CoastalScience&Engineering• CSEfoundedin1984• MostSCnourishmentandgroin
experienceofanyprivategroup• Completedover40nourishmentprojects
sincethe1980s.• MajorprojectsatMyrtleBeach,Seabrook,
Hunting,Edisto,Kiawah,Folly,BogueBanks(NC),NagsHead(NC).
• Servicesincludecoastalerosionassessments,projectdesignandmanagement,coastalstructures,permitting,datacollection,coastalprocessmodeling,CADD.
• WasinvolvedininitialstudiesofKiawahtodevelopconstructionsetbacklines.
• Engineeredandmonitored2006and2015eastendprojects.
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KiawahIsland• ~10milesofbeachalongamostlyeast-westconfiguration
• Stono Inlettoeast,CaptainSams Inlettowest
• Mostoftheislandhasaccretedoverpastseveraldecades(1-10ft/yr)
• Developedafterstudiesofthebeachprocessescompleted
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ShoalBypassingatStono Inlet
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Large-scaleshoalbypassing
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1860sBeach
1960sBeach
1998
20032005
FlushingChannel
2006RestorationProject
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• Moved~550,000cy• Inletrealignmentplusbeachrestoration
• Usedland-basedequipment
Post-ProjectMonitoring
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A – DuneB – WashoverC – S. IntertidalD – S. SubtidalE – Vegetated MarshF* - E. IntertidalG* - E. Subtidal
HabitatAreas
2015Project
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2015ChannelRealignmentProject• Moved100,000cy• Limitedbeachrestoration
• Focusonhabitatconservation
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KiawahIslandBeachMonitoringStations
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KeyEvents2015-2016• ChannelRealignmentProjects– Spring2015• HurricaneJoaquin– October2015• 2015Survey– November• HurricaneMatthew– October2016• 2016Survey– Jan2017(delayedforenvironmentalmonitoring)
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HurricaneMatthewImpacts• Matthewimpactedthebeacharound8October2016asaweakCategory2storm.WindsinCharleston~75mph.
• Approachedonfallingtide• Resultedinsignificantdunerecession,damagedwalkovers,minorflooding
• Stormprofilevsnaturalprofile
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DuneErosionDuringMatthew
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Post-StormConditions
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OceanCourse EugeniaAve
Post-StormConditions
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2015-2017VolumeChangesReach Name 2015-2017Unit
VolumeChange2015-2017TotalVolumeChange
2007-2017Average
1 KiawahSpit* -10.7 -94,586 -9.2/-0.1
2 WestBeach -11.5 -135,187 0.7
3 TurtlePoint -14.3 -195,106 2.7
4 OceanCourse -3.8 -34,515 6.8
5 Lagoon -23.2 -185,717 1.8
6 StonoInlet -33.6 -201,328 -7.4
1-6 All -14.8 -846,439 -0.1
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~750,000cywerelostduetorelocationofCaptainSams Inletin2015.Accountingforthisresultsinthenetchangeof0.1cy/ftperyear.
2015-2017VolumeChanges• Overalltheislandlost~850,000cyofsand• ~Halflostfromeastendandhalffromdowncoastareas
• Residentialzonelost~330,000,whichis2-3yearsworthoftypicalaccretion
• ErosionmostseverebetweenMarinersWatchandTurtlePoint#14.
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BeachRecovery• Calmweatherpromotesbeachrecovery.• Sandmovesfromunderwaterbarstothedrysandbermanddune.
• Sandlostfromsystemneedstobereplacedbynewsandfromupcoast.
• EvidenceofrecoveryinJan2017andevenmoreinFeb2017.
• Recoveringduneshavewind-blownaccumulationsatthebaseandspreadingsparsevegetation,drysandseawardofdunetoe.
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PostStormandJanuary2017Conditions
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OceanCourse
PostStormandJanuary2017Conditions
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TurtlePoint
PostStormandJanuary2017Conditions
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EugeniaAve
PostStormandJanuary2017Conditions
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KiawahSpit
EastEndChanges
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~1,400ftmigration2015-2017
EastEnd– February2017
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ConstructedInlet
NewInlet
Flushingchannel
EastEndChanges
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CaptainSams Inlet• Inletrelocated~3,000fteastin2015
• 140,000cyremovedfromnewinletbasin
• Migrated~325ftfromJuly2015toJan2017.
• Historicalrate200-300ft/yr
• Endofspitisrebuildingnormalshape
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CaptainSams Inlet
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SummaryandRecommendations• Overalltheislandlost~850,000cyofsandfromNov2015toJan2017,mostlyduetoHurricaneMatthew.Erosionwaswidespread.
• Duneerosionbetween15and40ftalongresidentialarea,higheralongKiawahSpit
• RecoveryoftheduneisongoingandshouldbemonitoredbytheTown
• Noemergencyactionispresentlyrecommended• Shouldsandfencebeinstalled,itshouldbeplacedasclosetotheprimaryduneaspossible
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SummaryandRecommendations• Theeastendprojectareacontinuestoevolve• Matthewopenedanewchannelnearthe2006channellocation
• Thepondedareanearthedrivingrangeismostlycut-offfromtidalexchange,reducingerosionthreat
• Permitallowsforanotherprojecttobecompleted,ifnecessary,in2018
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