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1 INTRODUCTION
AccordingtoNichollsetal.[1],portcitiesareavital
component of the global economy and are
increasingly becoming important concentrations of
populationandassetvalue.Thirteenoutofthetwenty
most populated cities in the world in 2005 are port
cities.
Sealevelrise(SLR)and
theincreasingoccurrence
of stronger storm surge events in metropolitan
regions of ports cities with more than one million
inhabitantsin2005wereanalyzedbyNichollsetal.[1]
and ranked according to exposed population and
assetsin2005and2070,includingSantos(Brazil).
SantosPortis situatedinSantos
Estuary,State of
SãoPaulo(Figure1),isthelargestmulti‐purposeport
inSouthAmerica withoverthan13kmofquays.Per
year, a throughput of 120 million tons of cargo is
made[3](Figure1).
The estimation about the magnitude of SLR in
recommendations,guidelinesorrequirementsissued
by different countries and agencies [3] provide
examples of different approaches used around the
world in comparison with the local trends obtained
forSantosPort.
Estimation and Impacts of Sea Level Rise in Santos Port
and Adjacent Areas (Brazil)
P.Alfredini&E.Arasaki
SaoPauloUniversity,SãoPaulo,Brasil
ABSTRACT:SantosPortislocatedinBraziliancoast,inan estuarinearea insideSantos BaynamedBaixada
Santista.Thecurrentsbehaviorisforcedbytides.Theresultingtidallevel variability(hightide,meansealevel
andlowtide)recordedfrom SantosDockCompanytide gauge
(1940to 2014)shows aconsistent increasing
trend.Theestimationaboutthemagnitudeofmeansealevelrise(MSLR)inrecommendations,guidelinesor
requirementsissuedbydifferentcountriesandagenciesfrom1990provideexamplesofdifferentapproaches
usedaroundtheworldincomparisonwiththelocaltrendsobtainedforSantos
Port.ItisconcludedthatMSLR
willhaveaconsiderableimpactupontheportandadjacentareas,withapproximately1.0mriseestimatedfrom
1990to2100.BaixadaSantistaisalowlandsituatedafewmetersupperfromthesea levelandsomeareasare
possibletobesubmergedin
theendofthiscentury.Notonlythewetlandsofmangroveswillbeaffected,but
alsotheinfrastructures,residentialzonesandtheportwillfaceproblems.ThemajorSLRimpactsuponport
operationwillbethereductionof freeboard of the quays, flooding of storage yards (and other low storage
areas)andoftheinternaltransporttracksorrails.Alsotheincreasingsedimentationinthenauticalareasof
accesschannels,turningbasinsandberths,willinducemoremaintenancedredging.
http://www.transnav.eu
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 12
Number 4
December 2018
DOI:10.12716/1001.12.04.13
740
2 MATERIAL
2.1 Tidesandmeansealevel(MSL)variabilityinSantos
Port
Longtermsealevelobservationsareusefulformany
researches as: tidal analyses, tidal modeling, studies
oftheoceandynamicsandevaluationofgreenhouse
impacts.Besidethese,worksontheestimationofthe
MSL trends and periodicities
were developed in the
lastyearsinordertoestimatetheratesofchangesof
thesealevel[4‐6].Theseworks,consideringdifferent
longseriesofsealevel,studiedthelong‐termtrends
ofeachlocation.
Figure1. Satellite image of Santos Bay and the estuarine
areas of Santos, São Vicente and Bertioga (Southeastern
Brazil).Locationofthestudyarea,showingSantosPortarea
andPontadaPraianeighborhood,exampleofanurbanarea
whichwillbeinundatedwhensealevelisgoingtorisewith
one
meter from 1990 to 2100. It is also possible to see the
locationofthetidalgaugeofSantosPort.Adaptedfromthe
SourceGoogleEarth/Maps(2015).
2.2 SLRimpactsonportoperationandthesurrounding
neighborhood
These problems, discussed in [2], are basically
consequences of the reduction of quays freeboard,
flooding due to insufficient effectiveness of the
present drainage system and the increasing
sedimentationinthenauticalareas.Makeavailable
informationontheimpactsofclimatechange
onthe
maritime port environment has become an
international issue for ports to address global
warmingimpacts[7].
Thereductionofquaysfreeboardisevidentasthe
quayplatformheightisdeterminedbythelevelofthe
terminalareabehind theberthapronandthehighest
observedwaterleveland
thetidallevel.Accordingto
Thoresen [8], the following zones of concrete
deterioration will migrate upward with SLR: the
permanently submerged zone, below Lowest
Astronomical Tide (LAT, Zone 1) will increase in
height; the tidal zone, between LAT and Highest
AstronomicalTide(HAT),willmigrateupward(Zone
2); the splash zone
(Zone 3), above HAT, which is
periodicallyexposedtowaterfromwaves,willaffect
thequaysaprons;theatmosphere(Zone4)willaffect
higherstructures of the quay apron(see Figure 2 as
anexample).
SLR also may contribute for increasing
sedimentationinthenauticalareas.Consideringthat
mangrove forest
in Baixada Santista retains in its
roots much sediments, part of the solution for this
second problem would lie in measures to preserve
these mangrove forests. In a study by Tusinski and
Verhagen[9],itwassuggestedthatmangroveforests
can serve as an effective coastal defense, including
trappingsedimentwithin
theirroots.
3 METHODS
3.1 AboutSLR
The Projected SLR resulting from simulations of
differentclimatescenariosfromtheworkundertaken
bytheIPCC[5]increasesfrom1986–2005to2081–
2100intherangefrom0.26to0.82m.However,itis
evidentthataMSLRin
therangeof0.40to0.63m,i.e.
intheorderof0.50min2081‐2100isexpectedasan
averageofallthemodelingresultsreportedinIPCC
[5].
Figure2.Verticalprofilesofsometypicalquaysandpiersin
the Santos Altimetry Datum. Original project drawings
fromthePortAuthority.
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A likely scenario to use as practical
recommendation seems to be that the SLR in year
2100willbeintherangeof0.5mto1.0m,however
withariskofbeingabout50%higherandthatthesea
level will continue rising also after year 2100,
according
toTable1[3].
There are many approaches for determining an
appropriate MSLR scenario, but it is impossible to
predictexactlyhowthefuturesealevelwilldevelop.
Consequently, various authorities have developed
differentestimations[3]asfollows.
As example of local practices, the DEFRA –
DepartmentforEnvironment,Food
&RuralAffairsof
the UK Government [4] in anticipation of increased
futureSLR,recommendthatnewengineeringprojects
witha100‐yeardesignlifearerequiredtoincludeup
to1mofSLRfrom1990,recognizingthattherateof
riseisexpectedtobelargerattheend
ofthiscentury
thanatthebeginningofthecentury(Table2).Other
local practices mentioned by PIANC [3] are the
projections of the Delta Commission in The
Netherlands(projectingupto1.4mMSLRfrom1990
to 2100 and for USA: California, Oregon and
WashingtonStates(Table3)from
2000.
Considering the period of 1990 to 2014 as an
adjustmentperiodforthecalibrationoftheMSLRrate
obtainedfromthetidegaugeofSantosPort,thiswas
compared with the rates of UK [4] (moderate rate),
StatesofCalifornia,WashingtonandOregon[3],The
Netherlands Delta Project (equivalent to
Rahmstorf
[6], higher rate), PIANC [3] higher and lower rate,
IPCC [5] higher and lower rate and Rahmstorf [6]
lowerrate.Fromtheserates,wasadoptedthebestfit
toforecastMSLRrateforSantosPorttill2100.
3.2 ThequaysinSantosPort
The quays in Santos Port are
named according the
depthoftheberth(CDSDatum).Figure2showssome
typical vertical profiles of the quays. The design
freeboard observed was 1.58 m, defined in the
projectsmore than 70 yearsago (original drawings),
consideringaHigherHighWater(HHW).Nowadays,
this freeboard is not the same, due
to the SLR
occurred.
Table1. Example of scenario for sea level rise (SLR) as
function of type of infrastructure impacted by the design
eventaccordingtoPIANC[3].
_______________________________________________
Typeof Severity TypicalSLR(m)inyear
infrastructure offailure 2030 2050 2100 Laterthan
2100
_______________________________________________
Farmlandand low 0.1‐ 0.2‐ 0.5‐ Upto1.2
recreational0.2 0.4 1.0
facilities
Habitationandmedium 0.15‐ 0.3‐ 1.0‐ Upto1.5
infrastructure0.3 0.6 1.2
Majorhabitation,high 0.2‐ 0.4‐ 1.1‐ Upto2.0or
infrastructure0.4 0.8 1.5 higher
andpublic
utilities
_______________________________________________
Table2. UK recommended net SLR rates and cumulative
amounts,relativeto1990[4].
_______________________________________________
Time Lowrate Moderaterate Highrate
period (mm/yr)/ (mm/yr)/ (mm/yr)/
cumulativeSLR cumulativeSLR cumulativeSLR
since1990(m)atsince1990(m)atsince1990(m)at
endofperiod endofperiod endofperiod
_______________________________________________
1990‐ 2.5/0.093.5/0.124.0/0.14
2025
2025‐ 7.0/0.308.0/0.368.5/0.40
2055
2055‐ 10.0/0.6011.5/0.7112/0.75
2085
2085‐ 13.0/0.9914.5/1.1415/1.21
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_______________________________________________
Table3. SLR projections relative to year 2000 for Seattle,
Newport,SanFranciscoandLosAngeles[3].
_______________________________________________
Cities203020502100
Projection Projection Projection
(cm)(cm)(cm)
_______________________________________________
Seattle 6.6±5.616.6±10.5 61.8±29.3
Newport 6.8±5.617.2±10.3 63.3±28.3
SanFrancisco14.4±5.0 28.0±9.2 91.9±25.5
LosAngeles 14.7±5.0 28.4±9.0 93.1±24.9
_______________________________________________
4 RESULTS
4.1 AssessmentoftheMSLR
The tide gauge, which measured water level
fluctuations in Santos Port, provided exactly four
lunarnodalperiods(1940to2014)of18.61yearseach
one (Figure 3).This is an important astronomical
criterion,becausetake inaccount complete cycles of
repeatabilityofthe
MooninfluenceontheMSLtrend,
which estimation make possible to evaluate with
reliability if the tidal level shows a MSLR after
completed each cycle. In the graph of Figure 4 is
presented the mobile average of 19 years
(approximatelythelunarnodalperiod),showingthe
consistentincreasing ofthe
MSL.From1940to2014,
thelineargradientoftheMSLRwasof0.33cm/year
withacoefficientofdetermination.
AsitispossibletoseeinFigure5,thebestfitofthe
calibrationforthelinearMSLRtrendof0.33cm/year
was obtained with UK MSLR moderate rate (0.35
cm/year from 1990 to 2014). Hence, the forecasting
linear trends for Santos Port were plotted following
Table2moderateratefrom2014to2100.
The resulting MSLR from 1940 to 2100 shows a
consistent increasing trend, indeed, compare the
followingforecastsfor2100withreferenceto1940:
174.8cm:
IPCC[5]higherrate.
156.5cm:TheNetherlands (Rahmstorf,[6],higher
rate).
134.8cm:PIANC[3]lowerrate.
112.8cm:CaliforniaState.
108.9 cm: linear trend of the record of the tide
gauge of Santos Port from 1940 to 2014 and
adjustedfrom2014withUK
[4]moderaterate.
108.3cm:IPCC[5]higherrate.
82.8cm:OregonandWashingtonStates.
54.5cm:Rahmstorf[6]lowerrate.
47.0cm:IPCC[5]lowerrate.
108.9 cm: Average value of the mentioned nine
MSLRestimationsfrom1940to2100.Itisexactly
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equalforSantosPortMSLRrateproposedinthis
paper.
4.2 Thereductionofthefreeboardofquaysandpiers
The original design freeboard of the majority of
SantosPortberthsis1.58m,referredto1940’s.Hence,
with a 1.1 MSLR from 1940 to 2100, results in a
freeboard
reduction to 0.48 m, value not proper for
thequayoperation(seeFigure5).
5 DISCUSSION
5.1 TidaltrendforMSLRin2100forSantosPort
MSLR trend of Santos Port tide gauge from 1990 to
2014 was compared with the recommended rates of
UK [6] (moderate rate), States of
California,
Washington and Oregon [3], The Netherlands Delta
Project(equivalentto[6]higherrate),[3]higherand
lower rate, [5] higher and lower rate and [6] lower
rate. The best adjustment occurred with UK
recommended rate [4] (moderate rate), but also
CaliforniaStateand[5]higherratearequitesimilar.
The
average MSLR from 1940 to 2100 from all the
mentioned methods is identical of Santos Port
projectionto2100usingUK[4](moderaterate).This
isanimportantresult,showingtheconsistenceofthe
suggestedratetobeadoptedforMSLRrateforSantos
Portforthenextdecadesof
thiscentury.
5.2 ThecaseofSantosPort
The impact on the reinforced concrete maintenance,
due to the deterioration of concrete in marine
environmentscanoccurindifferentzones.Theusual
vertical zonal division of structures in marine
environment[8]demonstratethattheSLRwillaffect
allthefourzonesdescribed.
Eachzonehas different
requirementsonthecompositionoftheconcrete,the
placingandcovering ofthereinforcement,thedesign
load coefficients, the materials coefficients, etc. [8].
Considering the six quay and pier types, of Santos
Port,itispossibletoclassifythefollowingschangings
aboutthemaintenanceprocedures for
thereinforced
concrete:
In this context, it is necessary to be aware that a
serious impact in the durability of the reinforced
concrete structures will occur, and preventive or
corrective maintenances have to prevent the
reinforcedconcretedeteriorationwithproperrepairs.
The average height of quays in the Santos Port
were
1.58 m above the sea level in 1940, but with a
MSLRof1.1mbytheyearof2100,thisheightwillbe
reducedto0.48m,quiteinsufficient.
Otherimportant consequencesofSLR in theport
area are flooding of storage yards (and other low
storageareas)and
ofthe internaltransport tracksor
rails. Hence, the present drainage system will be
insufficientintherainyseasons.
5.3 Impactonthemangrovewetlands
According to the SLR assessment, in 2100 there will
beaSLRof1.0mfromthereferenceyearof1990and
probablytherewillbe
alossof26.3%oftheriparian
zone of existing mangroves, corresponding to 27.4
km
2
. Without this retention, a larger amount of
sedimentwillbecarriedtotheinnernauticalareasof
Santos Port, silting and increasing the dredging
volumes of maintenance. Furukawa, Wolanski and
Mueller[10]describedthatupto80%ofthesediment
deliveredbythetides may be retained inmangrove
areas,
eventhoughthemechanismofretentionofthis
sedimentisunclear.
Figure3. Graphof Santos Port annual tidal level variability from 1940 to2014. Linear trends of MSL (Mean SeaLevel),
HHW(HigherHighWater)andLLW(LowerLowWater).
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Figure 4. Graph of tide mobile average of 19years for MSL, HHW and LLW in Santos Port. Itis possible to observe a
consistentSLRofthelevelsfrom1990.
Figure5.GraphofSantosPortMSL lineartrendfrom1940to2014,withtheperiodofadjustment(1990to2014)forthe
selectionof the best fit among some of the most known proposed methodsworldwide.Projectionfrom1990to2100for
SantosPortMSLtrendadjustedandcomparisonswith
theworldwiderecommendations.
6 CONCLUSIONS
TheassessmentofSLRinSantosPortshowsareliable
consistence in comparison with several worldwide
recommendations, giving confidence to its use for
impactsestimativeduetothismaritimeconsequence
of climate changings. The estimative of MSLR from
1940to2100 is1.1m,followingfrom 1940to2014
a
rateof0.33cm/year,whichwillincrease.
The quays freeboard reduction is a direct
consequence of SLR, affecting the maintenance
procedures, due to the changing of the zones of
reinforced concrete deterioration. The present
drainage system will be insufficient in the rainy
seasons,producingmoreconditionsofflooding.
The
increasinginthesalinityintrusionupwardthe
estuaryduetohighertidallevelswillseriouslyaffect
the riparian mangroves and will reduce this fine
sedimenttrap.
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