Duncan FitzGerald

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Response of Sea Level Rise On Tidal Inlets
by
Duncan FitzGerald Boston University
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• Little Long-Term Data to Evaluate the Effects
• of Rising Sea Level on Tidal Inlets
• 1. Spit Breaching and Tidal
  Inlet Formation
• New Inlet, Cape Cod
• . Ocean City Inlet, Maryland
• 2. Backbarrier Subsidence
• Barataria Bay, Mississippi River Delta
• 3. Regional Uplift
• Copper River Delta Barrier System
• 4. Poldering of the Backbarrier
• . East Friesian Seegat
• 5. Short-term Sea-Level Rise
• Willipa Bay, Washington

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IPCC Scenarios of SLR, 2001
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(IPCC, 2007)
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(Ramstorf, 2007)
r .88
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Published rates of High, Low, and Total marsh
accretion
(Argow, 2006)
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Published rates of marsh accretion
(Argow, 2006)
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(Reed et al 2007 Report to Climate Change
Science Program)
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Backbarrier Evolution
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Mixed Energy Coasts
(Hayes, 1979)
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Mixed Energy coast of Northern New England
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Southern New Jersey Coast
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Virginia Coast
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Southern North Carolina

?





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Central South Carolina
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South Carolina and Georgia
South Carolina and Georgia
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Denmark North Sea
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Throat Cross Sectional Area (ft2) below msl
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1. Backshore Slope
Bay Size
2. Regional Topography
3. Sedimentation History of the Bay
BAY TIDAL PRISM
INLET SIZE
Frictional Factors
1. Shoreline Configuration
2. Shelf Width
Tidal
Range
3. Size Dimensions of Amphidromic System
4. Position in Amphidromic System
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(No Transcript)
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Nauset Inlet Cape Cod
Accommodation Space
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South Carolina
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(Hayes, FitzGerald, Hulmes, and Wilson, 1976)
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• Little Long-Term Data to Evaluate the Effects
• of Rising Sea Level on Tidal Inlets
• 1. Spit Breaching and Tidal
  Inlet Formation
• New Inlet, Cape Cod
• . Ocean City Inlet, Maryland
• 2. Backbarrier Subsidence
• Barataria Bay, Mississippi River Delta
• 3. Regional Uplift
• Copper River Delta Barrier System
• 4. Poldering of the Backbarrier
• . East Friesian Seegat

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Cape Cod, Massachusetts
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1985
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1986
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1988
1999
New Inlet Cape Cod
Growth of ebb-tidal delta sediment
starves downdrift shoreline
(Pendleton, 2002)
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Ocean City Inlet Maryland
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Ocean City Inlet Maryland
Growth of Ebb-tidal delta
From Stauble, 1997
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(No Transcript)
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Downdrift barrier rollover of Assateague Is.
(Williams et al., 1995)
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Mississippi River Delta Plain
Birdfoot Delta
Barataria Bay
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Barataria Bay
Mississippi River
Plaquemines Delta
LST
Lafourche Delta
LST
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Former Extent of Wetlands
1846-1853
Barataria Bay
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1956
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1973
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1993
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2005
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Land Loss Trends 1956-1978 19 km2
/yr 1978-1990 28 km2 /yr
0 8
N
(from Barras, 1994)
kilometers
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N
2 km
(List et al. 1994)

• Capture tidal prism from western
• and northern bay system
• Sinistral rotation of main ebb
• channel from 1880s to 1930s
• Enlargement of tidal inlets
• Formation of Pass Abel

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(No Transcript)
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Bathymetric Changes along Barataria Bay (from
List et al. 1994)

• 1880 to 1980 Trends
• Wetland loss and bay expansion
• Historical increase in tidal prism
• Enlargement of tidal inlets
• Growth of ebb-tidal deltas
• Barataria E-T-D gt 2 km

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Chugach Mountains
Copper River
Gulf of Alaska
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Copper River Delta Barriers
(Hayes, 1979)
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(Plafker, 1969)
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(from Hayes and Ruby, 1994)
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Copper River Delta Barriers
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(from Hayes and Ruby, 1994)
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(No Transcript)
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(No Transcript)
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1650
1750
1860
1960
Luck, 1975
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Poldering
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WANGEROOGE
SPEIKEROOG
LANGEOOG
Harle
Otzumer Balje
1650
1750
1860
1960
(FitzGerald et al, 1994)
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(No Transcript)
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Summary

• Accelerated SLR
• Conversion of marsh
• to open water
• Increase Tidal Prism
• Growth of Ebb-tidal
• delta
• Channel Scour
• Downdrift shoreline
• erosion

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Model of Barrier and Tidal Evolution in a Regime
of Accelerated Sea-Level Rise
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Tidal Dominance
Stage 1. Marsh Tidal Creeks
Stage 2. Open Lagoon
Flood-dominant
Ebb-dominant
Tebb / Tflood lt 1 ?A / ?T is large
Tebb / Tflood gt 1 ?A / ?T 0 Vebb /
Vflood gt 1
Vebb / Vflood lt 1
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Model of Barrier and Tidal Evolution in a Regime
of Accelerated Sea-Level Rise