Ocean and Coastal Engineering

8/11/2019 Ocean and Coastal Engineering

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UNIVERSITITEKNOLOGI

VBB4413.OCEANAND COASTALENGINEERING

03 JANUARY2014 (FR|DAY)

9.00 AM- 12.00 NOON(3 hours)

INSTRUCTIONSTO CANDIDATES

1.

2.

3,

4.

Answer ALLquestions in the AnswerBooklet.Begin EACHanswer on a new pagelndicateclearlyanswers that are cancelled, ifany.where applicab[e,show clearly steps taken in arrivingat the solutions andindicateALLassumptions, ifany.

Do not openthis Question Bookletuntilinstructed.

Note : There are SIXTEEN(16) pages in this Question Bookletincludingthe cover page and Appendices.

Universiti TeknologiPETRONAS

PETRONAS

FINALEXAMINATIONSEPTEMBER2013 SEMESTER


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a. Elaborate howmangrove forest can reduce wave impactto thecoastal area and explainwhya sufficientmangrove widthis important

to ensure a sustainable protectivebufferzone.[5 marks]

b. TABLEQ1 shows wave statistics near ABClsland. The statisticsgiven is analyzed fromhalf-hourlydata based on 20-minwaverecord. For several offshoreoperations, the significantwave heights(r1r)should not exceed 2 m. Howmany hours of down-timein a year

are to be expected at this location?[6 marks]

TABLEQ1H" lml Observation H. [m] Observation

0.0 - 0.50.5 - 1.01.0 - 1.51.5-2.02.0 - 2.5

3812593231171784812

2.5 - 3.03.0 - 3.53.5 - 4.0

4.0 - 4.5> 4.5

304108

53

137

Total observations = 15942

Explainthe negative impactthat can be potentiailycaused bydredgingwork(sand mining)in the nearshore zone.

[4 marks]


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d. consider a wave trainof 6 s period and 2 m height approaching abreakwater head at an angle (g) of 60"as shown in FIGUREel. Thewater depth in the lee side of the breakwater is 10 m. Determine thewave height in the lee side of the breakwaterat pointA if it islocatedat an angle (p) of 30"and 100 m (r) fromthe breakwaterhead.

[5 marks]

FIGUREQI


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a. TABLEQ2 shows a time series wave data arranged in descendingorder. Determine Hr*,Tr*,Hr, Hr^ and Hr.

[5 marks]TABLEQ2

Wave height, H (m) Wave period, Z (s)4.553.893.753.65

3.443.443.263.182.862.792.45

2.322.151.951.951.92

1.75

1.581.461.351.22

8.9o

8.09.3

8.58.410.5

10.8

8.47.58.4

7.26.57.98.69.58.1

7.67.47.2

8.1

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b. A deepwater oscillatorywave wth a height of 2 m and a period of g smoves shoreward withits crest parallelto the depth contours.

Do you expect the wave refraction:at a water depth of2 n? Why?

[1 mark]

waveina2m

[4 marks]

il Calculate the celeritya,nd height of thewater depth.

c, Howdoes sign'ifieanttidalfluctuationor tdal range influencethewater qualityin a semi enclosed lagoon?

[5 marks]

d. lllustrate the design process to derive the appropriateplatformlevelof a jettydeck. Make necessary assumptions and providea relevantsketch.

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a. A coastal town in the Mediterraneans wellknownwithalmostnegligbletidalrange whereas port Klang,selangor is generally

experiencinga maximumtidalrange of about 6 m. Howwillyouchoose between the two locationsfor a proposed marina project?Give the basis of yourcomparisona,nd concerns.

[5 marks]

b. Propose how the informationon tidal fluctuationor tidalrange can becrucallyimportantto navigators heading for shallowports. provide asketch to illustrate.

[5 marks]

A 75 m long fishermen jettywitha 20 mjettyhead was constructedalong Terengganu coastline facing the south china sea. A singre150 m longoffshore breakwaterwas also buirtabout 17s m seawardsof the jetty head to shelter the jettyfromwaves. Aftertwomonsoons,a substantial pile of sand accumulated fromthe shoreline extendingtowards the lee side of the breakwater whichcovers mostportionofthe jetty, includingthe jettyhead. Elaborate the coastal processesinvolvedand mechanism(s)responsible for this shoreline response.Use sketch to illustrate.

[5 marks]

d. A beach nourishmentwas earlier designed using a given significantbreaking wave heightof 2 m. The new beach was supposed to lastfor two years before subsequent maintenance cycle.However,it waseventuallyfound out that the significantbreaking wave height to benow I m. Howlong the nourishedbeach can potentiallysurvive?

[5 marks]

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FIGUREQ4 shows three locations (4, B and c) arong a coasfline innortheast on Peninsular Malaysia together witha general nearshore

wave rose for the area. Qualitativelycompare the potentialrelativenet longshore transport between the three locations.

[5 marks]

FIGUREQ4

b. A favouritesandy tourist beach is currentlyeroding. A contractor isemployed to carry out the beach nourishment.Three potential sandsource areas were identifiedwitheach havingmedian sedimentgrainsize of 0.1 mm, 0.6 mm and 1 .2 mm, respectively.The median grainsize (d5 of the native beach material is 0.s mm. Evaruate thefeasibilityof each poterrtialsource and recommend the mostacceptable option.Assume all sand source areas are having thesame distance fromthe projectsite and similarconstructioncost.

3Z

r F)|l^huE -ilI tt-@ [.tI Gr -tEkti

[5 marks]


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c. A newlydeveloped seafront development is protected by revetment.However,duringsevere storms, the revetment was observed toexperience significantovertopping.This has caused serious impactto the permanent property immediatelybehind the revetment.Propose THREE(3) possible measures that can be implementedtoreduce this inconvenience.providea sketch to illustrate.

[6 marks]

d. A series of groynesystem is consdered to be one of the promisingmitigationmeasures against coastar erosion. suggest

rwo(2)

keyelements that willjustiffand ensure a successful implementationof aparticufarscheme.

[4 marks]

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5.

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The head section of a pair of breakwaters fora minorport is plannedat an average water depth of 10 m. Record shows that the maximum

deep water wave heightwithinthat region is about 4 m. The head ofa rubble-moundbreakwater is to be constructed witha face slope of1v:2H.The breakwater is to be designed forminorovertopping.

i. Propose the maximumwave height that can be conservativelyused for the preliminarydesign of the breakwater head andjustifyyour rationale.Assume straght and parallelcontours.

[2 marks]

ii. lfretrapod are to be used as the armour unit,determine theminimummedian weightrequired. Use relativedensity,S = 2.4.

[2, marks]

iii.The capacity of the availableplant or machineryin handringthe armour unitat site is limitedto not more than 10 tonnes.Determine whetherit is practicallyfeasible to handre therequired size of rough angular quarrystones ifthey are usedas the armour unit(relativedensity, S = 2.65).

[2 marks]

iv. lllustratewitha sketch a typical cross-sectionof a quarrystonerubble-moundbreakwater showingthe pertinentcomponentsof the structure.

[2 marks]


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b. Elaborate TWO (2)scenarios where the use of floatingbreakwaterswillnot be effectiveas compared to conventional rubble-moundbreakwater.

[4 marks]

A head section of a pair of offshoredetached breakwaters s to beconstructed at a water depth of 12 m. lfquarry stones are to be usedas the armour layer, it is estimated that this willrequire armour un,itwithmedian size of 35 to s0 tonnes. The nearest granite quarry,

approximately300 km away, is able to produce a maximumrocksizewithaverage diameterof 1.2 m. Appraisethe feasibilityof suchbreakwater constructionand highlightrwo (2) potential concerns insuch situation.

[4 marks]

compare the main design functionsbetween offshore breakwatersand groyneseries. Providerelevant sketches to illustrate.

[4 marks]

-ENDOF PAPER-

d.

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APPENDIXI

Surnntary of Linear{Airy)Wave Theory(SmallArnplitudeYlfaveTheorr)-Wave Gharacterstics/Relatonship

Note:q=aoos(lx-or) o=4 *= c-_2n2TT)

RelativeDepfr ShallorWatert.LL20

k ' 2 LL l 2----


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a{ai. {

APPENDIXIIb

dlL sf d. f${H[tcost aJfi rrd/ .5il0tf t, .rrd, tit.

"'o , . UrVr.'.rrt l"ror{t,}2{ }$[.?26 t,ll l*ftl.lll l.l

f .fO '\09ql.S?t t.tll.86s t',I'lott,or .ttal .t?? lrtt.lr9l .1l? t'.6 .tyl,i08 l.l$.f0r1 LUoft;ot , 6r l.oot l,t0o,5o90 .tr2lr;0nf rsi]tti,att 1.10t.60alt .tt l"ll t.oi ,S$ol t'.a i,

1.0l r''1 r{l.Ol trdI l.tTl. rrsSf l,qI',?8,oo?rr t:ffii"r'fff:ii,isr i'i*t' ijr',l&t t;r'o1.T}

.?J1 .6lttLl?s, }ffi,obg.t

''S961'rE?h).s.k

o$.6?91.sflJ.*Tf5.81f

,.{95'.01?

.4:

,676T .,1,?. .6t,61 f '

"Slr .,6tsc.91. ,lf5

.'.9, .'.Yr'gj "L'99,

?I'OLL.eJ3

.rrrL "*S,?.tl .oto' .?l t.r?l

"{6f.&d.Qtt r??S,,101 .?06'S?1? .?9f?r,?tt . f.l..?09 . . p6 ,*.Jqs,'{ \ ,'

'1 2,158.6526 .o*."r2$3?1l)

.65, z.9N,6(5 2;i?2.Lb{6T?,p?g$ l.l/J

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APPENDIXIIIDiffractoncoefficients,K, s a functionof ineident wave angle, o, and

p-osition,r/Land B {fromWiegel, 1962)

a =15.tgt.i rn t t

0J9 t.001.00 1.00t.00 t.00t-0c . t-oot.00 t.00

t.ot 1,0 t-0:r.or 0,99 o.9i.0,97 l.ot, 0-99r-0: 0.99 , 0r9o.ee t,of 1.00

{:I2sl0

0.490.t8ofl. o-tJ. {H5

o.7g , o-tlo-il o.eJo.tE 0.t6s.J t90.J[ l.to.

o.90 0.9?,95 't,O1,05 t-ojt.rx rrl-05 0.t8

r.0l o-v)t.ot t.ott.(xt 1.00,.00 r.f'r.00 t,00

lmt,00t.0ot.00LOo

I =)'Ut:tTO

g.,to. ,o.+ qJ? 0.1{r.r}?_J o.e i: o.ss i.oio.I .6) o.gq s-7_ g{? o.9r t. Htt_. t.oJ . t.ot t}94 t 9t l.{,oqro or . g.l 9.1 q.?. t.+ is o:t- orE i;oi' iil o:ti i.rt3r 0. : g,l5 't.09 t.or t.0{ t.0 or o.r i.ooo.an flr ' o-tt ht: t-0 c-?t . o_ee i;i' i m frt

6.trt 0.9J lJott 9? r.001.00 0J8 t0.an fL { :ll t.o& ?? ..99 t.ar' 1.00 l.0o

u2 0..e o,Jr oJJi 0.18 o.r0 *7r o,9 o.t o.sf ' on o.:0 0.?el0 'o.ll 0.J 0.

o,io-Jet.t6o.$0.J]

1.00i.0unt.0tr.0

l.@'

I= {-lt

lDo.tio.9a0,r9t{xl

1,0{ l,oct.06 qJr0.96 .,0J,0t ot9oJt r.o

l.tt.r1.01t-0tlt36

o.tJ0.9r.0E.o4t.et

-t/2Ittto

o..0 o.{t o.lt ojfQ.I. O.J1. o. 0;.4c: gJt ot O.l7ot .r , D.lt 0.2to- o fr-il o.lJ o.2l

LOI 1.00r.0l 1.00lr0l l.O0t.06 .l. r40

.o o-2:o51 'O,rt.r5 0,t]0.t r.ot0.J r-r,t

fE 't-01 r,.9? .0tr.fr2 t,06r-o+ 0.96.05 1.O10.96

0.9E

0.t5o.9Jt.fnLrx

f.0?

Jtl o.trr cJsI o,ti 0,llt0 .{ojt o.lt O-,r:0.t -019' o.r{0.19 0.72 th26.t olt o.;?onl o-10 0,r]

0.9t O-9r 1.00t.ol o.e+ r.d0fL99 0.99 l.o0t.0 .00

l.o0I =$04

o.tf-07-o3.oJ.e

0.1o.l0D.0i

w oJtI O::I 0'16J t 0-10to o.o

.0.1J0-1:9.tr0-t I0.08

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l$l Lot r.00,05 99 1.000.t6 ,01 l.0o.t.ot 0.99 [email protected] .ol l.oot, = lJo

1.00l.@1,00t.o0t-00

0...9. 0_59 ' O.1.2 Q.85o,1z 0J6 0.?J 0.950J5 fl-J{ o. l.oo-2r :2 -01 l.1y.7t o.n .14 .07

0.N0.2't-o.2ArHJ0.ot

o.lt o.7,0,:0 0.21r q.llD.{DO-lO0,o o-ot

1.2,IItl0

02t0-20o.t40-D9o-o7

o.J2o.2JIL7o-il0,m

0..to.lo.tJl.t7o.t2t' = 110

0.2?0.1 9o,1{oi0t0.06

o,:io.tt).t40.09o-?

.600J7It-to.5toJt

I1.0t.oot.00'1.c

0.tT,04

tlr-0JOJE

0,7I 0.t?0.?6 0.'Jo.Er l.sl.0l -o4t-tj t.o6

0.4t .JDoJ 9.{]'026 0J60-t ,0:?o-tJ 0J

03t oJ5qlt 0.1?0"t? .10o"il o-tt0-01 o-

ltz 0:i- :6I o"t8 .t92 0-u 0,rl5 o.qt 0.{Elo 0,060.06

l, = l]lr0.:.E 0.12 0.16 0,12 0.52 0.6t0:r o"zJ 0.2E 0J4 0.44 0.59o.t4 o"tt a.?0 0.2 aJ7 oJ60.09 0.t 0.J 0.t? 0J8 0.t40.? o-ot qo9 o.t] 0: 0.JJ

112 0:,r O.t o.tt o-t?2. o-r2 0.1:t 0.01 0.07. l (LoJ 0.06

0,?60-780.Elr.00l.J2

o2solr0-t.l0-0tt06

0:6o-19o.l.r0.080.06

r = 50t.mTOt-c.00.lr0o

oJ, 0.13 0.38 0.1s 0.55 0-61 0.802 0,2{ oJ9 oJ6 07 o-f} 0J30.t 0.$ a7 08 0.t9 0J9 0J60.10 .lr o.ll frt - 0t olt o.99o,07 o.Gr 0.0 0.t, G22 0J4 t-19

' .210.t?0.120.@. o.o5

0:t 027o-tr ol9o,t, 0.K0t 0.0ton6 0J6

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APPENDIXIV

Note:Please detach this sheet and attach withthe answer booklet

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