CITY OF NEW YORK PARKS, NATURAL RESOURCES GROUP

CITY UNIVERSITY OF NEW YORK, THE GRADUATE CENTER

November 15, 2010

Salt Marsh Submergence and Restoration in New York City and

Implications of Accelerated Sea-Level Rise

ELLEN KRACAUER HARTIG

Idlewild Park Salt Marshes

Photo by Mike Feller, DPR-NRG

Jamaica Bay

Marshlands Conservancy

Long Island

ConnecticutNew York

New Jersey

New York City

Submerged Wetland Study Locations in New York City, Long Island, and Westchester

Shinnecock Bay

Stony Brook Harbor

Oyster Bay

Manhasset Bay

Pralls Island

Pelham Bay

Udall’s Cove

Alley Pond

Long Island SoundShelter Island

Hackensack

Meadowlands Fire Island

Atlantic Ocean

Long Island

Yellow Bar Hassock, 2000, photo by Vivien Gornitz

Submerging marshes at Jamaica Bay

(near JFK airport)

AA

A

B BB

CCC

Comparisons along Hutchinson River, Bx11951 199911974

Pelham Bay Park, near Coop City, the Bronx

Comparisons along Hutchinson River, Bx

16.27 Acres 6.33 AcresPelham Bay Park, near Coop City, 61% of 1974 Acreage, Av = 1.9% per yr loss

1974 2006

A

B

Comparisons along East River, Bx

A

B

A

B

1974 20061951

Pelham Bay Park, near Split Rock Golf Course, the Bronx

Pelham Bay Park Salt Marshes

Past Marsh Loss at Pelham Bay Park

Projected Marsh Loss at Pelham Bay Park

Comparisons at Udall’s Cove Park, Queens, NY1951 1974 1999 2005

A AA A

BB B

C

B

CCC

Udall’s Cove Park, Land-use Change and Impacts 1974 to 2006

2006 1974

Comparisons at Lemon Creek Park

B

A

CD

2006

B

A

CD

1974

B

A

CD

1951

Comparisons at Lemon Creek Park,

1924 to 2006

19241951197419992006

Vegetated Salt Marsh Loss, NYC and Vicinity1974 1999 Change since 1974

County/Park Hectares %Loss Loss Yr -1

BRONX (Pelham Bay Park)

Hutchinson River Marshes 20.7 11.4 44.9 1.8 %

Long Island Sound Marshes 31.1 20.7 33.3 1.3 %

QUEENS

Alley Pond Park 7.1 6.9 2.9 0.1 %

Jamaica Bay Islands 799.0 495.0 38.0 1.5 %

Udall’s Cove Park 8.2 5.1 38.1 1.5 %

STATEN ISLAND

Lemon Creek 4.9 3.5 (2006) 28.6 0.9 %

Saw Mill Creek (restored) 27.5 25.3 8.0 0.3 %

Pralls Island 5.6 2.4 (2006) 57.1 1.8 %

WESTCHESTER

Marshlands Conservancy 14.0 9.7 31.0 1.2 %Sources: NRG 2010; Mushacke 2006, Hartig 2002, 2004

Mechanisms of ErosionEnlarged Biogenic Holes

Marsh RetreatUndercutting

In–situ Slumping of Peat

Stressors

• Dredge and fill activity• Sediment loss • Changes in nutrient loading• Herbivory• Wave action (boats)• Sea Level Rise • Other

Brant

Source: NOAA, 2003 www.co-ops.nos.noaa.gov

Historic Mean Sea Level Trends

3.90 mm/yr

2.77 mm/yr

Relative Sea-Level Rise, Metropolitan East Coast (MEC)

Source: http://co-ops.nos.noaa.gov/sltrends/sltrends.shtml

Station SLR (mm/yr) YearsNew London, CT 2.25 1938-1999Bridgeport, CT 2.56 1964-1999Willets Point, NY 2.35 1931-1999Port Jefferson, NY 2.44 1957-1999Montauk, NY 2.78 1947-1999New York City, NY 2.77 1856-1999Sandy Hook, NJ 3.90 1932-1999

Name/CountyMarsh Zone SLR

Accretion (mm/yr) Source

Alley Pond (Queens, NY) high 2.4 3.5 Cochran et al. (1998)

Caumsett Park (LI, NY) high 2.3 4.1 Cochran et al. (1998)

Fresh Pond (Queens, NY) 2.4 4.3Clark and Patterson (1985)

Goose Creek (Bronx, NY) high 2.4 2.4 Cochran et al. (1998)

Hunter Island (Bronx, NY) high 2.4 1.1 Cochran et al. (1998)

Jamaica Bay (Queens, NY) 2.7 2.8 Kolker (2005)

Jamaica Bay (Queens, NY) 2.7 4.4 Kolker (2005)

Jamaica Bay (Queens, NY) high 2.7 5.0 Zeppie (1977)

Jamaica Bay (Queens, NY) low 2.7 8.0 Zeppie (1977)

Source: http://www.epa.gov/climatechange/effects/downloads/section2_1.pdf

Mean SLR Compared to Surface Accretion Rates

Sea Level Rise Projections for NYC, The Battery, (2000-2009) in cm)

Decade/GCMs 2020s 2050s 2080sIPCC-adapted Methods

Lower range 3.6 12.7 23.6Middle range 9.4 24.6 45.2Upper range 14.0 34.5 65.0

Rahmstorf/Horton Method + Local SubsidenceLower range 9.4 25.4 46.2Middle range 12.4 33.3 62.5Upper range 15.7 42.2 80.3

CRI Rapid Ice-Melt Sea Level RiseLower range 10 43 94Upper range 25 76 150

Note: Based on 3 scenarios (B1, A1B and A2) and 7 GCMs Source: Vivien Gornitz and Radley Horton, Columbia University, NASA/GISS, NPCC 2010

Marshes—Drown or Survive?SLR compared to Accretion Rates (in cm)

Decade 2020s 2050s 2080sAccretion rate L M H L M H L M HIPCC-adapted Methods for the NYC RegionLower range 0 6 12 -3 12 27 -8 16 40Middle range -5 1 7 -15 0 15 -29 -5 19Upper range -10 -4 2 -25 -10 6 -49 -25 -1

Rahmstorf/Horton Method + Local SubsidenceLower range -5 1 7 -15 0 15 -30 -6 18Middle range -8 -2 4 -23 -8 7 -47 -23 2Upper range -12 -6 0 -32 -17 -2 -64 -40 -16

CRI Rapid Ice-Melt Sea Level RiseLower range -6 0 6 -33 -18 -3 -78 -54 -30Upper range -21 -15 -9 -66 -51 -36 -134 -110 -86

L = Low (0.2 cm/yr), M = Medium(0.5 cm/yr), and H= High (0.8 cm/yr) accretion rates.

Simple model that accounts for accretion but neglects subsurface processes.

Activities

SETsSediment NourishmentSediment CoresHistoric loss analysisLandscape level Impact analysisNitrogen PathwaysRestoration Acquisition

Elevation Change

Surface processes– Sediment deposition– Sediment erosion

Subsurface processes– Root growth– Decomposition– Pore water flux– Compaction

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• Jamaica Bay Watershed Protection Plan• Wetland Transfer Task Force• PlaNYC 2030• Wetland Regulatory Gap Analysis• New York Panel on Climate Change (NPCC)

INITIATIVES

Research Needs• SET monitoring• Evaluation of different causes• LIDAR images• Bathymetric data• Permanent tide gauges• Projections of future sea level rise• Determine areas for inland migration

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ANTHROPOGENIC ROLEDredging / filling, boat induced waves, hard shoreline structures, sewage outfall; stormwater runoff

Synergistic Interactions Leading to Marsh Loss

Sediment deficiency,

erosion, slumping, tidal pool

enlargement

Salt marsh to mud flat conversion

DIMINISHING SALT

MARSHES

Water quality changes &

nutrient enrichment

CLIMATE CHANGESea-level rise

ECOLOGICAL CHANGESSea lettuce and ribbed

mussel increase, herbivory, (e.g. brant grazing)