analysis of storm-tide impacts from hurricane sandy in new york

Wind speed, in miles per hour

6050403020100

U.S. Department of the InteriorU.S. Geological Survey

Scientific Investigations Report 20155036

Prepared in cooperation with the Federal Emergency Management Agency

Analysis of Storm-Tide Impacts From Hurricane Sandy in New York

Front cover. A, Vehicles partly submerged at an entrance to a flooded parking garage in the Financial District of Manhattan; photograph courtesy of Frankie Torres / Flickr. B, Sailboats stranded in a street in Great Kills, Staten Island; photograph courtesy of the BoatUS Marine Insurance Program. C, Strength and direction of Hurricane Sandys ocean surface winds on October 28, 2012. Wind speeds above 40 miles per hour (mi/hr) are depicted in yellow, above 50 mi/hr are in orange, and above 60 mi/hr are in red; wind directions are indicated by black arrows. Map is modified from National Aeronautics and Space Administration (2013) produced with data from a radar scatterometer on the Indian Space Research Organizations Oceansat-2.

Back cover. A, A boardwalk swept off its pilings in Rockaway, Queens; photograph courtesy of John Huntington / Shutterstock. B, The 168-foot John B. Caddell water tanker aground in a parking lot in Stapleton, Staten Island; photograph courtesy of Sean Sweeney. C, A vehicle swept off a street in Great Kills, Staten Island; photograph courtesy of Rob Gross / Flickr. D, A boat stranded on the railroad tracks at Metro Norths Ossining Station on the Hudson Line; photograph courtesy of the Metropolitan Transportation Authority of the State of New York / Flickr.

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https://www.flickr.com/photos/frankietfotografia/8142461527/http://www.shutterstock.com/pic-133512764/stock-photo-damage-caused-by-hurricane-sandy-to-the-rockaway-boardwalk-queens-new-york.html%3Fsrc%3DGr8KXbFBqV5TGmd1trUskQ-1-2https://www.flickr.com/photos/robgross/8145998112/in/album-72157631888599273/%20Metropolitan%20Transportation%20Authority%20of%20the%20State%20of%20New%20York%20/%20Flickr%20Metropolitan%20Transportation%20Authority%20of%20the%20State%20of%20New%20York%20/%20Flickr


By Christopher E. Schubert, Ronald Busciolano, Paul P. Hearn, Jr., Ami N. Rahav, Riley Behrens, Jason Finkelstein, Jack Monti, Jr., and Amy E. Simonson

Prepared in cooperation with the Federal Emergency Management Agency

Scientific Investigations Report 20155036

U.S. Department of the InteriorU.S. Geological Survey

U.S. Department of the InteriorSALLY JEWELL, Secretary

U.S. Geological SurveySuzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2015

For more information on the USGSthe Federal source for science about the Earth, its natural and living resources, natural hazards, and the environmentvisit http://www.usgs.gov/ or call 1888ASKUSGS.

For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprod/.

Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner.

Suggested citation:Schubert, C.E., Busciolano, Ronald, Hearn, P.P., Jr., Rahav, A.N., Behrens, Riley, Finkelstein, Jason, Monti, Jack, Jr., and Simonson, A.E., 2015, Analysis of storm-tide impacts from Hurricane Sandy in New York: U.S. Geological Survey Scientific Investigations Report 20155036, 75 p., http://dx.doi.org/10.3133/sir20155036. ISSN 2328031X (print)ISSN 2328-0328 (online)

http://www.usgs.govhttp://www.usgs.gov/pubprodhttp://dx.doi.org/10.3133/sir20155036

iii

Acknowledgements

The authors thank the Federal Emergency Management Agency (FEMA) Region II for support and cooperation under the Stafford Act (42 U.S.C. 5121 et seq.). The assistance of many individuals is greatly appreciated. In particular, the temporary monitoring network deployment and high-water-mark flagging and surveying campaign were undertaken by U.S. Geological Survey (USGS) staff from more than 14 USGS science center offices and 2 USGS storm-surge coordination cen-ters. The authors would also like to highlight the leadership of Alan Springett, risk assessment team lead of FEMA Region II, and Robert Mason, acting chief of the USGS Office of Surface Water, in articulating the need for this novel analysis. Valuable coordination and assistance dur-ing the investigation were provided by Brian Lacasse, Craig Skalet, Austen K. Cutrell, and H.E. Gene Longenecker III of FEMA and J. Andrew Martin of Dewberry/Risk Assessment, Mapping, and Planning Partners. Thoughtful comments on this manuscript were provided by David Bjerklie and Tristen Tagliaferri of the USGS.

iv

ContentsAcknowledgements ......................................................................................................................................iiiAbstract ...........................................................................................................................................................1Introduction.....................................................................................................................................................2

Purpose and Scope ..............................................................................................................................2Meteorological History of Hurricane Sandy ....................................................................................2

Analysis of Storm-Tide Impacts From Hurricane Sandy .........................................................................7Peak Storm-Tide Elevation ..................................................................................................................7

Comparison With Historical Storms .........................................................................................7December 1992 Noreaster ...............................................................................................7Tropical Storm Irene .........................................................................................................16Historical Peak Water-Level Elevations ........................................................................16

Comparison With Annual Exceedance Probabilities ...........................................................16Storm Surge .........................................................................................................................................30

Storm-Surge Magnitude Associated With Peak Storm Tide ..............................................30Magnitude and Timing of Peak Storm Surge ........................................................................30

Extent of Storm-Tide Inundation .......................................................................................................30Mapping of Inundation Extent .................................................................................................30HAZUS Flood Loss Analyses ....................................................................................................42

Summary and Conclusions .........................................................................................................................42References Cited..........................................................................................................................................49Glossary .........................................................................................................................................................75

Figures 1. Map showing location of study area in New York and tracks of Hurricane Sandy,

Tropical Storm Irene, and the storm of December 1113, 1992, in the North Atlantic region ...............................................................................................................................3

2. Map showing locations of permanent and temporary monitoring sites and high-water-mark sites that documented the storm tide of Hurricane Sandy in New York .......................................................................................................................................5

3. Map showing the strength and direction of Hurricane Sandys ocean surface winds on October 28, 2012 ...........................................................................................................6

4. Map showing peak storm-tide elevations produced by Hurricane Sandy in New York counties ........................................................................................................................9

5. Schematic diagram showing Federal Emergency Management Agency coastal flood hazard zones and effects of wave heights on base flood elevations ......................10

6. Maps showing A, differences in feet between peak storm-tide elevations, and B, differences in percent between peak storm-tide elevations, produced by Hurricane Sandy and the storm of December 1113, 1992, in New York ..........................13

7. Maps showing A, differences in feet between peak storm-tide elevations, and B, differences in percent between peak storm-tide elevations, produced by Hurricane Sandy and Tropical Storm Irene in New York .....................................................21

8. Map showing selected annual exceedance probabilities for peak storm-tide elevations produced by Hurricane Sandy in New York counties .......................................29

9. Maps showing A, storm-surge magnitude associated with the peak storm tide, and B, magnitude of the peak storm surge, produced by Hurricane Sandy in New York counties ......................................................................................................................33

v

10. Maps showing extent of storm-tide inundation from Hurricane Sandy in New York counties that was derived from U.S. Geological Survey (USGS) storm-tide data available for A, National Hurricane Center Sea, Lake, and Overland Surges from Hurricanes model hindcast product dated October 31, 2012, B, Federal Emergency Management Agency (FEMA) interim high-resolution product based on USGS data available from storm landfall through November 11, 2012, and C, FEMA final high-resolution product based on USGS data available from storm landfall through February 14, 2013 .........................................................................................................37

11. Maps showing Federal Emergency Management Agency (FEMA) Hazus Program estimated total building stock losses due to storm-tide inundation from Hurricane Sandy in selected New York counties for inundation depicted in A, National Hurricane Center Sea, Lake, and Overland Surges from Hurricanes model hindcast product dated October 31, 2012, B, FEMA interim high-resolution product based on U.S. Geological Survey (USGS) data available from storm landfall through November 11, 2012, and C, FEMA final high-resolution product based on USGS data available from storm landfall through February 14, 2013 .....................................................43

12. Graph showing Federal Emergency Management Agency Hazus Program estimated total building stock losses due to storm-tide inundation from Hurricane Sandy in selected New York counties .....................................................................................46

13. Graphs showing differences between Federal Emergency Management Agency Hazus Program estimated total building stock losses due to storm-tide inundation from Hurricane Sandy in selected New York counties ........................................................46

Tables 1. Peak storm-tide elevations produced by storm of December 1113, 1992, at 27

high-water-mark sites, and peak storm-tide elevations produced by Hurricane Sandy at nearby sites in New York ..........................................................................................11

2. Peak storm-tide elevations produced by Hurricane Sandy, Tropical Storm Irene, and historical peak water-level elevations, dates of occurrence, and periods of record at 19 permanent monitoring sites in New York .........................................................17

3. Peak storm-tide elevations produced by Hurricane Sandy and Tropical Storm Irene at 23 temporary monitoring sites in New York .......................................................................18

4. Peak storm-tide elevations produced by Tropical Storm Irene at 10 high- water-mark sites, and peak storm-tide elevations produced by Hurricane Sandy at nearby sites in New York ......................................................................................................19

5. Peak storm-tide elevations produced by Hurricane Sandy at 24 permanent monitoring sites, and the corresponding Federal Emergency Management Agency flood elevations for the 10-, 2-, 1-, and 0.2-percent annual exceedance probabilities (10-, 50-, 100-, and 500-year recurrence intervals) in New York .........................................24

6. Peak storm-tide elevations produced by Hurricane Sandy at 43 temporary monitoring sites, and the corresponding Federal Emergency Management Agency flood elevations for the 10-, 2-, 1-, and 0.2-percent annual exceedance probabilities (10-, 50-, 100-, and 500-year recurrence intervals) in New York .........................................26

7. Peak storm-tide elevations produced by Hurricane Sandy at 346 high-water-mark sites, and the corresponding Federal Emergency Management Agency flood elevations for the 10-, 2-, 1-, and 0.2-percent annual exceedance probabilities (10-, 50-, 100-, and 500-year recurrence intervals) in New York. .................................................51

8. Storm-surge magnitude associated with the peak storm tide, and magnitude and timing of the peak storm surge, produced by Hurricane Sandy at 18 permanent monitoring sites in New York ....................................................................................................31

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[Inch/Pound to International System of Units]

Conversion Factors

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)inch (in.) 25.4 millimeter (mm)foot (ft) 0.3048 meter (m)mile (mi) 1.609 kilometer (km)

Flow rate

mile per hour (mi/h) 1.609 kilometer per hour (km/h)

DatumVertical coordinate information is referenced to the North American Vertical Datum of 1988 (NAVD 88) and the National Geodetic Vertical Datum of 1929 (NGVD 29).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Elevation, as used in this report, refers to distance above the vertical datum.

AbbreviationsBFE base flood elevationFEMA Federal Emergency Management AgencyHWM high-water markNAVD 88 North American Vertical Datum of 1988NGVD 29 National Geodetic Vertical Datum of 1929NHC National Hurricane CenterNOAA National Oceanic and Atmospheric AdministrationUSGS U.S. Geological Survey


By Christopher E. Schubert,1 Ronald Busciolano,1 Paul P. Hearn, Jr.,1 Ami N. Rahav,2 Riley Behrens,1 Jason Finkelstein,1 Jack Monti, Jr.,1 and Amy E. Simonson1

1U.S. Geological Survey

2Harris IT Contracting3Bold text is defined in the glossary.

AbstractThe hybrid cyclone-noreaster3 known as Hurricane

Sandy affected the mid-Atlantic and northeastern United States during October 2830, 2012, causing extensive coastal flood-ing. Prior to storm landfall, the U.S. Geological Survey (USGS) deployed a temporary monitoring network from Virginia to Maine to record the storm tide and coastal flooding generated by Hurricane Sandy. This sensor network augmented USGS and National Oceanic and Atmospheric Administration (NOAA) networks of permanent monitoring sites that also documented storm surge. Continuous data from these networks were sup-plemented by an extensive post-storm high-water-mark (HWM) flagging and surveying campaign. The sensor deployment and HWM campaign were conducted under a directed mission assignment by the Federal Emergency Management Agency (FEMA). The need for hydrologic interpretation of monitoring data to assist in flood-damage analysis and future flood mitiga-tion prompted the current analysis of Hurricane Sandy by the USGS under this FEMA mission assignment.

The analysis of storm-tide impacts focused on three distinct but related aspects of coastal flooding from Hur-ricane Sandy, including flooding inland along the tidal reach of the Hudson River. These aspects are (1) comparisons of peak storm-tide elevations to those of historical storms and to annual exceedance probabilities, (2) assessments of storm-surge characteristics, and (3) comparisons of maps of inundation extent that were derived from differing amounts of available storm-tide data. Most peak storm-tide elevations from Hurricane Sandy were greater than about 9.5 feet (ft) above North American Vertical Datum of 1988.

Peak storm-tide elevations from Hurricane Sandy were compared with data for the intense noreaster of December 1113, 1992, and Hurricane Irene (August 2728, 2011), which weakened to a tropical storm before arriving in New York. Peak storm-tide elevations from Hurricane Sandy were higher than those from the December 1992 noreaster at 24 of 27 sites; most differences were greater than about 0.7 ft

or 9 percent (above the historical storm tide). Peak storm-tide elevations from Hurricane Sandy were higher than those from Tropical Storm Irene at all sites; most differences were greater than about 2.5 ft or 48 percent. Data from permanent and temporary monitoring sites and HWM sites were compared with corresponding FEMA flood elevations for the 10-, 2-, 1-, and 0.2-percent annual exceedance probabilities in New York. Peak storm-tide elevations from Hurricane Sandy had annual exceedance probabilities less than or equal to 1 percent and (or) greater than 0.2 percent at a plurality of sites184 of 413. Peak storm-tide elevations greater than or equal to the 0.2-percent flood elevation accounted for 81 of 413 sites. Peak storm-tide elevations less than the 10-percent flood elevation accounted for only 10 of 413 sites.

Data from selected permanent monitoring sites in the USGS and NOAA networks were used to assess storm-surge magnitude associated with the peak storm tide, and magni-tude and timing of the peak storm surge. Most magnitudes of the peak storm surge were greater than about 8.3 ft, and most magnitudes of the storm surge component of the peak storm tide were greater than about 7.8 ft. Timing of peak storm surge arrival with respect to local phase of tide controlled where the most extreme peak storm-tide levels and coastal flood-ing occurred. This finding has bearing not only for locations impacted by the highest storm tides from Hurricane Sandy, but also for those that had the greatest storm surges yet were spared the worst flooding because of fortuitous timing during this storm.

Results of FEMA Hazus Program (HAZUS) flood loss analyses performed for New York counties were compared for extents of storm-tide inundation from Hurricane Sandy mapped (1) pre-storm, (2) on November 11, 2012, and (3) on February 14, 2013. The resulting depictions of estimated total building stock losses document how differing amounts of avail-able USGS data affect the resolution and accuracy of storm-tide inundation extents. Using the most accurate results from the final (February 14, 2013) inundation extent, estimated losses range from $380 million to $5.9 billion for individual New York counties; total estimated aggregate losses are about $23 billion for all New York counties. Quality of the inundation extents used in HAZUS analyses has a substantial effect on final results. These findings can be used to inform future post-storm recon-struction planning and estimation of insurance claims.

Introduction 32 Analysis of Storm-Tide Impacts From Hurricane Sandy in New York

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Introduction

The hybrid cyclone noreaster known as Hurricane Sandy affected the mid-Atlantic and northeastern coastline of the United States during October 2830, 2012 (fig. 1), producing northeast-to-southeast winds of tropical-storm strength (39 to 73 miles per hour [mi/hr]) that gusted to greater than hurricane strength (greater than 73 mi/hr) and causing extensive coastal flooding and beach erosion. Severe tidal flooding occurred along coastal areas of southeastern New York, northern New Jersey, and southern Connecticut during the afternoon of October 29 and continued through the early morning of October 30. Although peak storm-tide levels occurred near the times of normal tidal high water during October 2930, widespread tidal flooding that began during the morning of October 29 did not subside in some coastal areas until October 31.

Prior to storm landfall, the U.S. Geological Survey (USGS) deployed a temporary monitoring network of water-level and barometric pressure sensors to continuously record the timing, areal extent, and magnitude of the storm tide and coastal flooding generated by Hurricane Sandy (McCallum and others, 2013). Sensors were deployed at 224 locations along the Atlantic coast from Virginia to Maine, including 59 in New York alone (fig. 2). The temporary monitoring network augmented USGS and National Oceanic and Atmo-spheric Administration (NOAA) networks of permanent moni-toring sites (fig. 2) that also documented storm surgethe difference (when positive) between the observed water level and the normal (predicted astronomical) tide level. Continu-ous data from these networks were greatly supplemented by an extensive post-storm high-water-mark (HWM) flagging and surveying campaign from November to December 2012. More than 950 HWMs were measured along the mid-Atlantic and northeastern coastline; roughly one-third of these were mea-sured in southeastern New York and north along the Hudson River to the head-of-tide at the Federal Dam in Troy (fig. 2).

The temporary monitoring network deployment and HWM flagging and surveying campaign were undertaken as part of a coordinated Federal emergency response as out-lined by the Stafford Act (Robert T. Stafford Disaster Relief and Emergency Management Act, Public Law 93288, as amended, 42 U.S.C. 5121 et seq.) under a directed mission assignment by the Federal Emergency Management Agency (FEMA). The methods and data associated with these activi-ties are described in a rapid-delivery report that provides a quantitative historical record of Hurricane Sandy (McCallum and others, 2013). The need for hydrologic interpretation of monitoring data to assist in the analysis of flood damages and future flood-mitigation efforts in New York prompted the cur-rent analysis of Hurricane Sandy under this mission assign-ment with FEMA. This interpretation was conducted by the USGS in cooperation with FEMA.

Purpose and Scope

This report presents the results of an analysis of storm-tide impacts from Hurricane Sandy in New York that was done as part of the FEMA mission assignment. Specifically, the report presents (1) comparisons of peak storm-tide elevations to selected historical storms and annual exceedance probabili-ties; (2) the storm-surge magnitude associated with the peak storm tide, and magnitude and timing of the peak storm surge; and (3) comparisons of selected maps of inundation extent that were derived from differing amounts of available sensor and HWM data.

Meteorological History of Hurricane Sandy

Hurricane Sandy was the 18th named storm and 10th hur-ricane of the 2012 Atlantic hurricane season. Sandy developed from a low pressure system in the Caribbean Sea. Hurricane Sandy was first classified by the National Hurricane Center (NHC) as a tropical depression and then as a tropical storm south of the island of Jamaica on October 22, 2012. After drifting slowly southwest on October 23, on October 24 Sandy turned to the north and intensified into a Category 1 hurricane on the Saffir-Simpson hurricane scale (National Hurricane Center, 2013b) just before making landfall in Jamaica.

Hurricane Sandy continued to the north, intensified into a strong Category 2 hurricane before making landfall in Cuba, and then emerged on the north side of Cuba during the morn-ing of October 25. The storm proceeded to drift northwest as a Category 1 or 2 hurricane as it moved through the Bahamas on October 25 and 26. Hurricane Sandy then began a north-north-east track on October 26 as a Category 1 hurricane (fig. 1). This track continued into the evening of October 28, when Hurricane Sandy turned to the north. Sandy turned northwest on October 29. Hurricane Sandy made landfall near Atlantic City, New Jersey, as an extratropical cyclone at 7:30 p.m. eastern daylight time on October 29 with a minimum central pressure of 945 millibars. The storm moved inland over New Jersey and weakened into a remnant trough in western Penn-sylvania on October 31.

The unusual north-to-northwest motion of the storm that began on October 28 was caused by two factors: (1) an anom-alously strong, blocking high-pressure system situated over the Canadian Maritimes and (2) an approaching and deepening midlatitude trough to the west over the eastern United States. These factors caused the storm to curve toward the coast south of New York City and Long Island. Hurricane Sandys interac-tion with these two weather systems also caused the storms transition from a tropical to a post-tropical system, which cre-ated an outward expansion of the storms wind field. Just prior to United States landfall, this wind field or fetch was estimated to be about 1,000 miles (mi) wide (fig. 3), making Sandy the largest Atlantic Hurricane on record (Blake and others, 2013).

The extremely large fetch of tropical-storm force winds circulating around Hurricane Sandy, combined with its

Introduction 54 Analysis of Storm-Tide Impacts From Hurricane Sandy in New York

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NTIC

OCE

AN

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n g

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a n

d S

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n d

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n g

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a n

d

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son

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r

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73W

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41

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40

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enl

arge

d on

faci

ng p

age.

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73W

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42N

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from

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iona

l Oce

anic

and

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osph

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inis

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solu

tion

1:70

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le d

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l vec

tor s

hore

line

data

, 199

4 Un

iver

sal T

rans

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e M

erca

tor,

zone

18N

pro

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ion

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re 2

. Lo

catio

ns o

f per

man

ent a

nd te

mpo

rary

mon

itorin

g si

tes

and

high

-wat

er-m

ark

site

s th

at d

ocum

ente

d th

e st

orm

tide

of H

urric

ane

Sand

y in

New

Yor

k co

untie

s. In

set

show

s en

larg

emen

t of t

he fi

ve c

ount

ies

that

com

pris

e N

ew Y

ork

City

Br

onx,

Kin

gs, N

ew Y

ork,

Que

ens,

and

Ric

hmon

d.

Wind speed, in miles per hour

60

50

40

30

20

10

0

EXPLANATION45

42.5

40

37.5

35

32.5

30

27.5

25-77.5-80 -75 -72.5 -70 -67.5 -65 -62.5 -60

Longitude

Latit

ude

Analysis of Storm-Tide Impacts From Hurricane Sandy 76 Analysis of Storm-Tide Impacts From Hurricane Sandy in New York

anomalous track, piled large amounts of ocean water over multiple tidal cycles north and west of the center of counter-clockwise circulation. This onshore flow was funneled into the New York Bightthe large embayment formed by the Atlantic coastline of Long Island and northern New Jerseyand inland through the many interconnected estuaries, propagating more than 100 mi north along the Hudson River to the head-of-tide at the Federal Dam in Troy. These are the primary reasons why Hurricane Sandy caused historic coastal flooding in these areas, producing a storm surge much greater than that expected for a Category 1 hurricane taking a more normal north-to-northeast track up the Atlantic seaboard.

Winds in the southeastern New York region began to increase well in advance of Hurricane Sandy. By the afternoon of October 27, as Hurricane Sandy was moving northeast along the southeastern United States coast, winds in the region began to increase from an east to northeast direction. This was primarily due to the pressure gradient between the hurricane

well to the south and the blocking high to the northeast of the region. As the storm approached Cape Hatteras, North Carolina, on the afternoon of October 28, winds began to shift to a more northeast direction; winds shifted to the north-northeast by the end of the day, as the hurricane continued moving northeastward well east of Cape Hatteras. During the day on October 29, the storm began its sharp turn towards the southern New Jersey coast and transitioned to a post-tropical system with winds rapidly increasing over the region and shifting back to the northeast. Maximum winds occurred from late in the afternoon to around midnight on October 29. As the storm approached and then made landfall south of the region, the strong winds quickly switched to an easterly direction by late afternoon and then to a southeasterly direction just after landfall. As the storm continued moving inland through southern New Jersey and then into Pennsylvania, strong winds from the southeast to south continued for a few hours and then gradually decreased during the day on October 30.

Analysis of Storm-Tide Impacts From Hurricane Sandy

The analysis of storm-tide impacts focused on three distinct but related aspects of coastal flooding produced by Hurricane Sandy(1) comparisons of peak storm-tide eleva-tions to historical storms and annual exceedance probabilities, (2) identification of the storm-surge magnitude associated with the peak storm tide, and magnitude and timing of the peak storm surge, and (3) comparisons of selected maps of inunda-tion extent that were derived from differing amounts of avail-able sensor and HWM data.

Peak Storm-Tide Elevation

Peak storm-tide elevations at the permanent and temporary monitoring sites and HWM sites shown in figure 4 provide a comprehensive depiction of the coastal flooding from Hurricane Sandy in New York. The data for these sites are also available from a USGS interactive storm-tide mapper at http://water.usgs.gov/floods/events/2012/sandy/sandymapper.html. The storm-tide elevations have been affected by wave action to varying degrees, depending on the measurement techniques and site conditions under which the data were collected. A diagram of FEMA coastal flood hazard zones and the manner in which wave heights affect base flood elevations (BFEs), particularly at locations in VE zones (Federal Emergency Management Agency, 2013a) is shown in figure 5. Specifically, these loca-tions are likely to have flooding with wave heights of 3 feet (ft) or greater, whereas those in AE zones will have flooding with wave heights less than 3 ft.

As a result, records from permanent and temporary monitoring sites in VE zones likely were affected by wave heights of 3 ft or greater, the effects of which were removed using a 3-minute mean to obtain a peak elevation comparable with stillwater elevations; monitoring records from sites in other coastal flood hazard zones likely were affected by wave heights less than 3 ft and, thus, provide a peak elevation gener-ally comparable with the corresponding stillwater elevations. Similarly, HWMs at sites in VE zones likely were affected by wave heights of 3 ft or greater and, therefore, are comparable only with the BFEs. HWMs at sites in other coastal flood hazard zones likely were affected by wave heights less than 3 ft and, thus, are generally comparable with the corresponding stillwater elevations.

Most peak storm-tide elevations from Hurricane Sandy (fig. 4) were greater than about 9.5 ft above North American Vertical Datum of 1988 (NAVD 88); this level was exceeded at most of the sites in Albany, Nassau, Rensselaer, and Westchester Counties and New York City (Bronx, Kings, New York, Queens, and Richmond Counties). In the remain-ing counties with Hurricane Sandy dataDutchess, Greene, Orange, Rockland, Suffolk, and Ulster, peak storm-tide elevations were greater than about 7.2 ft above NAVD 88

at most sites. The maximum peak storm-tide elevation was 16.9 ft above NAVD 88 at HWM site HWMNYRIC717 (map number 230) in New York City. The minimum peak storm-tide elevation was 3.5 ft above NAVD 88 at HWM site HWMNYSUF638 (map number 373) in Suffolk County. Data were not obtained along the east shore of the Hudson River in Columbia and Putnam counties; HWMs obtained along the west shore in Greene and Orange counties represent peak storm-tide elevations in these reaches.

Comparison With Historical StormsPeak storm-tide elevations produced by Hurricane Sandy

were compared with those of historical storms for which data on substantial coastal flooding are available. These storms include the intense noreaster of December 1113, 1992, and Hurricane Irene (August 2728, 2011), which weakened to a tropical storm before arriving in New York.

December 1992 Noreaster

The intense noreaster that affected the mid-Atlantic and northeastern coastline of the United States during December 1014, 1992 (fig. 1), produced east-to-northeast winds of gale-force strength (39 to 54 mi/hr) that gusted to greater than hurricane strength and caused heavy rain, extensive coastal flooding, and severe beach erosion (Schubert and Bus-ciolano, 1994). Severe tidal flooding occurred during the morn-ing of December 11 and continued through the early afternoon of December 12 along coastal areas of southeastern New York, northern New Jersey, and southern Connecticut. Although peak storm-tide levels occurred near the times of normal tidal high water during December 1112, widespread tidal flooding did not subside in many coastal areas until December 14.

Peak storm-tide elevations produced by the storm of December 1113, 1992, at 27 HWM sites and peak storm-tide elevations produced by Hurricane Sandy at nearby sites in New York are listed in table 1. Calculations of the differ-ences between their peak storm-tide elevations are included in table 1, and the differences are depicted in units of feet and percent (above the historical storm tide) in figure 6A and 6B, respectively. These differences indicate that peak storm-tide elevations from Hurricane Sandy were higher than those from the December 1992 noreaster at 24 of 27 sites (89 percent). Most differences were greater than about 0.7 ft or 9 percent, with most of these from sites along the Atlantic Ocean shores of Nassau and Suffolk Counties and New York City. The maxi-mum absolute difference was 4.5 ft at HWM site HWMNYQUE505 (Hunters Point) in New York City, and the maximum relative difference was 110 percent at HWM sites HWMNYSUF407 (Bay Shore), HWMNYSUF600 (Oakdale), and HWMNYSUF620 (Bellport) along the Atlantic Ocean shore of Suffolk County. The minimum absolute and relative differ-ences were 0.5 ft and 4 percent, respectively, at HWM site HWMNYNAS936 (Bayville) along the Long Island Sound shore of Nassau County.

Figure 3. Strength and direction of Hurricane Sandys ocean surface winds on October 28, 2012. Wind speeds above 40 miles per hour are depicted in yellow, above 50 are in orange, and above 60 are in red; wind directions are indicated by black arrows. Map is modified from National Aeronautics and Space Administration (2013) produced with data from a radar scatterometer on the Indian Space Research Organizations Oceansat-2.

http://water.usgs.gov/floods/events/2012/sandy/sandymapper.htmlhttp://water.usgs.gov/floods/events/2012/sandy/sandymapper.html


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zone

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re 4

. Pe

ak s

torm

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vatio

ns p

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by H

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y in

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Yor

k co

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nd R

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ond.


Tabl

e 1.

Pe

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torm

-tide

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vatio

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by s

torm

of D

ecem

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113

, 199

2, a

t 27

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are

show

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figu

re 2

. GM

T, G

renw

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n Ti

me;

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8, N

orth

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of 1

988]

Hur

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11

Figure 5. Federal Emergency Management Agency coastal flood hazard zones and effects of wave heights on base flood elevations (BFEs), particularly at locations in the VE zone; from Federal Emergency Management Agency, 2013a. VE zone is the area subject to high velocity wave action (a 3-foot breaking wave) from the 1-percent annual chance coastal flood. AE zone is the area subject to inundation from the 1-percent annual chance flood; these areas are not subject to high velocity wave action but are still considered high risk flooding areas. X zone is the area of moderate coastal flood risk outside the regulatory 1-percent annual chance flood up to the 0.2-percent annual chance flood level. LiMWA, limit of moderate wave action; NFIP, National Flood Insurance Program; SFHA, special flood hazard area.


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data

, 199

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zone

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ject

ion

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re 6

. A,

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eren

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in fe

et b

etw

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peak

sto

rm-ti

de e

leva

tions

pro

duce

d by

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rican

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ndy

and

the

stor

m o

f Dec

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r 11

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992,

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ork.

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rgem

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five

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ntie

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at c

ompr

ise

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k Ci

ty

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x, K

ings

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k, Q

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nd R

ichm

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EE

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D

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ER

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River

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son

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40

30'N

Area

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age

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40

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sal T

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tor,

zone

18N

pro

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ion

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re 6

. B,

Diff

eren

ces

in p

erce

nt b

etw

een

peak

sto

rm-ti

de e

leva

tions

pro

duce

d by

Hur

rican

e Sa

ndy

and

the

stor

m o

f Dec

embe

r 11

13, 1

992,

in N

ew Y

ork.

Inse

t sho

ws

enla

rgem

ent o

f the

five

cou

ntie

s th

at c

ompr

ise

New

Yor

k Ci

ty

Bron

x, K

ings

, New

Yor

k, Q

ueen

s, a

nd R

ichm

ond.

Co

ntin

ued.


Tabl

e 2.

Pe

ak s

torm

-tide

ele

vatio

ns p

rodu

ced

by H

urric

ane

Sand

y, T

ropi

cal S

torm

Iren

e, a

nd h

isto

rical

pea

k w

ater

-leve

l ele

vatio

ns, d

ates

of o

ccur

renc

e, a

nd p

erio

ds o

f rec

ord

at 1

9 pe

rman

ent m

onito

ring

site

s in

New

Yor

k.

[Per

man

ent m

onito

ring

site

loca

tions

are

show

n in

figu

re 2

. Pea

k st

orm

-tide

reco

rds f

or T

ropi

cal S

torm

Iren

e at

Nat

iona

l Oce

anic

and

Atm

osph

eric

Adm

inis

tratio

n (N

OA

A) s

ites f

rom

Fan

elli

and

Fane

lli, 2

011;

re

cord

s for

Hur

rican

e Sa

ndy

at N

OA

A si

tes f

rom

Fan

elli

and

othe

rs, 2

013.

His

toric

al p

eak

wat

er-le

vel r

ecor

ds a

nd p

erio

ds o

f rec

ord

at N

OA

A si

tes f

rom

Nat

iona

l Oce

an S

ervi

ce, 2

013.

GM

T, G

renw

ich

Mea

n Ti

me;

NAV

D 8

8, N

orth

Am

eric

an V

ertic

al D

atum

of 1

988]

Hur

rica

ne S

andy

Trop

ical

Sto

rm Ir

ene

peak

st

orm

tide

Diff

eren

ce in

pea

k st

orm

-tid

e el

evat

ion

His

tori

cal p

eak

wat

er le

vel

Peri

od o

f rec

ord

Site

Peak

sto

rm ti

de

Map

no

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entif

ier

Latit

ude,

in

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imal

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gree

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Long

itude

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dec

imal

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gree

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ated

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te

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T)

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atio

n,

in fe

et

abov

e N

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88

Estim

ated

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te

(GM

T)

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atio

n,

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et

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e N

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88

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Perc

ent

Estim

ated

da

te

Elev

atio

n, in

fe

et a

bove

N

AVD

88

Dutc

hess

Cou

nty

601

3720

5841

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458

10/3

0/20

128.

668/

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1.58

228/

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011

7.08

1992

201

3N

assa

u Co

unty

2701

3022

5040

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22-7

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019

10/3

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.31

8/28

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18.

391.

9223

3/15

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08.

5020

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013

2801

3026

0040

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56-7

3.63

800

10/3

0/20

129.

878/

28/2

011

8.21

1.66

208/

28/2

011

8.21

2009

201

329

0130

2845

40.9

0511

-73.

5931

910

/30/

2012

10.0

68/

28/2

011

8.04

2.02

258/

28/2

011

8.04

2007

201

360

1,2 0

1303

000

40.8

8750

-73.

5636

110

/30/

2012

10.2

8/28

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18.

41.

821

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810

.26

1937

200

0, 2

005

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500

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5722

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4633

310

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2012

9.7

8/28

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19.

140.

67

8/31

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49.

6719

502

013

3001

3105

2140

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60-7

3.57

541

10/3

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128.

988/

28/2

011

6.22

2.76

448/

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6.22

1999

201

331

0131

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40.5

9344

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5837

410

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2012

8.97

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15.

943.

0351

8/28

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15.

9419

972

013

3201

3111

4340

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83-7

3.65

611

10/3

0/20

129.

778/

28/2

011

6.63

3.14

478/

28/2

011

6.63

2010

201

333

0131

1145

40.5

9316

-73.

7373

510

/30/

2012

9.70

8/28

/201

16.

333.

3753

8/28

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16.

3320

022

013

3501

3118

5040

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33-7

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791

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1210

.55

8/28

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16.

424.

1364

8/28

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16.

4220

022

013

New

Yor

k Ci

ty11

001

3020

5040

.755

83-7

3.74

583

10/3

0/20

129.

698/

28/2

011

9.46

0.23

210

/19/

1996

10.3

519

932

013

111

0131

1875

40.5

7372

-73.

8851

410

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2012

10.6

58/

28/2

011

6.48

4.17

648/

28/2

011

6.48

2002

201

311

485

1875

0N

OA

A40

.700

00-7

4.01

333

10/3

0/20

1211

.28

8/28

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16.

724.

5668

12/1

1/19

926.

9319

202

013

Oran

ge C

ount

y24

14 0

1374

019

41.3

8620

-73.

9551

010

/30/

2012

8.6

8/28

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16.

691.

928

8/28

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16.

6919

912

013

Rock

land

Cou

nty

250

5 013

7626

941

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19-7

3.89

610

10/3

0/20

129.

78/

28/2

011

6.56

3.1

478/

28/2

011

6.56

2010

201

3Su

ffolk

Cou

nty

251

0130

4057

40.9

6286

-73.

1431

710

/30/

2012

9.35

8/28

/201

17.

811.

5420

8/28

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17.

8120

072

013

255

0130

9225

40.6

6927

-73.

3556

810

/30/

2012

6.54

8/28

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14.

082.

4660

8/28

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14.

0820

022

013

256

8510

560

NO

AA

41.0

4833

-71.

9600

010

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2012

5.55

8/28

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14.

081.

4736

8/31

/195

46.

8719

472

013

1 Per

man

ent m

onito

ring

site

0130

3000

was

disc

ontin

ued

in F

ebru

ary

2011

; pea

k el

evat

ion

for H

urric

ane

Sand

y us

es v

alue

from

hig

h-w

ater

-mar

k sit

e H

WM

NY

NA

S70

0 at

sam

e lo

catio

n.2 P

erm

anen

t mon

itorin

g sit

e 01

3030

00 w

as d

iscon

tinue

d in

Feb

ruar

y 20

11; p

eak

elev

atio

n fo

r Tro

pica

l Sto

rm Ir

ene

uses

val

ue fr

om h

igh-

wat

er-m

ark

site

HW

MN

YN

AS

003

at sa

me

loca

tion.

3 Mea

sure

men

t lim

it at

per

man

ent m

onito

ring

site

0130

3500

was

exc

eede

d du

ring

Hur

rican

e Sa

ndy;

pea

k el

evat

ion

for t

his s

torm

use

s val

ue fr

om h

igh-

wat

er-m

ark

site

HW

MN

YN

AS

923

at sa

me

loca

tion.

4 Mea

sure

men

t lim

it at

per

man

ent m

onito

ring

site

0137

4019

was

exc

eede

d du

ring

Hur

rican

e Sa

ndy;

pea

k el

evat

ion

for t

his s

torm

use

s val

ue fr

om h

igh-

wat

er-m

ark

site

HW

MN

YO

RA0

04 a

t sam

e lo

catio

n.5 M

easu

rem

ent l

imit

at p

erm

anen

t mon

itorin

g sit

e 01

3762

69 w

as e

xcee

ded

durin

g H

urric

ane

Sand

y; p

eak

elev

atio

n fo

r thi

s sto

rm u

ses v

alue

from

hig

h-w

ater

-mar

k sit

e H

WM

NY

RO

C00

6 at

sam

e lo

catio

n.

Tropical Storm Irene

Tropical Storm Irene initially made landfall as a Cat-egory 1 hurricane on the North Carolina coast near Beaufort on August 27, 2011 (fig. 1); after traversing the coast and Outer Banks of North Carolina, the storm went back out to sea and made a second landfall as a Category 1 hurricane near Atlantic City, New Jersey, on August 28 (McCallum and oth-ers, 2012). The resulting storm tide reached National Weather Service moderate to major flood thresholds in coastal areas of Long Island and New York City as Irene crossed western Long Island on August 28 as a tropical storm (Busciolano and Schubert, 2012).

Peak storm-tide elevations produced by Hurricane Sandy and Tropical Storm Irene at 19 permanent monitoring sites, 23 temporary monitoring sites, and 10 HWM sites in New York are given in tables 2, 3, and 4, respectively. The data in tables 2 through 4 include the differences between their peak storm-tide elevations for the two storms; differ-ences in elevations are depicted in units of feet and percent in figure 7A and 7B, respectively. These differences indicate that peak storm-tide elevations from Hurricane Sandy were higher than those from Tropical Storm Irene at all sites. Most differences were greater than about 2.5 ft or 48 percent, with most of these from sites along the Atlantic Ocean shores of Nassau and Suffolk Counties, in New York City, and in Rock-land County. The maximum absolute difference was 6.5 ft at HWM site HWMNYRIC719 (005CNY01006) in New York City (table 4), and the maximum relative difference was 111 percent at HWM site HWMNYKIN908 (005CNY02003), also in New York City. The minimum absolute and relative differences were 0.14 ft and 1.7 percent, respectively, at temporary monitoring site SSSNYSUF002WL (table 3) along the Long Island Sound shore of Suffolk County.

Historical Peak Water-Level Elevations

Peak storm-tide elevations produced by Hurricane Sandy, historical peak water-level elevations, estimated dates of occur-rence, and periods of record at 19 permanent monitoring sites in New York are presented in table 2. Of the 19 permanent monitoring sites, the peak storm-tide elevation from Hurricane Sandy exceeded the historical peak water-level elevation at 16 sites (84 percent) and was very close to the historical peak at 1 site (5 percent). One of the two sites where the historical peak was greater than the peak from Hurricane SandyUSGS site 01302050is a streamgage in New York City that histori-cally may have been affected by high streamflow. The other siteNOAA site 8510560is a tide gage in Suffolk County near the extreme eastern tip of Long Island, where the storm-tide impacts from Hurricane Sandy were less than those at sites farther westward. The one site where the peak from Hurricane Sandy was very close to, but did not exceed, the historical peakUSGS streamgage 01303000is along the Long Island Sound shore of Nassau County. This historical peak is from the unnamed, major hurricane of September 21, 1938; however, it was only 0.06 ft higher than the peak from Hurricane Sandy.

Comparison With Annual Exceedance Probabilities

Peak storm-tide elevations at the permanent and tempo-rary monitoring sites and the HWM sites were compared with the corresponding FEMA flood elevations for the 10-, 2-, 1-, and 0.2-percent annual exceedance probabilities (10-, 50-, 100-, and 500-year recurrence intervals). The comparison relied on stillwater flood elevations, and on coastal flood hazard zones and base flood elevations, which were generally derived from the most recently published FEMA Flood Insurance Study (FIS) and Flood Insurance Rate Map (FIRM) products, respectively, that were in effect for New York localities affected by the storm tide of Hurricane Sandy. One exception to this was in New York City, where the comparison relied primarily on coastal flood hazard zones and flood elevations derived from preliminary work map data (Federal Emergency Management Agency, 2013e), which represent the best available information at the time of this study. A comparison of peak storm-tide elevations to annual exceedance probabilities for New York City was also performed using the most recently published FEMA FIS and FIRM products for this locality; the data are listed in tables 5 through 7. However, this comparison with legacy products is not discussed in the text or shown in the figures.

Peak storm-tide elevations produced by Hurricane Sandy and the corresponding FEMA flood elevations for the 10-, 2-, 1-, and 0.2-percent annual exceedance probabilities (10-, 50-, 100-, and 500-year recurrence intervals) at 24 permanent monitoring sites, 43 temporary monitoring sites, and 346 HWM sites in New York are listed in tables 5, 6, and 7, respectively. The compari-sons between Hurricane Sandy peak storm-tide elevations and FEMA flood elevations for sites in tables 5 through 7 also include the annual exceedance probabilities (and recurrence intervals) for these sites; annual exceedance probabilities are shown in figure 8. These comparisons indicate that peak storm-tide elevations from Hurricane Sandy had annual exceedance probabilities of less than or equal to 1 percent and (or) greater than 0.2 percent (recurrence intervals greater than or equal to 100 years and (or) less than 500 years) at a plurality of sites184 of 413 (45 percent).

Most of the peak storm-tide elevations greater than or equal to the FEMA 1-percent (100-year) flood elevation and (or) less than the 0.2-percent (500-year) flood elevation were from sites in Dutchess, Nassau, Orange, Rockland, Suffolk, and Ulster Coun-ties; New York City; and along the Hudson River shore of West-chester County (fig. 8). Peak storm-tide elevations associated with the minimum annual exceedance probabilities (maximum recurrence intervals)elevations higher than or equal to the FEMA 0.2-percent (500-year) flood elevationaccounted for 81 of 413 sites (20 percent); most of these were along the Atlantic Ocean shores of Nassau and western Suffolk Counties, in Orange and Rockland Counties, and along the Hudson River shore of Westchester County. Peak storm-tide elevations associated with the maximum annual exceedance probability (minimum recur-rence interval)elevations lower than the FEMA 10-percent (10-year) flood elevationaccounted for only 10 of 413 sites (2 percent); most of these were in Albany and Rensselaer Counties.

Analysis of Storm-Tide Impacts From Hurricane Sandy 1918 Analysis of Storm-Tide Impacts From Hurricane Sandy in New YorkTa

ble

3.

Peak

sto

rm-ti

de e

leva

tions

pro

duce

d by

Hur

rican

e Sa

ndy

and

Trop

ical

Sto

rm Ir

ene

at 2

3 te

mpo

rary

mon

itorin

g si

tes

in N

ew Y

ork.

[Tem

pora

ry m

onito

ring

site

loca

tions

are

show

n in

figu

re 2

. GM

T, G

renw

ich

Mea

n Ti

me;

NAV

D 8

8, N

orth

Am

eric

an V

ertic

al D

atum

of 1

988]

Hur

rica

ne S

andy

Trop

ical

Sto

rm Ir

ene

Diff

eren

ce

Site

Peak

sto

rm ti

deSi

tePe

ak s

torm

tide

Site

lo

catio

n,

in m

iles

Peak

sto

rm-t

ide

elev

atio

n

Map

no

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entif

ier

Latit

ude,

in

dec

imal

de

gree

s

Long

itude

, in

dec

imal

de

gree

s

1 Coa

stal

flo

od

haza

rd

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Estim

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te

(GM

T)

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atio

n,

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et

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e

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e,

in d

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al

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ees

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itude

, in

dec

imal

de

gree

s

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flo

od

haza

rd

zone

Estim

ated

da

te

(GM

T)

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atio

n,

in fe

et

abov

e

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D 88

Feet

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ent

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sau

Coun

ty37

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NY

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2012

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NY

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2012

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8/28

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730.

000

3.96

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3 New

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k Ci

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4533

-73.

8363

8V

E8/

28/2

011

6.79

0.00

04.

0560

123

SSS

NY

RIC

001

WL

40.5

9388

-74.

0598

5V

E10

/30/

2012

12.4

3SS

SN

YR

IC0

01W

L40

.593

88-7

4.05

985

VE

8/28

/201

17.

330.

000

5.10

7012

5SS

SN

YR

IC0

03W

L40

.501

88-7

4.23

034

VE

10/3

0/20

1213

.81

SSS

NY

RIC

003

WL

40.5

0188

-74.

2303

4V

E8/

28/2

011

7.35

0.00

06.

4688

4 New

Yor

k Ci

ty11

6SS

SN

YK

IN0

01W

L40

.580

00-7

4.01

161

VE

10/3

0/20

1211

.57

SSS

NY

KIN

001

WL

40.5

8000

-74.

0116

1V

E8/

28/2

011

6.83

0.00

04.

7469

119

SSS

NY

QU

E00

1WL

40.7

6229

-73.

8582

8V

E10

/30/

2012

10.3

2SS

SN

YQ

UE

001W

L40

.762

29-7

3.85

828

VE

8/28

/201

18.

020.

000

2.30

2912

0SS

SN

YQ

UE

002W

L40

.645

33-7

3.83

638

VE

10/3

0/20

1210

.84

SSS

NY

QU

E00

2WL

40.6

4533

-73.

8363

8V

E8/

28/2

011

6.79

0.00

04.

0560

123

SSS

NY

RIC

001

WL

40.5

9388

-74.

0598

5V

E10

/30/

2012

12.4

3SS

SN

YR

IC0

01W

L40

.593

88-7

4.05

985

VE

8/28

/201

17.

330.

000

5.10

7012

5SS

SN

YR

IC0

03W

L40

.501

88-7

4.23

034

VE

10/3

0/20

1213

.81

SSS

NY

RIC

003

WL

40.5

0188

-74.

2303

4V

E8/

28/2

011

7.35

0.00

06.

4688

analysis of storm-tide impacts from hurricane sandy in new york

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