ODU8:Eastoke
ODU8:Eastoke
Overview
ODU8includestheEastokepeninsula,whichhasbeensplitintonorthern andsouthernsections.
Thisunitcoversboththeshelteredharbourenvironmentalongthenorthern shorealongwiththehighlydynamicsouthernopencoastfrontage,bothof whicharefrontedbysignificantenvironmentaldesignations.Thisresultsin thecomplexchallengeoftidallydrivenfloodriskintheharbourcoupledwith highenergywaveovertoppinganderosionriskalongtheopencoast.
Theareaisheavilyurbanisedandalsocontainsseveralholidayparks,aRNLI station,sailingclub,marinaandnaturereserve.Thesouthernfrontageiswell usedbyresidentsandtourists,soaccesstothebeachisimportant,andthe draftHavantBoroughCouncilLocalPlanidentifiesopportunitiesfor regenerationalongsomepartsofthesoutherncoastline.
Environment
TheintertidalHarbourareatothenorthandeastofthisfrontageis environmentallydesignatedasSSSI,Ramsar,SPA,SACand,alongwiththe northernlandwardfringe,spitandSandyPointLocalNatureReserve,falls withintheChichesterHarbourNationalLandscape.ThenatureReserveis alsoenvironmentallydesignatedasSSSI,RamsarandSPA,whiletheopen coastsubtidalareaisadesignatedSAC.
CoastalProcesses
HaylingIslandisunusualcomparedtootherlocationsinthatitsbeachesare susceptibletobi-modalwaveconditions,wherelongperiodswellwaves refractaroundtheIsleofWight,coincidingwithlocalstormconditions.This resultsinveryenergeticwaveconditionsthatcanbeextremelydamagingto thecoastline.
Defences
Thereareawidevarietyofdefenceshere,includingseawalls,sheetpiling, rockrevetments(aspartoftheEastokeSchemecompletedin2005)and groynes.Themajorityofdefencesalongthenorthofthefrontagehave residuallivesbetween10and20yearsandareprivatelyownedand maintained,withtheexceptionofdefencesimmediatelywestofSparkes MarinawhicharemaintainedbytheEnvironmentAgency.Asyoumore roundtothesouthofthefrontage,rockrevetementsareingoodcondition andareownedandmaintainedbyHavantBoroughCouncil.Thebeachitself isavitalcomponentofthecoastaldefenceandiscurrentlymaintainedby HavantBoroughCouncilthroughbeachnourishmentandbeachrecycling whichtakesplaceatregularintervals.
ShorelineManagementPlanPolicy
HoldtheLineforthenext100years.
Risk
Therisksherearepredominantlyfromwaveovertoppingandcoastalerosioninthesouthandtidalfloodingfromthe north.Thesouthernfrontagehasalonghistoryofhighenergywaveaction,whichresultsinsignificantbeach drawdown,cutbackandlossofmaterial.Thisisduetobi-modalwaveconditions,whenlongperiodswellwavesrefract aroundtheIsleofWight,coincidingwithlocalstormconditions.Theresultishighlyenergeticwaveconditionsthatcan beverydamagingtothecoastline.
InthefuturethereisariskofjoinedupfloodingacrosstheentireEastokepeninsularandassuchtheunithastobe treatedasonecompletefloodcell.Thereareupto1,253propertiesatriskoferosionand1,472propertiesatriskof floodingoverthenext100yearswithoutdefences.
Themapsbelowshowthemodelledextentanddepthsofanextremetidalfloodevent(1in200year,0.5%annual probability),withoutanydefences,todayandin100years,allowingforsealevelrise.
Erosionrisk
Numberofpropertiesatrisk,withnodefences
Tidalfloodrisk
Numberofpropertiesatrisk,withnodefences
Donothing damages
£286,875,000 PresentValue
Thestrategicintentintheveryshorttermistorenewtheexisting BeachManagementPlanandimplementthisoverthenext5years (2024-2029).However,itisrecognisedthatbeyondthisamore strategicsuiteofmeasureswillberequiredtoprotecttheentire peninsula.Thiswillinvolvethedevelopmentofasinglepeninsular wideschemeunderonebusinesscasewithaprogrammeofworksto constructnewdefencessuchasfloodwallsalongthenorthernfrontage andthebuildingofanewrockrevetmentalongpartsofthesouthern frontage;coupledwithnewrockgroynes.Ontopofthisongoingbeach managementwillberequiredtomaintainahealthyandrobustbeach toreducetheimpactsofhighenergywaves.
NextSteps
FurtherstudiesintoBi-modalwavesarealreadyunderwayto understandtherisktothiscoastalunitwhichwillinformfuture managementofthebeach.AFloodandCoastalErosionRisk ManagementSchemeforEastokehasbeenproposedintheStrategy’s shorttermactionplan.Subjecttosecuringfunding,thiswillstartwith afeasibilitystudytolookatandappraiseappropriatecoastal managementoptionsforthepeninsular.