DTIC ADA582932: Modeling of Coastal Inundation, Storm Surge, and Relative Sea-Level Rise at Naval Station Norfolk, Norfolk, Virginia, USA

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JournalofCoastalResearch 29 1 18–30 CoconutCreek,Florida January2013
ModelingofCoastal Inundation,StormSurge,andRelativeSea-
Level Rise at Naval Station Norfolk, Norfolk, Virginia, U.S.A.
Honghai Li†, Lihwa Lin†, and Kelly A. Burks-Copes‡
†U.S.ArmyEngineerResearch&DevelopmentCenter ‡U.S.ArmyEngineerResearch&DevelopmentCenter
CoastalandHydraulicsLaboratory EnvironmentalLaboratory
3909HallsFerryRoad 3909HallsFerryRoad
Vicksburg,MS39180-6199,U.S.A. Vicksburg,MS39180-6199,U.S.A.
[email protected]
ABSTRACT
Li,H.;Lin,L.,andBurks-Copes,K.A.,2013.Modelingofcoastalinundation,stormsurge,andrelativesea-levelriseat
Naval StationNorfolk, Norfolk, Virginia, U.S.A. Journal ofCoastalResearch, 29(1),18–30. Coconut Creek (Florida),
ISSN0749-0208.
Thepotentialriskandeffectsofstorm-surgedamagecausedbythecombinationofhurricane-forcewaves,tides,and
relativesea-level-rise(RSLR)scenarioswereexaminedattheU.S.NavalStation,Norfolk,Virginia.Ahydrodynamicand
sedimenttransportmodelingsystemvalidatedwithmeasuredwaterlevelsfromHurricaneIsabelwasusedtosimulate
two synthesized storms representing 50-year and 100-year return-period hurricanes, a northeaster, and five future
RSLRscenariostoevaluatethecombinedimpactsofinundationonthismilitaryinstallationinthelowerChesapeake
Bay.ThenavalbasetopographyandnearshorewaterbodyofHamptonRoadswereincludedinthecoastalmodeling
system(CMS),asuiteofsurge,circulation,wave,sedimenttransport,andmorphologyevolutionmodels.Themodeling
domainwasarectangularareacoveringtheentireNavalStationNorfolkintheHamptonRoadsandthemouthsofthe
JamesandElizabethrivers.Avariable-resolutiongridsystemwascreatedwithafinerresolutionof10minthenaval
baseandacoarserresolutionof300mintheregionsawayfromthebase.Theboundary-forcingconditionstotheCMS
wereregionalstormsurgeproducedbytheADvancedCIRCulation(ADCIRC),andwaveconditionsbytheSimulating
WAveNearshore(SWAN)model.TheCMScalculatedthelocalwater-surfaceelevationandstorm-surgeinundationfor
combinedRSLR,surge,waves,andwind.Resultsindicatethatsyntheticstormswouldcauseextensiveinundationof
coastallandaroundthenavalbase.Approximately60%ofthelandwouldbeunderwaterwiththe100-yearstormforthe
presentsealevel,and80%forestimatedRSLRof2m.
ADDITIONAL INDEX WORDS: Nearshore hydrodynamic modeling, waves, synthetic tropical storms, extratropical
storms,HurricaneIsabel,landflooding.
INTRODUCTION provide decision makers with relevant guidance regarding
existingandfuturecoastalinfrastructuredevelopment.
Globalsea-levelrise(SLR)rangingfrom0.5to2mhasbeen
Militarycoastalinstallationsandfacilitiessupportarangeof
predictedoverthenextcentury,from2000to2100(IPCC,2007;
activities vital to national security and provide significant
Pfeffer,Harper,andO’Neel,2008).RelativeSLR(RSLR)canbe
benefitstothelocaleconomy.Thesefacilitiescarryoutdiverse
greaterthanthe global trendbecauseoflocaleffectssuch as
subsidence.ThecombinationofanincreaseinSLRandcoastal tasksfromoutdoortrainingactivities(ground,ports,harbors,
storms, including hurricanes (tropical storms) and winter andnavigation) toaircombat.The NavalStationNorfolk, in
storms(extratropicalstorms),willincreasetheriskofstorm- Norfolk, Virginia, was selected as a demonstration site for a
surgeinundationinexposedcoastalregions. Onaverage,1.6 risk-assessmentstudytounderstandtheeffectsofRSLRand
hurricanesperyearinthelastcenturyhavemadelandfallon coastalstormsonthephysicalinstallationaswellasnearshore
the U.S. coastline (Smith, 1999). For the East Coast of the physical processes. The coastal modeling system (CMS) was
United States, Hirsch, DeGaetano, and Colucci (2001) devel- applied to calculate the inundation and navigation channel
oped a climatology of winter storms based on historical data shoaling for various future RSLR scenarios. Herein, we
andestimatedanaverageof12stormsforeachwinterseason. describe the implications of potential RSLR estimates and
Sea-levelrisecombinedwithstrongstormswillworsenbeach
storm surges on total inundation; a subsequent paper will
erosion,increasedamagetocoastalinfrastructure,andcause
discussresultsrelatingtosedimenttransportandnavigation
majorshorelinechange(McLeanetal.,2001).Itisessentialto
channelshoaling.
quantify the risk associated with SLR and storm damage to
METHODOLOGY
DOI: 10.2112/JCOASTRES-D-12-00056.1 received 17 March 2012;
acceptedinrevision17June2012.
The CMS is an integrated suite of numerical models for
PublishedPre-printonline17September2012.
(cid:2)CoastalEducation&ResearchFoundation2013 simulatingwater-surfaceelevation,current,waves,sediment
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1. REPORT DATE 2. REPORT TYPE 3. DATES COVERED
JAN 2013 N/A -
4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER
Modeling of Coastal Inundation, Storm Surge, and Relative Sea-Level
5b. GRANT NUMBER
Rise at Naval Station Norfolk, Norfolk, Virginia, USA
5c. PROGRAM ELEMENT NUMBER
6. AUTHOR(S) 5d. PROJECT NUMBER
Li, Honghai; Lin, Lihwa; Burks-Copes, Kelly A.
5e. TASK NUMBER
5f. WORK UNIT NUMBER
7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION
US Army Engineer Research and Development Center, Coastal and REPORT NUMBER
Hydraulics Laboratory, Vicksburg, MS; US Army Engineer Research
and Development Center, Environmental Laboratory, Vicksburg, MS
9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR’S ACRONYM(S)
11. SPONSOR/MONITOR’S REPORT
NUMBER(S)
12. DISTRIBUTION/AVAILABILITY STATEMENT
Approved for public release, distribution unlimited
13. SUPPLEMENTARY NOTES
The original document contains color images.
14. ABSTRACT
The potential risk and effects of storm-surge damage caused by the combination of hurricane-force waves,
tides, and relative sea-level-rise (RSLR) scenarios were examined at the U.S. Naval Station, Norfolk,
Virginia. A hydrodynamic and sediment transport modeling system validated with measured water levels
from Hurricane Isabel was used to simulate two synthesized storms representing 50-year and 100-year
return-period hurricanes, a northeaster, and five future RSLR scenarios to evaluate the combined impacts
of inundation on this military installation in the lower Chesapeake Bay. The naval base topography and
nearshore water body of Hampton Roads were included in the coastal modeling system (CMS), a suite of
surge, circulation, wave, sediment transport, and morphology evolution models. The modeling domain was
a rectangular area covering the entire Naval Station Norfolk in the Hampton Roads and the mouths of the
James and Elizabeth rivers. A variable-resolution grid system was created with a finer resolution of 10 m
in the naval base and a coarser resolution of 300 m in the regions away from the base. The
boundary-forcing conditions to the CMS were regional storm surge produced by the ADvanced
CIRCulation (ADCIRC),and wave conditions by the Simulating WAve Nearshore (SWAN) model. The
CMS calculated the local water-surface elevation and storm-surge inundation for combined RSLR, surge,
waves, and wind. Results indicate that synthetic storms would cause extensive inundation of coastal land
around the naval base. Approximately 60% of the land would be under water with the 100-year storm for
the present sea level, and 80% for estimated RSLR of 2 m.
15. SUBJECT TERMS
16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF 18. NUMBER 19a. NAME OF
ABSTRACT OF PAGES RESPONSIBLE PERSON

a. REPORT b. ABSTRACT c. THIS PAGE UU 13
unclassified unclassified unclassified
Standard Form 298 (Rev. 8-98)
Prescribed by ANSI Std Z39-18
ModelingofCoastalInundationatNavalStationNorfolk,Virginia,U.S.A. 19
transport, and morphology change in coastal and inlet
applications. It consists of a hydrodynamic and sediment
transport model, CMS-Flow, and a spectral wave model,
CMS-Wave,andcanbecoupledwithaparticle-trackingmodel.
Thecoupledmodelingsystemcalculatestime-dependentwater
elevation,currentspeedanddirection,sedimenttransportflux,
andbottomandlandsurfaceerosionandaccretion.
CMS-Flow is a two-dimensional (2-D) finite-volume model
thatsolvesthemassconservationandshallow-watermomen-
tumequationsofwatermotiononanonuniformCartesiangrid
(Buttolphetal.,2006;Sanchezetal.,2011a,b).Waveradiation
stresses and wave parameters are calculated by CMS-Wave
andsuppliedtoCMS-Flowfortheflowandsedimenttransport
calculations.Water-level,current,andmorphologychangesare
providedtoCMS-Waveatuser-specifiedintervals,whichis3
hoursinthisapplication.
CMS-Waveisa2-Dspectralwavetransformationmodelthat
solves the steady-state wave-action balance equation on a
nonuniformCartesiangrid(Linetal.,2008,2011).Themodelis
designed to simulate wave processes that are significant in Figure1. TheCMSoperationalflowchart.
coastal inlets, inthe nearshorezone,inthe vicinity ofjetties
and breakwaters, and in ports and harbors. These processes
includewaveshoaling,refraction,diffraction,reflection,wave
[NOAA] gauge 8638610) was 4.4 mm/y, which is far greater
breaking and dissipation, wave-structure and wave-current
than the global trend of 2.4 mm/y (Jevrejeva et al., 2006;
interactions, and wave generation and growth mechanisms.
NOAA, 2012). Thus, if there is no acceleration in the global
Themodelmaybeusedinhalf-planeorfull-planemode,with
trend,RSLRatSewellsPointwouldbe0.44min100years.The
waves propagating primarily from open boundaries into the
RSLRscenariosappliedinthisstudywereintendedtobracket
modelingdomain.Withthereflectionoptionemployed,CMS-
Wave performs a backward-marching scheme to represent the likely range of future global sea levels, considering the
boundaryreflectionaftertheforward-marchingcalculationis possibilityofaccelerationintheglobaltrend.
completed. The implementation of wave diffraction in the Twosynthetichurricanes(tropicalstorms)correspondingto
wave-action balance equation is described by Mase (2001). 50-year and 100-year return periods and a most probable
Additionalmodelfeaturesincludethegridnestingcapability, winter storm (extratropical) that occurred in October 1982
variablerectanglecells,wavetransmission,waveovertopping (Burks-CopesandRusso,2011)weresimulated.Theselection
structures,andwavesetup/setdownonabeachslope.Thewave of the hurricanes was based on 460 synthetic hurricanes
setup/setdown is computed on the basis of the horizontal designedinaFederalEmergencyManagementAgencystudy
momentumequations,neglectingcurrent,surfacewinddrag, fortheVirginiacoast(Blantonetal.2011;Forteetal.2011).
andbottomstresses.Forthiscalculation,changeinthemean Thejointprobabilitymethodwithoptimalsamplingwasused
waterlevelisrelatedtothetransferofwavemomentumtothe todevelopthe460modelhurricanes(Vickeryetal.2010).The
watercolumnduetowavebreaking(DeanandWalton,2009). stormparametersincludecentralatmosphericpressure,radius
CMS-Flow and CMS-Wave can be coupled and operated ofmaximumwind,translationspeed,heading,andtheHolland
through a steering module available in the surface-water
B parameter (Holland 1980). The storm return periods were
modeling system (SMS). The framework of CMS is shown in
determined primarily by examining water-surface elevations
Figure1.Zundel(2006)providesdetailsabouttheSMS.
measuredatlocaltidalgaugesandstormsurgesgeneratedby
The CMS has been widely applied to open coasts, coastal
thesynthetichurricanes.
inlets, bays, estuaries, Great Lakes, and Pacific Islands
The extratropical storm was selected from 30 historical
(Demirbilek et al., 2010; Demirbilek and Rosati, 2011; Li et
storms (northeasters)that affected the Norfolkareabetween
al., 2009). Some recent applications include Grays Harbor,
1975 and 2008. The October 1982 storm is one of the most
Washington; San Francisco Bay and Bight, California; Noyo
severestormsthataffectedtheregion,theselectionofwhichis
Bay,California;GalvestonBay,Texas;MatagordaBay,Texas;
basedonthemaximumwater-surfaceelevationsmeasuredat
ChesapeakeBay;SharkRiverInlet,NewJersey;theBigIsland
theNOAAtidegaugesatSewellsPointandChesapeakeBay
ofHawaii,Hawaii;ClevelandHarborinLakeErie;andRhode
Islandcoastandlagoons(CIRP,2012). BridgeTunnelinlowerChesapeakeBay.Generally,thepeak
Coupling the flow and wave models and including calcula- surgelevelsproducedbyextratropicalstormsarelower,butthe
tions of sediment transport and morphology change, the surgedurationsarelongercomparedwiththosebyhurricanes
present study investigatedfiveRSLRscenarios of0(existing (daysvs.hours)(Burks-CopesandRusso,2011).
condition), 0.5, 1, 1.5, and 2 m that may occur in the next OnthebasisofthefiveRSLRscenariosandthethreeselected
century. From 1927 to 2006, the RSLR at Sewells Point, storms,15simulationswereconducted(Table1),eachfora4-
Virginia (National Oceanic and Atmospheric Administration daydurationincludinga12-hourrampingtime.
JournalofCoastalResearch,Vol.29,No.1,2013
20 Li,Lin,andBurks-Copes
Table1. Simulationsperformed.x’representsa4-daysimulationforthe
correspondingscenario.
Tropical Tropical
RSLR (50-YearReturn) (100-YearReturn) Extratropical
(m) Storm Storm (Winter)Storm
0.0 x x x
0.5 x x x
1.0 x x x
1.5 x x x
2.0 x x x
DATA
A collection of coastline information, topographic and Figure3. Arealdistributionasafunctionofland-surfaceelevation(relative
toMSL)inNavalStationNorfolk
bathymetric data, and land surface features in the Hampton
Roads area was acquired to develop grids for the CMS
simulations. The coastline information in the lower Chesa-
peake Bay was available from the shoreline database of the includingbuildingheights(negativevalues),tomorethan30m
National Geophysical Data Center (2011). The aerial photo- belowMSLinthenavigationchannel(positivevalues).Thered
graphs were obtainedfrom Google EarthPro5.1(2011). The color in the lower left corner indicates the Craney Island
lightdetectionandranging(LIDAR)Network(USACEArmy Dredged Material Management Area. The dikes built sur-
GeospatialCenter,2012)providedthelanddetailtopography rounding the area have a height of about 12 m above MSL.
forNavalStationNorfolkat1-mresolutionandwasincludedin Figure 3 shows the areal variations and areal percentage
the CMS to describe local land features, such as buildings, proportionaltothetotalareaofNavalStationNorfolk(theblue
roads, airport, and other major infrastructure. Topographic linepolygoninFigure2)asafunctionofthevariationsofland
andbathymetricinformationinotherlandandwaterareaswas elevation.Thefigureindicatesthat80%oftheNavalStation
providedwith10-mresolutionfromthecoastaldigitalelevation hasalandelevationoflessthan5mand70%between1and4
modelofVirginiaBeach(Tayloretal.,2008). m.Thelandcoveragedatareflectdetailedlandfeaturesinthe
Figure 2 shows water depth and land surface elevations Naval Station Norfolk. Figure 4 shows different colors
relativetomeansealevel(MSL),fromthetwodatasets.The delineating land coverage relating to grass, forest, concrete
(pavedroads,parkinglots,andbuildings),piers,anddirtroads.
figure displays the deep-draft Hampton Roads navigation
On the basis of these data, sediment grain size, erodibility
channel running across the northern portion of the domain,
characteristics, and bottom friction were specified at each
theNorfolkHarborentrancechannelthatrunsnorthtosouth
computational cell in the CMS (Table 2). Because the Naval
locatedjustwestoftheNavalStation,andafewsmallchannels
StationNorfolkanditssurroundingareaarelargelycoveredby
tothemilitarypiersontheNavalStationwaterfront.Thedata
concrete surfaces and buildings, a large part of land surface
rangefromthehighestelevationofmorethan30maboveMSL,
wastreatedasnonerodible(hardbottom).Amediangrainsize
of 0.2–0.5 mm was specified for the erodible land area
Figure2. Topographicmapofthestudyarea.ThebluelineoutlinesNaval
StationNorfolk.(Colorforthisfigureisavailableintheonlineversionofthis Figure4. Landcoverage(535m)atNavalStationNorfolk.(Colorforthis
paper.) figureisavailableintheonlineversionofthispaper.)
JournalofCoastalResearch,Vol.29,No.1,2013
ModelingofCoastalInundationatNavalStationNorfolk,Virginia,U.S.A. 21
Table2. Specificationsoflanderodibilityandsedimentgrainsizeinthe
CMSbasedonlandcoveragedata.N/A¼notapplicable.
LandCover Erodibility GrainSize(mm)
Grass None N/A
Forest Limited 0.3
Building None N/A
Pavedroad None N/A
Dirtroad Limited 0.5
Parkinglot None N/A
Pier N/A N/A
surroundingNorfolk.AsshowninFigure4,thoseareasinclude
thedirtroad,forest,andgrass.
MODEL SETTING
The regional models, ADvanced CIRCulation (ADCIRC;
Melbyetal.,2005)andSimulatingWAveNearshore(SWAN; Figure6. Windspeedanddirectionofthe100-yearreturnstorm.
http://www.swan.tudelft.nl),providedwaves,wind,andsurge-
level input at the CMS boundary for two synthesized
hurricanes with 50-year and 100-year return periods and a directionsfollowmeteorologicalconventionwhereadirectionof
winterstorm (northeaster). Figure 5showsthe CMSdomain 08 indicates the wind blowing or wave propagating from the
with a small portion of the regional grid displayed in the north. Local wind speed and direction were extracted from
background surrounding the Naval Station Norfolk. The ADCIRC simulations for the same storms. The wind plots
western open boundary of the CMS is located in the mouths indicatethatthetropicalstormpassingoverthestudyareahas
of the James and Elizabeth rivers, the northern and eastern
apeakwindspeedof33.2m/s(74.3mi/h).Incidentstormwaves
openboundaryareinChesapeakeBay,andthesouthernopen
providedbySWANpropagatefromtheAtlanticOceanwitha
boundarymainlycrossesthelandsouthofthecityofNorfolk.
waveperiodof16.7secondsandapeakwaveheightof4.3m.
TheCMSnonuniformrectangulargridhasmorethan500,000
gridcells,whichpermitsfinerresolutionwith10-mspacingin
areasofhighinterestsuchasNavalStationNorfolk.
Figures6and7showwindandwaveconditionsassociated
with the 100-year return storm, respectively, at a location
adjacenttotheeasternopenboundary.Boththewindandwave
Figure 5. Study area. The rectangle delineates the CMS domain and
trianglesindicatetheregionalmodelmesh.Cyclesaretimeseriessitesat Figure7. Waveparametersofthe100-yearreturnstormundertheexisting
SewellsPoint,westofthenavalbase(SP),northofthebase(NB),theeastern conditionandfoursea-level-risescenarios.(Colorforthisfigureisavailable
openboundary(EB),andonland(LS). intheonlineversionofthispaper.)
JournalofCoastalResearch,Vol.29,No.1,2013
22 Li,Lin,andBurks-Copes
Figure 8. Surge, 2-m sea-level rise, and tide at NOAA gauge 8638610
(SewellsPoint,Virginia).
Astronomicaltidaldatarepresenting4daysofaspringtide
atSewellsPoint,Virginia(NOAA,2011)wereincorporatedinto
the storm surge provided by ADCIRC for each of the RSLR
conditions in the CMS. The superposition of tide and storm
Figure 9. Spatially varying Manning’s n under the 2-m sea-level-rise
surge provided the water-surface elevation forcing along the scenario.
CMSopenboundary.Figure8showsthe2-mRSLRscenario,in
which the spring tide increased the maximum water-surface
elevationbymorethan0.5mattheforcingboundary.
with predominant wave direction from the east and perpen-
A long-term increase in RSLR will inundate land and
diculartothebaysideboundaryoftheCMSdomain.
eventually create or destroy wetland areas along coastal
The CMS simulated Hurricane Isabel for the period from
regions. To accurately calculate nearshore hydrodynamics,
September 15 to 19, 2003. The model performance was
the storm-surge models represent these long-term effects of
examined by the comparison of the calculated and measured
SLR by a change in vegetation types with corresponding
adjustmentsinbottomfrictionalroughness(McAlpin,Wams-
ley,andCialone,2011).Consistentwiththeregionalsurgeand
wave models, the CMS used four sets of bottom roughness
(Manning’snvalues)forthefourSLRscenarios.Forexample,
forthe2-mRSLRscenario(Figure9),asmallManning’snof
0.02wasspecifiedforopen-waterareasandincreasedto0.15
forvegetationcoverageonland(Chow,1959).
CMS-FlowandCMS-Waveweredynamicallycoupledduring
the simulation at a 3-hour interval. CMS-Flow calculated
current,waterlevel,andmorphologychangeandtransferred
thisinformationtoCMS-Wave.CMS-Waveusedthisinforma-
tionalongwithincidentwavespectratocalculateandtransfer
waveradiationstressesandwaveparameters(height,period,
and direction) to CMS-Flow to complete one coupling cycle.
This process was repeated for the 4-day duration of each
simulatedstorm.
VALIDATION WITH HURRICANE ISABEL
The CMS capability for nearshore surge calculations was
validated with measurements from Hurricane Isabel, a
devastating hurricane that affected the Norfolk area in
September 2003. Specification of the primary driving forces
forHurricaneIsabelissimilartowhatwasdescribedabovefor
thesynthesizedstormsandwillnotberepeatedhere.Figure10
showstheinputwater-surfaceelevationandwinddata,with
the maximum level at 1.9 m above the MSL and maximum
Figure 10. Surge, tide, and wind of Hurricane Isabel at NOAA gauge
wind speed of approximately 29.0 m/s. Figure 11 shows the 8638610(SewellsPoint,Virginia).
inputwaveconditionswithamaximumwaveheightof3.5m
JournalofCoastalResearch,Vol.29,No.1,2013
ModelingofCoastalInundationatNavalStationNorfolk,Virginia,U.S.A. 23
Figure13. Themaximumwater-surfaceelevationduetoHurricaneIsabel.
(Colorforthisfigureisavailableintheonlineversionofthispaper.)
Figure11. WaveparametersofHurricaneIsabel. processshowsthatthecoastaleffectsonthechangesinsurge
amplitude and phase from deep to shallow waters are well
representedintheCMS.
Figure 13 shows the spatial distribution of the maximum
water-surfaceelevationatSewellsPoint,Virginiaasshownin
water-surfaceelevations.Thesimulationresultsindicatethat
Figure 12. The correlation coefficient between the CMS-
about6%ofthelandareaaroundthemilitaryinstallationswas
calculated water levels and the measured data is 0.990. The
inundated from Hurricane Isabel. The flooded areas are
root mean square error (RMSE) and the relative RMSE
generally flat and have a ground elevation of less than 2 m
(RMSE/datarange)are0.076mand3.6%,respectively.
aboveMSL.Becausewavesbreakinshallowwater,theCMS-
Comparingthesynthesizedwater-surfaceelevationspecified
calculatedsignificantwaveheightsatthefloodedareahavea
at the CMS open-boundary in Figure 10 with the calculated
smallaveragedvalueof0.08m.Additionalfloodedareasdueto
results in Figure 12, it can be seen that the storm surge
waveeffectscanbeestimatedbythepeaksurgelevelof2mand
propagates from the bayside as indicated by the phase
therelationshipbetweenthechangeinlandelevationchange
differencebetweensurgelevelsatthecoastalandtheboundary
and flooded area percentage (Figure 3). To investigate this
locations.Asthesurgewavesapproachthenearshoreshallow
effect, water levels were increased by 0.04 m, half of the
area,thewater-surfaceelevationatSewellsPointhasa0.1-m
averagedsignificantwaveheight,whichresultedinanincrease
amplitude increase and a 1-hour phase lag. The validation in the corresponding area changes of 1.0% of the total area.
Therefore,a relativelylargeresponsetooverlandinundation
shouldbeexpectedifwaveeffectsareconsideredbesidessurge,
tide,andwind.
ThemostseverelandinundationintheHamptonRoadsarea
wascausedbytherainfall-ledflashfloodingandriverflooding
during Hurricane Isabel (http://en.wikipedia.org/wiki). The
post-Isabel flooding damage at Naval Station Norfolk was
describedandthreeinundatedareasbythestormsurgewere
identified by Angela Schedel and Eugene Lambert (personal
communication, June 5, 2012).As shown in Figure 14,those
areasincludeaparkinglot(PKL),theNavalBaseGolfCourse,
and an area adjacent to Mason Creek, all located in the
northern side of the base. No flooding map is available for
HurricaneIsabel,whichpresentsdifficultiesforaquantitative
Figure 12. Water-surfaceelevationcomparisonbetweenthecalculations
comparison between the model results and the survey data.
andmeasurementsofHurricaneIsabelatSewellsPoint,Virginia.
However, the three flooded spots correspond well to the
JournalofCoastalResearch,Vol.29,No.1,2013
24 Li,Lin,andBurks-Copes
Figure14. Thepost-IsabelfloodedlocationsatNavalStationNorfolk.(Colorforthisfigureisavailableintheonlineversionofthispaper.)
calculatedfloodingcoveragebasedonthemaximumsurgelevel surge levels are generally higher. The difference in surge
(Figure13). betweensitesSP,NB,andEBcanbeaslargeas0.4m,which
clearly displays the nearshore water pileup as tidal waves
RESULTS OF SYNTHETIC STORMS propagate from open water to the harbor area. A different
inundationpictureisshownatsiteLS.Normaltidalconditions
TheCMSsimulatedtheexistingcondition(0mRSLR)and
wouldnotfloodtheinstallationareaadjacenttothislocation
four other RSLR scenarios (0.5, 1, 1.5, and 2 m) for Naval
fortheexistingcondition,the0.5-m,and1-mSLRcases,but
Station Norfolk with three selected storms, the 50-year and
wouldforthe1.5-mandthe2-mSLRcases.Thestormsurge
100-year-return tropical storms and an extratropical storm.
wouldraisethepeakwaterlevelto3.643mundertheexisting
Thestorm-inducedinundationwasinvestigatedandevaluated
conditionandto5.430munderthe2.0-mSLRscenario.
bysurge,waves,andwindeffects.
Table3presentsalistofareasinundatedbecauseofthe50-
yearand100-yeartropicalstormsandtheextratropicalstorm,
Storm Surge with different SLR scenarios for Naval Station Norfolk. The
Surge level is analyzed as an important indicator of land results show that the flooded area expands as the RSLR
inundation under the existing condition and four RSLR increasesfrom0to2.0m.Amongthethreesimulatedstorms,
scenariosforthreeselectedstorms.Figures15(a)and(b)show the 100-year storm inundates more than 60% of the area for
the maximum water-surface elevations under the existing differentRSLRscenarios.Allthreestormscauseinundationof
conditionandthe2-mRSLRscenarioforthe100-yearreturn approximately60–80%ofNavalStationNorfolkunderthe2-m
storm, respectively. Because Naval Station Norfolk has land RSLRscenario.
surface elevations generally less than 4 m above MSL, most TheCMSresultsshowedthatHurricaneIsabeldidnotcause
areas could be under the maximum surge level for the severeflooddamageinNavalStationNorfolk.Incomparison,
simulatedstorm.ThegreaterlandelevationseastoftheNaval thepeaksurgelevelofthe100-yearstormisnearlytwicethat
Station,CraneyIslandtothewest,andsometallbuildingsstay ofHurricaneIsabelunderthepresentMSL(2.0mvs.3.6m).
abovethemaximumsurgelevelunderthe2-mRSLRscenario. This significantly higher peak water level could result in
Calculatedwater-surface elevations were examined at four floodingmorethan60%ofNavalStationNorfolk.Comparing
locations:sitesEB,SP,NB,andLS(Figure5),locatedatthe Hurricane Isabel with the three synthesized storms, the 50-
easternboundary,SewellsPoint,northoftheBase,andaland yearreturnstormcausesasimilarlandinundationwithinthe
site,respectively.Figure16showsthecalculatedwater-surface NavalStation.
elevationsatthefoursitesfortheexistingconditionandfour
SLRscenarioswiththe100-yearstorm.SiteLSislocatedon
NavalStationNorfolkandhasalandelevationof2.0mabove Waves
the present MSL. Therefore regular tidal conditions cannot AlongtheCMSgridopenboundaries,largesignificantwave
floodthesiteunderthe0.0,0.5,and1.0mSLRscenarios.The heightspropagateintothemodeldomain,decrease,andbreak
wettinganddryingprocessatthelocationisdisplayedbythe aswavesapproachnearshoretowardtheharborand overtop
discontinuityofthewater-surfaceelevationsinFigure16. thelowlandarea.Figures17(a)and(b)showthemaximum
TidalandsurgesignalsatsitesSPandNBcoincidewithtidal significantwaveheightsundertheexistingconditionandthe2-
forcing implemented at the model open boundaries, but the m RSLR scenario at the peak of the 100-year return storm,
JournalofCoastalResearch,Vol.29,No.1,2013
ModelingofCoastalInundationatNavalStationNorfolk,Virginia,U.S.A. 25
Figure16. Water-surfaceelevationofthe100-yearreturntropicalstorm
undertheexistingcondition(0m)andthefoursea-level-risescenariosat
sitesEB,SP,NB,andLS.(Colorforthisfigureisavailableintheonline
versionofthispaper.)
oppositewind-andtide-inducedcurrentsalongthenavigation
channels during the storm passage, and the strong wave-
current interaction seems to induce the large waves at this
location.
Figure18showsthetimeseriesofsignificantwaveheight,
wave period, and wave direction at sites SP and NB. The
calculatedwaveparametersdisplayedatEBaresimilartothe
wavesspecifiedattheopenboundary(Figure6).Waveshave
dissipated and diffracted as they approach Hampton Roads
along the coast. The coastal effects on wave propagation are
evident from calculated wave results at site SP. Dominant
wavedirectionsarefromthewestundertheexistingcondition,
0.5-m,and1.0-mRSLRscenariosorfromthenorthunderthe
1.5-mand2-mRSLRscenariosatsiteSP.Smallshort-period
Figure15. Themaximumwater-surfaceelevationdueto100-yearreturn wind waves are mostly propagating from the west and long-
tropical storm under (a) the existing condition and (b) the 2-m RSLR period swells reach the site from the north. Figure 18 also
scenario.(Colorforthisfigureisavailableintheonlineversionofthispaper.)
showsthatwavesfromthenortheasthaveadirectimpacton
site NB. The wave heights at the two sites indicate that the
floodedlandareasrelatedtowaveactivitiescouldbesmalland
respectively. Wave heights over the flooded area at Naval negligible.
StationNorfolkareconsistentduringthemaximumsurgeand Estimates of the inundated areas in Table 3 are based on
generallyhaveamplitudeofafewcentimeters.Relativelylarge surge-andtide-inducedwaterlevel.Toaccountforwaveeffects
wave heights (greater than 1.0 m) can be identified in the inthecalculations,one-halfofthesignificantwaveheightsare
figure,asseenclosetothebaysidefrontoftheNavalBasefor added to obtain the maximum water mark associated with
different SLR scenarios. North of the CMS domain the wave storms.Thewave-modifiedwaterlevelwillresultinchangesin
heightcanreach6.0munderthe2-mSLRscenario.Thetime flooded areas at Naval Station Norfolk. The maximum
seriesofforcingconditionsandmodeloutputrevealthatwaves significantwaveheightswithinNavalStationNorfolk(Figure
propagatingfrom the Chesapeake Bay side encounter strong 2)wereaveragedandtheresultsareshowninTable4forthree
JournalofCoastalResearch,Vol.29,No.1,2013