1a Permeability of rocks is one of the Jactors that affect the volume of water in a

river. Using a well-labelled diagram, explain how it influences the volume of theriver.

Study Figure 1 below.

Source: http://www.kaleberq.com/Dortanqeles/alava/topomao iDq

ldentify the coastal landform shown in Figure 1 and explain its formation

Choose and explain any three erosion processes from the following:

l5l

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161

b.

c..attrition.hydraulic action

.corraston

.solution

Figure 2 shows the Singapore River in 1960s and the same course of the river in

2004.

d. ldentify ihe type of channelisation shown in Fig 2 and discuss the impacts of such [8]type of channelisation.

ANSWERS

'1a. Permeability of rocks is one ofthe factors that affect the volume of water in a [6]river. Using a well-labelled diagram, explain how it influences the volume of theriver-

Award 1m for any ONE of the diagrams, 1m for annotation

- When rain falls on higher permeable rocks, there is high inJiltration ofrainwater into the the ground

- Less surface runoffflows on the ground- With lesser permeabile rocks, less water will seep into the ground- Greater surface runoff results

Figure 2

,u,oi,.,' f,i;;;"'1$@;- iWt*b-fwr,\tY:r:.,#Y q

I I i u,'--l r pt.riar LfJfr +

[1m for each poini. I\,4ax. -5m1

Study Figure 1 below

Figure I

SoLrrce: http://www.kale

ldentify the coastal landform shown in Figure 1 and explain its formation'

- Clifi. high. steep rock face alonq ihe coast- Formeiwhen waves repeateclly pound against a rocky coast

- itrif wear.ens tne rocks, causing lines of weakness to form in the rock

face- Ove, tim., the waves erode the coast to cut a notch along the lines of

weakness- The notch may be further eroded to form a cave

- fn" ou"rnunging part of the notch eventually collapse.with repeated

pounolng or ii,"-*"ues. The part of the coast that is left forms a cliff'

Choose and explain any ihree erosion processes from the following:

.a rition 'corrasion

.hydraulic action 'solution

hvdraulic action- force of last movinq water slronq enough

- ioo""n rocks and s;il which are dislodged and carried down the rlver

- river channel is eroded as a result

corrosion/abrasion* ]- r.olr.?rusr""ts are dragged along the river bed 9l 'iu"'gulk" -- -- the qrinJino aclion causes lhe river channel o widen and deepen as

r".1"-" ""J

i"lr are scraped off the sides and bottom and carried away

.com/oorianqeles/alava/toporna

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r

with the water- particularly effective during a flood when a river's energy is at its

maximum

attrition- the load which the river carriers collide with one another as they move- over time, the collision causes the materials to break down into smaller

pieces.- Larger rocks are slowly broken down and their rough edges smoothed

out.solution

- rain reacts with carbon dioxide forming carbonic acid.- As the rainwater falls into rivers, the weak acid dissolved the minerals

preseni in the rocks on the river bed and banks.- Eg. When a river flows over limestone, a chemical reaction occurs

beh,,r'een carbonic acid in the water and calcium carbonate in thelimestone.

- Caicium carbonate dissolves to form calcium bicarbonate which issoluble in waier (solution)

Award 2 marks for each process

Figure 2 shows the Singapore River in 1960s and the same course of the riverin 2004.

ldentify the type of channelisation shown in the Fig 2 above, and discuss theimpacts of this type of channelisation.

River Re-Sectioning [1]

Positive impacts (Max 4 mks):- Re-sectionlng is the widening and deepening of the river channel [1].- This increases the river's capability to hold water thus decreasing the

chances offlooding [1].- Re-sectioning also increases the amount of suface runoff from thesurrounding areas into the river [1/2]. As more surface runoff can now

tBl

Figure 2

enter the river, there will be lower chances offlooding [1/2].The river bed and banks may be smoothened by replacing the soil ofriver banks and bed with cement and granite [1]As there is now less friction between the water and the river bed and

banks, speed of the river increases allowing water to flow away withoutflooding the surrounding banks [1].

Negative impacts (max 4 mks):- lf re-sectioning takes place upstream, the volume of water flowing

downstream is increased [1].- The channel in ihe area downstream may not be able to contain the

increased flow of water and flooding takes place downstream [1]- Re-sectioning allows the river to increase its speed and energy'

resulting in more sediments being carried downsiream ['1].

- Overtime, build up of sediments results downstream causing thechannel to be shallower downstream, and flooding might take place [1].

- lt is costly to replace soil at the riverbed and banks with cement andgranite [1].

- lt is also difficult for re-sectioning to take place in a river with existingriver activities [1].

Figure 1a below shows a Hjulstrom Curve, which shows the velocity(speed of river flow) against the size of particles.

FlowVelochy r

mm per s€c

FMSS I\]IYE 2OO8

GEOG ELECTIW SEC 4 EXPRESS

a

eq 9-. n a ovo A _

Diameter of Sed;ment (mm)

Fis. 1a

Using Fig. 1a, explain how the process of,erosion' is influenced bv size ofload and river vetocity. I4l

Explajn, with the aid of relevant diagrams and examples, lggtransportation processes in a river. t41

Figure 1b below shows part of a river and its valley in the lower course

Y

Fis 1b

For feaiure labelled X OR Y

i identify the feature

ii with the aid of diagrams' describe the formation of the feature

FMSS lvfr'E 2008

GEOG ELECTM SEC '1 EXPRESS

ctFig. 1c

cI

ldentify and describe the coastal protection measure shown in Fig. 1cabove. Explain how this feature protects the coast. t3l

"Encouraging the groMh of coral reefs is a more effective form of coastalmanagement than the use of Seawalls."Do you agree with the statement?

---end of paper----

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IMSS T{\'E 2OO8

GTOG ELECTII,€ SEC 4 EXPRESS

Answers

1ai Fig 1a shows a Hjulstrom Curve' which shows the velocity against the size

of oarticles.tn"

'"rl"linl"o"*'"le the higher the speed needed 10 erode

For example, the particle srzes more tl.rln-i tt "u"h "" ""nd

require a speed of

;"#ftft;dm"ni;"" i" "to*

tt ut "taed

Pebbles (10mm) require a speed of

10Oomm/sec to be eroded . , , "^-*,-^^ ,itlriiiiiilllj, tjii"t" ot o stt' require a slower speed of about 1somm/sec in

order to be eroded#;;;;;;;;;; ;"e that very fine particles' from o 0o1 mm to 0 1mm' such as

iiliil"i !iri. 'ii"ri" "p""0 ot ,p to iooot*i""" in order to erode [1] as these

particles are highlY cohesive'

aiiiraction: Larger sized materials, like boulders and stones' are moved

il;;;i;# il.lli;g oi"iloing'"rons tne river bed durins floods or bv a rast

flowing river.

Saltation:Smallmaterials,likepebblesandcoarsesandparticles'aremovedffi;:;;; i;" ;;iius oi bouncing motions/are lifted up and dropped onto the

river bed over and over again'

Susoension:Fineparticles,suchaSsiltandclay'arecarriedbyfloatingalongtherive; without touching lhe river bed'

Solution: Soluble minerals, like calcium carbonate' is dissolved in the river water

and transPorted downstream

iir"rl i"i ""itroj"

oiagram three marks for explanation of2 processes)

Feature X:'r\Llio"ur" o""rt *nen a river twists and turns' and forms-hoop-like

;":i]::iiiril;;; irost prominent in the lower course or a river' As

"i"ii"tl j"i i6o*i,ion continue on the concave and convex banks

t"""""ii""ru i l"" t"ander may become more and more pron"yT:l:l:-iJ".!""""1"i"ii'oi ; nanow nect< 1t1 Euenlually the river breaks througn me

;".;"k;;'ll;;J ,hr";sh a straighL-channel lil l he meander is graduallv

:;;fd ffi;"',i* inJ is seiarateo t'om ihl main river channel forming

an ox-bow lake [1]I mark for diagrams

Feature Y:li["i in"r" i" n"ruv rain a river may rlood and overflow its !ii!":, ttle" t-n" nooo*ut"l.

"[reads over a larger area the water loses speeo

;il;i;ilft;"]5 irl wn"n t'" 'ii"' oesins to deposit its load the

rMSS N'['E 2008

GEOG ELECTIVE SEC 4 EX?RISS

heavier and coarser materials will be deposited first and lefi near thebanks of the river [1] while the finer and lighter materials such as silt andclay are deposiied further away. [1] After several floods, the continuousaccumulation of coarser materials on the banks of the river helps to raisethe banks higher than the floodplain forming naiural embankmentscalled levees. ['11 1 mark for diagrams.

ci Groynes are low walls built at right angles to the beach. [1]They prevent materials from being transported away bylongshore drift [1]. This enables the transported materials to accumulateon the updrift side of the groynes facing the longshore drift, thusprotecting the coast from erosion. ['1]

cii Level 1 (0-3m)

Brief or general description of how coral reef and seawalls protect the coast

Eg Coral reefs grow along the coast and they can weaken wave energy.

Seawalls can be built along the coast to absorb the energy of waves before iheycan erode away loose materials.

No relevant examples.

No stand on their effectiveness.

Level 2 (4-6m)

General descripiion of how coral reef and seawalls protect the coast.

Eg Coral reefs grow aiong tropical coast- Natural reefs can be conserved andprotected while damaged reefs can be restored.

Seawalls can be built along ihe coasl. These siructures absorb the energy ofwaves before they can erode away loose materials.

Suppoding examples given.

Eg Some corai reefs can be found along the coast of Peninsular l\,4alaysia. Someseawalls can be found along the coasts of Penin$ular l\,4alaysia.

l\,4akes a weak stand on their effectiveness

rMss t-{\.E 2008GEOG ELECTIVF SF,C 4 FXPRFSS

Eg Coral reefs are highly effective as they can weaken wave energy Similarly'seawalls prolect the coast from erosion.

Level 3 (7-Bm)

Deialled explanaiion of how coral reef and seawalis protect ihe coast-

I\,4any t[opica] coasts are protected by coral reefs which weaken wave energyNatural reefs can be conserved and protected while damaged reefs can be

restored. Artificial reefs can be created along the coast by placing

environmentally friendly and durable malerials such as steel or concrete on the

sea-floor.

Seawails can be built along the coast- These struciures absorb the energy ofwaves before they can erode away loose materials. Seawalls can be rnade ofconcrete, rocks or wood.

Relevant supporting evidence and examples given.

Coral reefs can be found alonq the east coast of Trengganu in PeninsularMalaysia. Seawalls can be found along the coasts of Penang and fi,4alacca in

Peninsular Malaysia.

l\,4akes a strong stand of their effectiveness.

Man-made reefs can be iust as protective of the coasts as naturally formed reefs

As they grow over lime, they form an effective barrier against \ /ave erosion Theycan also help io enhance fishing opportunities and serve as undersea barriers toreduce the impact of wave energy

Seawalls are especially effective in protecting cliffs from erosion. Ho\rever highlyerosive waves mean seawalls need constani maintenance io ensure lhey areeffective in protecting ihe coast.

FMSS N{\'E 2OO8

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2(a) The figure below shows 4 river in the upper course.

(t

(it

Describe the riverprocesses that are takjng place along this seciion ofthe rivcr.to r esull in the lonration of thc rorse.\{arerlall.:rrc r co,rm,," ".r.*"i"i"ain rhe upper ,or,,"e or r rc rire,. t siiqueil labeled tlragrrn...horr hou

" r rerrcll. ,re' r'orm.d.

"'" ' -' "":;i

(b) The figure below shows a river in the lower course and the surounding flood plaitr.

(i)(ii)

Explain why flooding occu6 in the arca.

lfl?T"Yr::H:'. *" seltlenents atons the river's

L4)

l2lflood plaim despite the

(iir) Assess the effectiveness olthe flood management

shown in the figure.

st-ategy used in the area

[g]

cr IANCYAT\C SECONDARY SCEOOL

or*sr srMES'rn"{ sx {MlNATION Z0lJlt

Geography Elcctiv€ (2192/02)

2(ai) nescribe the v€r processcs that are takrng place alongthis s€ction oIthc river to rcsultin thet5l

form:rtion of the gorge

- .uer rs fast flowrng. high energv le"et

- ra.rd eroson txking Place.",,". "" r,'aL""t" a' ior md r e o'iolal proce\'e<

;;:l; i;; .; ;;';;. *.':on oI he nrer bPd + r D d

- d;€p, nanow. \teep-sided \aLle)s to'nr

./-ii\ w.t'€ffa s are I common feature iound in the upper course ofth€ river' usi"e w"trlabel€d ,u,"'""' ii""',-i'r'"" ho{ sarerfars :ri'e rormed'

Dra-grams. well labelled = 2 maks

Exp lrnation : a ma rkq rult of faulring and/or erosion along rock of different resistance)

(Accept fomahon ol waterfalls aq a r€!

21b) The ligur€ below shows a riv€r in the lofl€r course and the surrounding flood plah'

lr\ino evidence trom rhe ligure. I4lii1"'or"i" "U floodioe ottcn occurs itr the area" - l*' ",r'l

r"""-J\F los "1e€) e\e'

'low-lYing area, fiar Land

deDosirron rs raking Plrce

'l"i'".','o'"r *' "r

cndrler ri\erclannel r"h"lro*er

' i'"'"^" l' *r"'" i''t "ter a rain) will result in flooding

- " *"lt"tl"" ln"v 1""" taken pLace in the upstream

noor nood managemenr "raletsi"' t 'ter

fiI ,'i""."' t',. "i ":i'e' arar Ege br'in dric' e 'lr

in a la'ge \orume or ualer

(i expl:rin whv settlemcnts are common dong th€ river's flood plains l2l

'.on is allu\ral soilvefl sLritable lor growing rice

',.ll,"i,iii "i' "1"'a '.irceor$drer tor imgarron dore{ic dre rran\pon

n"ta trP" '*" rr"-t* L!(en bY larme^

(iii) ass$s the effectiveness or th€ flood mmag€m€nt strategv used' I8l

t e\el I (0 - lm)'';,..''h;''''eg'"'""hotrnilre figu'ees buildrle d)le'andleree'

- r.i"nu a"t";1"' d'" uses ofdvkes andlevees

' No n;ntion ofiheir effectiveness

Level2 (4 6rn)

Identjfi es the straiegres

ri."u'''" a-""' -" Ine) p'F!'rr nooJ'

- in"'i'i" t'''i"'"r'or're'czTe'hod'orfloodpre\en'iorbnerL\

Level3 (7 8m)

' ldentifies the strateges

o1'."u't "

a''''r' 1"" rrev pre err nood'

- id*,1;;;;i;;;i;t"; ihe li;tauons orthe"e I nrethods or flood'pre\enrron',,,fthe stmtegr€s used

- ;"":;' ';' ''"" ' ce bJ 'hoqrrs 'n he candrnares oprnion rhr r'reranc( '

(a) Study Fig. lAwhich shows the fonnation offeatures X andY.Identify and describe, with the aid ofwell-labelled diagrams, the fomation offeatures X and Y. 16l

Fig. 1A

(b) Study Fig. 1B which shows a coastal area.

Fig. 1B

(i) Explain, with the aid ofwell-labelled diagams, hovr' featue D is fomed. l8l

(ii) Explain what may happen to featwe D over time. t3l

(c) Evaluate the elfectiveness ofplanting mangroves along the shore as a coastalprotection measure.

ANSWERS1(a) Sludy Fig. 1A which shows the formalion of featu.es X and Y.

ldenti! and descrihe, wirh thc aid ofwell labelled diagnns, the formatio. of features X and Y.

21n- diagrams 4 m- description

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X - headland

1-2-

Some coasts are made of rocks with different resistance to erosionThe less resistance rocks such as chalk, erode faster, compared to themore resistant rocks like graniteThe different rates of erosion of the rocks along a coast produce alluneven coastlinethe less resistant areas of rocks curve inwards as they get eroded away bythe wav€sY is eroded faster - bayTh€ areas made up of more resistant rocks will protrude out form thecoastlineX is croded more slowly - headland

Study Fig. 1B which shows a coastal area.

(i) Explain, with the aid ofwell-labelled diagrams, how feature D is formed-

4-

o)

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r

2m - diagram 6m description

S A ldlifiBr rtri i,.rhj;h &dry!*rdIr&: o,il, [iif.

, rlM!!i: fu nrkietrie.!ii

D- spit

1- lolgshore currents transport sediments parrllel to the coast2- when the lo[gshorc currents encounter a bay or a bend in the coast rvithshallow sheltercd water,3- the currents get weaker and the materials they carry will be deposited inthe direction ofthe longshorc drift4- O,ver timc, the accumulation ofmaterials will result in a long, narrow ridgeof sand.5-6-

with one end attached to the mainlatrd andthe other extending illto the open sea.

(ii) Explain what may happen to leaturc D over time.f- iftherc is no change in th€ wind dircction, l3l2- the spit may extenal seawarals, then it may eventuallyjoin the islandand form a tombolo (refer to no.3 in djagram above)3- ifthere is a change in wind direction r"he spit may extend ir anotherdirectionil- or it may become curvcd and crooked

1 (b)

:a0 :l:li,l:ir :r:l l.ibi)rf i :o;ii. lrryrfiErlri,apr+ Bil

l(c) Evaluale the efl'ectiveness ofplanting mangroves along the slore as a coastal

protection measure.

Level 1 Attswers are tmbalanced, brief and lacking in ntnborotion-\o .uppodcd cu, Ltivcn,

"-', ot ,inple ,tarmenr\. c R. horked ,

b,rr,r.One or two suggestions ofproteclive measues, bul no detaile.g. hard engineeringsoft engineeringPlanting ofmangroves

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Level 2 Measures mentioned, may be no -ore than giiiiiQ ofiiiiis;ivery brief des cription.Briefstatements of elfectiveness. e.g. 'planting oJ mangroyes has helped toanchar trees in the muddl) soil '

e.g. hard engineering : construction of structures, such as seawalls.breakr,r aters . groynes and gabionssoft engineering : applying knowledge ofnatuml processes to stabilise thecoast and reduce erosionPlanting ofmangroves : soft engineering

I1-6!,

Level 3 Candiddte ,explains at Lost I bnneStt oo,ll problem oJiach st orngy

co mpeten t b wi t h e lab o rdtio n.Candidate makes a sLLpported stanclAttempt to cohpare beneJits and/ or problems are well supported with

Given measure anil 2 other meas res nohted with some detail, e.g.Planting of man$oves : many of the mangrove trees have prop ro-ots orkneed roots that anchor the trees fuT y in the muddy soil. ihese rools alsobind the loo.e soil. and protecl ir lrom erosion.Clear stateme ts of degree ofelfectiveness, e.g is effective in preventing coastagainst erosion by waves and wind but requires the cooperation ofthe licalpeople living in the area'

Given measure : mangrol)es and 2 other measLresNlention 2 other method -e.g, hard engineering : construction ofstructures,

: +ve a.nd ve points.

such as seawalls,breakwate$ , groJmes and gabionssoft engineering : applying knowledgecoast and reduce erosion

ofnafural processes to stabilise the

EffectivePlantilrg qfmangrove is effective itr preventing coast against erosion bywaves and wind

l7-81

il"5of lba-""gt * r*". ha prop rool\ or kneed roots lhat :rncbor

the trees firmly in the muddy soilThese roots also binal the loose soil, and protect it from erosiol

Ileffective and comparisonslEFng -ungro.,es are fragile, mtrngroYe pltntirg exercises

cooperatior of the local people liYing in the area

e.g.ihe local people need to be mindful not to let animals like

and graze on the new rlangroves- may take up land leeded for cultivation

other methods : giv€ advantages trnd disadvantages :

Breakwaters built off the coast parallel tn i1-

+ve : Made of graniteCreates a zone ofshallow water befrYeen itself alrd the coast,

waves will break agaitrst it before reachilg the coast

-ve :Unable to provide complete protectionLeave certain areas ofthe coast unprotectedExpensive

require the

goats elrter

so that

Seawalls, Groynes, gabions :Seawalls r

J[]-iud" of"oo".ete, absorbs the energy ofthe waves and protects th€

coast against strolg waves, €specially during storms

- Lasts longer (maintenalce not very lecessary)

- Helps to protection coast from erosiotr, but also allows fordeposition to take Place.

- Protects coast .gainst longshore drift

-ve : exp€nsive, in the long run, it may not protect a coast from erosion'

As waves break agaitrst the seawall' the energy from the waves is

redirected downwards, to the ttase ofthe seawall' resulting in a strong

backwash. The backwash Nears away the base ofth€ sea\aall, causing itto weaken and colhpse.' protects only a certain stretch.

Gabions : can be easily destroyed by polverful waves during storms and

the wir€s rust easily

Sfahilisins salrd dunes+ve l protect human proPertY likeerosion and flooding from waves

-ve : human activities on the dunes

houses and roads against coastal

have damaged the vegetation and this

causes the saDd to be blown inla cove ns the roads and buildin

causing the entire town to be abandoned.

Beach nourishment:Bringing sand to the beach.- expensive! lasts for only 10 years- tongshore drift will move it, needs replenishment

(a) Describe how tropical rainforests and tropical monsoon forests differ in theradaptalions to their environmenls ln tenns of t8l

TRT' TMFStr'Llclure 5 vertical layers; more variety

ofplantsEmergent layerCanopy layerUnderstorey layerShrub layerUndergrowth layer

- Topmost layer is the emergentlayer where trees grow above

- the canopy to obtain as mushsunlight as possible

- undergrowth layer which issparse as there is little sunlight,block by the thick fotiage ofthecanopy layer ; where fem,mosses, fungi and other smallplants live as they do not rcquircmuch sunlight to grow,

3 v€rtical lavers

- Canopy layer-

- Understorey layer- UndergroMh layerCanopy Layer(25 to 30m)

-Trees are shorter and has lesser layers

-do not forrn continLrous layer and morespread out than those in a tropicalrainforest -'open canopy'- presence ofparasitic and non parasilicplants in this 1ayer.

> due to the seasons:> lack of waterduring the dry seasons does not allowtees to grow great heights)crowns ofthe canopy layer do notinterlock one another as the trces do notgrow as closely together.

UnderstoreyLayer (15m)

Undergowth (0-6m)

t dudng the wet season as therc is morewater & more sunlight can pass throughas the crowns ofthe canopy do not fom a

continuous laYer

) du.i"g uFaty s"us- us ttrer. ii tu.toi warer

Di\ ersiry Righ biodiversjtv-Consists of1nany species ofplaDis and trees

One hectare of land has up to 750specles oftrees aDd up to 1500

ies of other

F. u., 'p..i.t c,t plrnG - .. -

--About 200 species ofplants can be lbundin one hectare ofthe lorest-trees are hardwoods-tlees are con]Inercially valuable

Densiry - extrernely dense becaus.ofniniltemperatures and rainfal I

abundant plant growtTbi jesiiGIthan the tloprcal rainforest-dense forest llke the tropica] rd;forestounng wet season-forest appears spalse) inconsistent rainfall) to wirhstand the penod ofhiehmi nf.ll.)

"al rs used a. fueluood. sandat*ood is

Broad, waxy with drip tips waxy *ith drip rlps- Bamboo has narrow leaweq) shed their lea\es during rhe dry seas,_ruto nnnrruze loss of water throushtmrlspiration.> leare( willgror qrrickJy agrir durinvlhe uer season) to drain offwaler easily during the wetseason to prevent the groMh olharmfulbacteri,) to minimize the loss ofwater through

'to' :*0,,t,t 2 wh,ch.ho*. rhccro.-,ectron ofa ri\ er channel,, roslrrry learures cnd describe,lvith the aid ofwell_labelled diagrarns. thelormation offeature X_

lm - diagram 4m_description

X - levees

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t.-

't- When there is hearT rrin! a river may overflow its banksThis caus€s the lard on either side of th€ river to be floodedwh€n the water recedes, the river leaves behind alluyium on thebanksthe coarse sediments are deposited closer to the river's edge,orer time forming raised banks called levees1-

(ii) Discuss the advatrtages and disadvantages ofliving near these features.

Advantages (2 m)1- the levees may 4ct as protection to prevent water fiom river

orerflowing onto lhe lloodplain2- floodplain nay bc fertile, suitable for growing crops3- settlemenls may de\elop oo {he floodplains

Disadvantages (2 m)1- the levees may break and water may overflow2- the floodplains may get IIooded, crops trnd buildings are thus

destroyed by the floods

(c) Assess the effectiveness ofthe dykes as a method ofbant protection.

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Level 1 Answers are unbalancn,l, bri"Tar@No sLtpported elfectireness, or simple stateme ts, e.g. ,it warked,, ,it was a lotbetter'.One or two measures mentioned.Measurcs me tionetl, -oy Itero^@brief description.Briefstdtenents of elfectiveness. e.g. ' the dykes prerent oyerflow'One ot more measurc\ mcnti\ned.Some dttempt L^ made to conlpare the bene/its and/ or problem, sLtpported b)j

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I1-61Level 2

Level 3 Cttftdidate e4)l.tifts at least 1 benelit and I proUen oJii stit"g-c o tipeteht ly w it h e labotution-Attehpt to compare benefits and/ or ptoblems ate well supported withe&planation.Given measure and 2 other measures ,tamed with sofie dctutitI len! :4!:!:!!:J! delt ?? at qtfpctit eness. a.g is el1-eclir e in prer enliDe oan,ls

t7-8t

@intenance of the structure is

hieh.

Dvkes

Effective- fi-alts of sand, stone or concrete built along rivers that often overflorl their

banks- prevent overflot- increase the capacif] oflhe ri\er lo hold waler

- ther€fore reduces the chances offlooding

Ineffective-"otrtioo"t ttuita op of sediments on the river bed

- channel becomes shallower- causing water levels to rise higher than the dyke walls

- river overflows- higher dykes have to be built regularly- sciimenis have to be dug up and removed from th€ nver on a

regular basis- expensive

Others: gabions, revetmcnts, planting of vegetatiol

Gabions or revetments- structures of small rocks contained in wire cages

- used to divert th€ flow ofwater from the river banks to the ceqtre

of the channel- protects the river banks from being eroded

- ihis reduces the amount of sediments flowing into the river' thus

increasing th€ cnptcity ofthe river to hold water

Ineffeclive apd comParisoDs

- "otttiouut

buitO up of\cdimeDt' oo tbe river bcd

- channel becomes shallower- river overflows- expensiae- cages may become rusty

Planting of vegetatronEffective

- plalrting ofvegetation along a river can also protect river banks agailsterosion as the roots oftrees and other plants hold the soil together lirmly

- vegetation slows down the rate ofsurface runoff- preventing large amounts of water from enteritrg the river at any one time

Ineffective- Young plants ar€ fragile, planting exercises require the cooperation ofthelocal people living itr the areae.g. the local people need to be mindful not to let animals like goats etrter andgraze on the new vegetation- may take up land needed for cultivation, agriculture

River A River B

Amouni of rainfall (mm) 20 20

Gradient of river Steeo Gentle

Texture of river bed and bank Smooth channel Rouqh channel

Depth of river channel Deep channel Shallow channel

(a) Figure 4 shows the characteristics of two rivers.

Figure 4

With reference to Figure 4, explain which river would have a fasterspeed of flow.

(3)

(b) With the aid of a labelled diagram, describe the processes ihal lead tothe formation of an oxbow lake.

(7)

(c) What are some problems thal may occur after channelisation has beencarried out to prevent a river from flooding? (3)

(d) Photograph A shows t\/o coaslal features caused by erosion.

Two coastal features caused by erosion

photograph A

and From Photograph A, identify the coastal landforms marked X and

explain how they are formed.

(e) Evaluate the effectiveness oftwo soft engineerjng measures usedprotect the coast.

(a) Figure 4 shows the characieristics oftwo rivers.

Y

(4)

io(8)

Amount of rainfall (mm

Gradient of river Gentle

Texture of river bed and bank Smooth channel Rouqh channelDepth of river channel Deep channel Shallow channel

Figure 4

With reference to Figure 4, explain which river would have a fasterspeed of flow.

(3)

River A is likely to be faster flowing.- This is because wiih river A is flowing from a steep gradient which will causethe speed of the river to be high due to a stronger pull of gravity.- The smooth texture of the channel means that the speed is speed of flow ishigher as ihere is lower friciion betvr'een water and lhe channel due to theabsence of obstacles.- A deeper channel means a larger cenler which means a higher speed offlow. This is because the center portion of the river channel is where the riverwould flow the fastest.

(b) With the aid of a labelled diagram, describe the processes thal lead tothe

formation of an oxbow lake. (i

- Over time, the meanders of a river become more pronounced causing thehnro Concave (outer) banks of the river will shift closer together due to erosion

taking place on the concave banks.- Eventually, the Concave (outer) banks will meet. The sediments deposited

on the inner bank will dam up the waier in the cut-off- The river flow will be straight again, leaving a new feature known as the Ox-

bow lake.

Reserve 4m for labelinq

Formation of Ox bow lake

li rl\. i'{cetrl rrlun&rt'

-i$'ilrirll, l)ri!* mdsl hjhld $ltrl1 ir*ir.tr

(cl What are some problems that may occur after channelisation has beent!' ;ft;';,ii; il";;ia river trom'ttoooinsr (3)

- lncreased speed after channelisation result in llooding downstream

- ;;;;;l;"-ti;;.uses speed of river 1o increase Hence' sedimenls carried

to sea resultrng in less sunlight reaching the seabed ..jcn"igi"g ih; ""rise

of the- river and lining the natural banks of the river with

concretesuTfacesinchannelre-sectioning'alsoaffectplantsandanimalsaStheir habitats may be destroyed'

(d) Photo A shows two coastalfeatures caused by erosion

PhotograPh A

From Photograph A, identify the coastal landforms marked X and Y

andexplain how they are formed. @)

- X: Headland, Y: Bay.- Some coasts are made up of rocks with different resistance to erosion whichproduces an uneven coastline.- The part of ihe coast made up of less resistant rocks such as chalk' curve

inwards as ihey get eroded away faster by the waves to form bays.- On the other htnd, the areas that are made up of more resistant rocks such

as granite protrude out from the coastline as they are less easily eroded to

form headlands.

Evaluate the effectiveness of two

protecl the coast.

soft engineering measures used to

(8)

(e)

- For example sand which has been carried away by longshore drift toanother area along the coast can be broughl back and deposited on theeroded beach.- However, the effects of beach nourishment usually last for only aboutten years and the cost is especially high because beach quality sand isvery expensive and regular maintenance is required.

- The growth of coral reefs in shallow seas is another measure used to protectcoasi

- These reefs protect beaches against coastal erosion by reducing thespeed of waves approaching the coast, thus reducing the impact ofcoastal erosion.- However, human activiiies like dynamiie fishing, sand mining and landreclamation have desiroyed coral reefs.

- The success of this measure in the long run depends on thecooperation of many groups of people, including industries, fishermenand the governmeni in ensuring the coral reefs are protected and arethriving.

Any two of the above factors with elaboration and evaluation

(a) Figure 4 shows the characteristics of tvvo rivers.

Figure 4

With reference to Figure 4, explain which river would have a fasterspeed of flow.

(3)

River A is likely to be faster flowing.- This is because with river A is flowing from a steep gradient which will causethe speed of the river to be high due to a stronger pull of gravity.

River A River B

Amount of rainfall (mm) 20 20

Gradient of river Steeo Gentle

Texture of river bed and bank Smooth channel Rouqh channel

Deoth of river channel Deeo channel Shallow channel

- The smooth texture of the channel means that the speed is speed of flow is

higher as there is lower friction between water and the channel due to theabsence of obslacles.- A deeper channel means a larger center which means a higher speed of

flow. This is because the center portion of the river channel is where the dver

would flow the fastest.

(b)the

With the aid of a labelled diagram, describe the processes that lead to

formation of an oxbow lake. Q\

- Over time, the meanders of a river become more pronounced causing thetwo Concave (outer) banks of the river will shift closer together due to erosion

taking place on the concave banks.- Eventually, the Concave (ouier) banks wiil meet. Theon the inner bank will dam up the water in the cut-off

sediments deposited

- The river flow will be straight again, leaving a new feature known as thebow lake.

Reserve 4m for labelinq

Formaljat alQx_bew la.Ke

Ox-

Npillioil l.rt*{ |lr!,&ditfi oil d]r'r., r]i!:x"rr

l!r!,r! liilcl rllilt Mratdrr

I'ii }lj,f{rllr hjn{ tiddft&x lic !11

*ghlq\*tii

(c) What are some problems that may occur after channelisation has beencarrjed out to prevent a iver from flooding? (3)

- lncreased speed after channelisation result in flooding downstrearn- Channelisation causes speed of river to increase. Hence, sediments carriedto sea resulting in less sunlight reaching the seabed.- Changing the course of the river and lining the natural banks of the river withconcrete surfaces in channel re-sectioning also affect plants and animals astheir habitats may be destroyed.

(d) Photo A shows two coastal features caused by erosion.

Photograph A

From Photograph A, jdentify the coastal landforms marked X and Yand

explain how they are formed. (4)

- X: Headland, Y: Bay.- Some coasts are made up of rocks with different resistance to erosion whichproduces an uneven coastline.

- The pari of the coast made up of less resjstant rocks such as chalk, curveinwards as they get eroded away faster by the waves to form bays.- On the other hand, the areas that are made up of more resistani rocks suchas granite protrude out from the coastline as they are less easily eroded toform headlands

(e) Evaluate the effectiveness of two soft engineering

protect the coast.

measures used to

(8)

Level1(1-2m) Describes one/two measures used to protect coast wiih no

evaluation of effectiveness.

(3-5m) Describes one/two measures used to protect coast with briefevaluation of the measures.

Evaluate one measure used to protect coast with detailedevalUation.

3 (6-Bm) Explanation of two coastal proteciion measures and detailedevaluation of two coastal protection measures

- Soft engineering measures involve applying knowledge of naiural processesto stabilise the coast and reduce erosion.

- One of these measures is to stabilise coastal dunes.

- A coaslal dune is a ridge of sand piled up by wind on the coast, whichact as barriers along the coast protecting human property from coastalerosion and flooding.- Coastal dunes may be stabilised by planting vegetation like marramgrass, which prevents the sand from being blown away.

- While the vegetation can stabilise the coastal dunes, they cannottotally prevenl erosion along the coast- ln order for dunes to be stabilised in the long run, human activitiessuch as property development and recreational activjlies need to beminimised along the coasts.

- Another measure is by planting mangroves along the coast to protectagainst erosion by strong waves and winds.

- The roots of the mangroves bind the loose soil and prevent them frombeing washed away.- During the 2004 lndian Ocean Tsunami, places with mangrove forestssuch as the coastal areas of Bangladesh suffered less damage.- For mangrove protection of the coast to work, the cooperation of localpeople living in the area is needed.- As young mangroves are fragile, the local people need to be mindfulnot to let animals like goats enter and graze on the new mangroveplantalions.- lt also takes time for the plants to mature and offer more protection forthe coast.

- Another measure is beach nourishment which is to add large amounts ofsand to a beach that is being eroded.

- For example sand which has been carried away by longshore drift toanother area along the coast can be brought back and deposited on theeroded beach.- However, ihe effects of beach nourishment usually last for only aboutten years and the cost is especially high because beach quality sand isvery expensive and regular mainlenance is required.

- The groMh of coral reefs in shallow seas is another measure used to protectCOAST

- These reefs protect beaGhes against coastal erosion by reducing thespeed of waves approaching the coasi, thus reducing the impacl ofcoastal erosion.- However, human activities like dynamite fishing, sand mining and landreclamation have destroyed coral reefs.

- The success ofthis measure in the long run depends on thecooperation of many groups of people, including industries, fishermenand the government in ensuring the coral reefs are protected and arethriving.

Any two of the above factors with elaboration and evaluation

Question 1: River and Coasts [25 marks]

Study the photograph below which shows the course of a river during winter.

Using evjdence from the photograph, explain howthe volumeof water will change as [2]spring approaches.

Figure 1 below shows ihe amount of rainfall that is recorded for three basins on a [6]particular day. Based on the information given, explain why the discharge for thethree basins will be different even though the amount of rainfall received js the samefor all three basins.

Basin A Basin B Basin CAmount of rainfall (cm) 100 100 100Duration of rainfall fmin) 30 20 30Presence of veqeiation Yes No Yes% of oorous soil 50 30 80

Fig. 1

With the help of a diagram, explain the formation of a delta. t41

Figure 2 below shows part of the south coast of UK.

F\9.2

Label coastal features Y and Z.

Explain the formation of Y and Z.

Evaluate the effectiveness of river channelization strategies

K'Y

ffin.r;!€-!.!f.:i

haid rock

sofl aock

i)

ii)

121

t31

t8l

Map to show ta.t ofthe soqth caas! 3{the [,,K

ANSWIRS

Question 1: River and Coasts [25 marks]

a Study the photograph below which shows the course of a river during winter.

Using evidence from the photograph, explain howthevolumeof water will changeas [2]spring approaches.

As spriDg approaches, the snow will melt [1] and this itrcreases thc volume of tvater irr thefiver lll,

Figure 1 below shows the amouni of rainfall that is recorded for three basins on a [6]particular day. Based on ihe information given, explain why the discharge for thethree basins will be different even though the amouni of rainfall received is the samefor all three basins

Basin A Basin B Basin CAmount of rainfall (cm) 100 100 100Duration of rainfall (min) 30 2A 30Presence of veqetation Yes No Yes% of porous soil 50 30 BO

Fig 1

Rivcr discharge is aflccted by amount and duration of rainfirll, presence of vegetation, size ifdrainage basin and type of soil. Althougll the amount of rainfa]l is the same, river dischargcrvill differ due to other factors such as duration ofrailfall, prcscnce of vegetation and typc ofsoil. [1]

The longer the duration of rainfall, the higher thc intiltration rate, lower thc surlace runoffand Iower rivcr dischrrgc. I1l

Thc presence of vcgctation will incrcasc thc infiltratioB rate; decr€ase the surface runoff andleads to lorver vcr dischargc, I1l

The more porous the soil, the higher the infiltration rater thc lowcr the surlace runolT andthe lower the river discharge. [1]

Basin B will h:1ve the highest river discharge [1] as it has thc shortest duration of rainfall,there is no vegetation alrd the soil is least porous.

Basin C rvill have the lowest dver discharge [1] as it has a long duration of rainfall, there is

vegetation and the soil is very porous.

With the help of a diagram, explain the formation of a delta.

When a river etrters a lake or sea, its speed decreases.Hence, the sedimeots that it carries are depositcd atthe river mouth. [1] The main river branches out intomany distributaries [1], as the sedimcnfs deposited atthe river mouth block the flow of thc main river. I1lOver time. rs sedimelrts accumulatc at the rivermouth, a delta is form€d. J1l

Figure 2 below shows part o{ the south coast of UK.

t4l

E hard rock

ll -a.cr'.:: s€niment

i) Label coastal feaiures Y and Z.

Y - Headland and Z- Bay

ii) Explain the formation ofY and Z. I3l

Somc coasts arc made up of rocks with different resistance to erosion. lll The less resistantareas of rocks are crodcd away quickly and this results in the land curving inlvards, forming

l2l

M3+r ro showpartorLc southco.stofthe UK

up of more re.istanl rocLs will protrude outheadlands. lll

e Evaluate the effeciiveness of rjver channelization strategies. t8l. Level t: 0-3 marks. poor answer quality. Explanation is limited. Evaluation is too simple

' flarnpler are ! ery general o. indccurale

. Level2: 4-6 marks.. Some knowledge showr but lacking depth. Some points explained but with miising steps. Examples may be relevant but lack det;ils

. Level3:7-8 marks. Good answcr.. Good Knowledge shown. Mo.r expecred point\ e\plalned rar leacr I poinrs are giren). Boib .ides olargument considered. PJa. e^pecrfic eramples are gi\ en.

River Charnelization Strategies:River Re-alignmentRiver Re-sectioningBanl< ProtectionPlanting ofVegetation

bays. [1] The areas madeThese areas are known as

from the coastline-