2015 Coastal GeoTools 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 Page 1
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 Overview of available data sources for coastal and water resource engineers Overview of numerical hydrodynamic modeling Page 2
Background Flood Damage Coastal Flooding Erosion Structural Damage Page 3
Background Coastal Resiliency To achieve coastal resiliency: critical infrastructure communities biohabitats natural resources Need to identify/quantify flood hazards: stillwater elevations wave action environmental loads shoreline and nearshore response Page 4
Background Massachusetts Bay & Cape Cod Bay Total Number of Cities/Towns = 53 Population = 1.90 M (2010 Census) Historical Coastal Towns Page 5
Background Massachusetts Bay Coastal Flood Hazard Nor-Easters Page 6
Background Massachusetts Bay Coastal Flood Hazard Hurricanes Page 7
Available Data GZA Coastal Engineering GeoTool South Shore Coastal Geomorphology: Beaches, Estuaries, Marsh, Structures Page 8
Available Data South Shore Coastal Geomorphology: Shoreline Change Page 9
Available Data North Shore Coastal Geomorphology: Beaches, Estuaries, Rocky Shore, Scarps, Structures Page 10
Available Data NOAA SLOSH Model Hydrodynamic Model Develops hurricane windfield NOAA developed DEMs Page 11
Available Data Page 12
Available Data 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 Page 13
Stillwater Elevation (feet, NAVD88) Available Data NOAA/NOS/CO-OPS 8443970: Boston Harbor Observed Annual Maximum - Original Tide Data (ft, NAVD88) Calculated Stage-Frequency Curve w/ Original Tide Data Hingham Harbor (FEMA 2012) 12 11 10 Observed Annual Maximum Adjusted w/ Sea Level Rise Calculated Stage-Frequency Curve w/ Sea Level Rise-Adjusted Tide Data Generalized Extreme Value (GEV) 9 8 7 6 5 1 10 100 1,000 Return Period (Years) Page 14
Available Data FEMA Flood Insurance Study and Rate Maps Page 15
Available Data FEMA Flood Insurance Study and Rate Maps Page 16
Available Data Wave Information Studies (WIS) Frequency analysis Time series Page 17
Available Data Wave Information Studies (WIS) 100-year return period significant deep water wave height: +/- 35 ft Page 18
USACE NACCS USACE North Atlantic Coast Comprehensive Study (NACCS) Numerical Hydrodynamic Storm Surge and Wave Models Page 19
Numerical Hydrodynamic Modeling Site-Specific High Resolution Storm Surge, Wave and Flood Modeling Coupled ADCIRC + SWAN Models Page 20
Data Sources 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 construction Model inputs and calibration Page 21
Data Sources LiDAR Terrain Data (2009 Boston @ 1-m) U.S. Coastal Relief Model (30-m) Note: datum conversions & units Page 22
Data Sources Land Use building nodal attributes, Manning s friction values, surface roughness coefficients State: MassGIS LU2005 National: NLCD 2011 (v.2014) Page 23
Data Sources Tropical Cyclones: HURDAT / HURDAT 2 Historical Tracks IBtrACS - Int. Best Track Archive Others (e.g., RAMMB) Statistical analysis Time Series Verification Page 24
Data Sources Extratropical Cyclones Book: New England Weather, New England Climate (Zielinski & Keim, 2003) February 7, 1978 Page 25
Numerical Model USACE NACCS ADCIRC+SWAN Coupled Grid FEMA Model Grids Refined for New England Page 26
GZA High Resolution Local Model GZA High Resolution, Locally-Refined ADCIRC+SWAN Coupled Grid FEMA Region II Refined for Southern New England Page 27
Model Validation Hurricane Bob 1991 August 16-28 Landfall: 41.4N, 71.4W Page 28
Water Surface Elevation (ft, NAVD88) Significant Wave Height (ft) Model Validation Validation Hurricane Bob 1991 NDBC Buoy Station 44008 45 6 5 4 3 2 1 0-1 -2-3 Hurricane Bob Storm Surge Newport, RI 18 19 20 21 Days in August, 1991 Observed Simulated 40 35 30 25 20 15 10 5 0 18 19 20 21 Days in August, 1991 Observed Simulated Page 29
Synthetic Hurricane Modeling Extreme (Very Low Probability) Hurricane Bearing 10 R max V f V max DP 35 nm 20 kt 105 kt 68 mb Page 30
Synthetic Hurricane Typical track direction, similar to historical events Page 31
Sea Level Rise Note: The Commonwealth of Massachusetts has not officially adopted any SLC scenario. Page 32
Synthetic Hurricane Present Sea Level Page 33
Synthetic Hurricane 2100 USACE High SLR Page 34
Synthetic Hurricane Present Sea Level 2100 USACE High SLR Page 35
Synthetic Hurricane North Shore at greater risk for waves Page 36
ADCIRC+SWAN Calculated WL (ft, NAVD88) Synthetic Hurricane 1 15 10 5 Station 1 - Salem Station 3 - Boston Station 5 - Scituate 3 2 4 0-5 0 1 2 3 4 5-10 Simulation Time (days) Peak storm tide varies in space synchronized Boston at greater risk Page 37
Calculated Stillwater Level (ft, NAVD88) Impact of Sea Level Rise Peak Storm Tides for Selected Sea Level Scenarios 18 16 14 12 North South 10 8 6 Present SLR Int. SLR High 4 2 0 Salem Revere Boston Quincy Scituate Page 38
Calculated Stillwater Level Increase (ft) Calculated Stillwater Level Increase (ft) Impact of Sea Level Rise 1.8 SLR Int. - Present Input SLR Int. 5.1 SLR High - Present Input SLR High 1.7 5.0 1.6 4.9 1.5 Salem Revere Boston Quincy Scituate 4.8 Salem Revere Boston Quincy Scituate - Slightly nonlinear storm tide response to sea level rise; - For non-extreme cases, approximation by linear superposition; - For more extreme cases, numerical modeling needed Page 39
Comparison with USACE NACCS USACE NACCS Data Output Save Points Page 40
Stillwater Elevation (feet, NAVD88) Comparison with USACE NACCS NOAA/NOS/CO-OPS 8443970: Boston Harbor; NACCSpredicted flood-frequency curve Observed Annual Maximum Adjusted w/ Sea Level Rise Hingham Harbor (FEMA 2012) Calculated Stage-Frequency Curve w/ Sea Level Rise-Adjusted Tide Data NACCS Boston Harbor MT NACCS Boston Harbor HT 15 12 MT ~ HT 9 6 3 1 10 100 1,000 10,000 Return Period (Years) Page 41
Applying Model Output Overland Wave Inundation: CEDAS: ACES Module Page 42
Applying Model Output Flood Inundation Models Hydrodynamic Loads on Protective Barrier Maximum Flow Depth (ft) 1.9 Maximum Velocity (ft/s) 1.7 Impact Force (pounds) per linear feet 7.7 Page 43
Applying Model Output Shoreline Processes Beach Erosion Estuary Circulation; sediment transport Page 44
Applying Model Output Resiliency Design Page 45
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 Page 46
Thank You! Bin Wang, P.E. Technical Specialist Norwood, MA 781-278-5809 Bin.Wang@gza.com Tianyi Liu, Ph.D. Coastal Engineer Specialist Norwood, MA 781-278-3819 Tianyi.Liu@gza.com Daniel C. Stapleton, P.E. Principal Norwood, MA 02062 781-278-5743 Daniel.Stapleton@gza.com Michael A. Mobile, Ph.D. Technical Specialist Bedford, NH 603-232-8738 Michael.Mobile@gza.com Page 47
Synthetic Hurricane Page 48