Available Data
FEMA Flood Insurance Study and Rate Maps

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Wave Information Studies (WIS)
• Frequency analysis
• Time series
Available Data

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Wave Information Studies (WIS)
100-year return
period
significant deep water
wave height: +/- 35 ft
Available Data

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USACE North Atlantic Coast Comprehensive Study
(NACCS) Numerical Hydrodynamic Storm Surge and
Wave Models
USACE NACCS

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Site-Specific High Resolution Storm Surge, Wave and
Flood Modeling
Coupled ADCIRC + SWAN Models
Numerical
Hydrodynamic Modeling

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• NOAA or State GIS topographic &
hydrographic data layers (DEM)
• National or state land cover database
• NOAA COOPS tide gages – water levels
and other data;
• USACE Wave Information System (WIS)
– wave & wind gages
• National Climate Data Center - ground
climate/weather stations
• NHC Hurricane Re-analysis project – best
track data
• Other (e.g., USGS stream gage data)
Model inputs
and calibration
Model construction
Data Sources

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U.S. Coastal Relief Model (30-m)LiDAR Terrain Data (2009 Boston @ 1-m)
Note: datum conversions & units
Data Sources

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Land Use – building nodal attributes, Manning’s friction
values, surface roughness coefficients …
Data Sources
State: MassGIS LU2005 National: NLCD 2011 (v.2014)

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Tropical Cyclones:
• HURDAT / HURDAT 2
• Historical Tracks
• IBtrACS - Int. Best
Track Archive
• Others (e.g., RAMMB)
Data Sources
Time Series
Verification
Statistical analysis

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Extratropical Cyclones
Data Sources
Book: New England Weather, New England Climate (Zielinski & Keim, 2003)
February 7, 1978

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USACE NACCS ADCIRC+SWAN Coupled Grid
Numerical Model
FEMA Model Grids Refined for New England

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GZA High Resolution, Locally-Refined ADCIRC+SWAN
Coupled Grid
GZA High
Resolution Local Model
FEMA Region II Refined for Southern New England

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Model Validation
Hurricane Bob 1991
August 16 - 28
Landfall: 41.4N, 71.4W

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Validation – Hurricane Bob 1991
Model Validation
0
5
10
15
20
25
30
35
40
45
18 19 20 21
SignificantWaveHeight(ft)
Days in August, 1991
NDBC Buoy Station 44008
Observed Simulated
-3
-2
-1
0
1
2
3
4
5
6
18 19 20 21
WaterSurfaceElevation(ft,
NAVD88)
Days in August, 1991
Hurricane Bob Storm Surge Newport, RI
Observed Simulated

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Bearing 10 °
Rmax 35 nm
Vf 20 kt
Vmax 105 kt
DP 68 mb
Modeling Extreme (Very
Low Probability) Hurricane
Synthetic Hurricane

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Typical track
direction, similar to
historical events
Synthetic Hurricane

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Sea Level Rise
Note: The Commonwealth of Massachusetts has not officially adopted any SLC scenario.

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Synthetic Hurricane
Present Sea Level

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Synthetic Hurricane
2100 USACE High SLR

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Synthetic Hurricane
Present Sea Level 2100 USACE High SLR

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North Shore at
greater risk for
waves
Synthetic Hurricane

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1
2
3
4
5 -10
-5
0
5
10
15
0 1 2 3 4
ADCIRC+SWANCalculated
WL(ft,NAVD88)
Simulation Time (days)
Station 1 - Salem
Station 3 - Boston
Station 5 - Scituate
Peak storm tide
• varies in space
• synchronized
• Boston at greater risk
Synthetic Hurricane

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Impact of
Sea Level Rise
Peak Storm Tides for Selected Sea Level Scenarios
0
2
4
6
8
10
12
14
16
18
Salem Revere Boston Quincy Scituate
CalculatedStillwaterLevel(ft,
NAVD88)
Present
SLR Int.
SLR High
North South

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- Slightly nonlinear storm tide response to sea level rise;
- For non-extreme cases, approximation by linear superposition;
- For more extreme cases, numerical modeling needed
1.5
1.6
1.7
1.8
Salem Revere Boston Quincy Scituate
CalculatedStillwaterLevel
Increase(ft)
SLR Int. - Present
Input SLR Int.
4.8
4.9
5.0
5.1
Salem Revere Boston Quincy Scituate
CalculatedStillwaterLevel
Increase(ft)
SLR High - Present
Input SLR High
Impact of
Sea Level Rise

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USACE NACCS Data Output “Save” Points
Comparison with
USACE NACCS

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3
6
9
12
15
1 10 100 1,000 10,000
StillwaterElevation(feet,
NAVD88)
Return Period (Years)
Observed Annual Maximum Adjusted w/ Sea Level Rise Calculated Stage-Frequency Curve w/ Sea Level Rise-Adjusted Tide Data
Hingham Harbor (FEMA 2012) NACCS Boston Harbor MT
NACCS Boston Harbor HT
NOAA/NOS/CO-OPS 8443970: Boston Harbor; NACCS-
predicted flood-frequency curve
Comparison with
USACE NACCS
MT ~ HT

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Overland Wave Inundation:
CEDAS: ACES Module
Applying Model
Output

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Flood Inundation Models
Hydrodynamic Loads on
Protective Barrier
Maximum Flow Depth
(ft)
1.9
MaximumVelocity (ft/s) 1.7
Impact Force (pounds)
per linear feet
7.7
Applying Model
Output

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Estuary Circulation; sediment
transport
Applying Model
Output
Shoreline Processes
Beach Erosion

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Applying Model
Output
Resiliency Design

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Take-away
• Massachusetts Bay has significant flood
risk:
 Tropical cyclones and nor’easters
 Sea level rise
 Large population
 Critical infrastructure
• USACE NACCS: provides updated flood
projections
• NACCS can be coupled with local, high resolution
surge and wave models

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Bin Wang, P.E.
Technical Specialist
Norwood, MA
781-278-5809
Bin.Wang@gza.com
Daniel C. Stapleton, P.E.
Principal
Norwood, MA 02062
781-278-5743
Daniel.Stapleton@gza.com
Tianyi Liu, Ph.D.
Coastal Engineer Specialist
Norwood, MA
781-278-3819
Tianyi.Liu@gza.com
Michael A. Mobile, Ph.D.
Technical Specialist
Bedford, NH
603-232-8738
Michael.Mobile@gza.com
Thank You!

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Synthetic Hurricane