understanding our natural world - st marys newry€¦ · understanding our natural world the...

Understanding Our Natural WorldThe Dynamic LandscapeLearning outcomesIn this theme you will learn:● what a drainage basin is● what changes occur along the long profile

of a river● how waterfalls, meanders and floodplains

are formed● how the coast is shaped by waves● how coastal landforms are formed● why floods occur● how rivers can be managed● how to evaluate a river management scheme● why coastal defences are needed● to evaluate the coastal management strategies

used in an area of the British Isles.

UNIT ONE

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CCEA Geog-U1a.qxd 21/08/09 08:21

The Dynamic Landscape

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The drainage basin: a component ofthe water cycle● The characteristics of a drainage basin Water is a critical resource. The water that is most useful tohumans is fresh water, although this only makes up 2.8% of allthe water on the planet, and only 0.1% is stored in rivers andlakes. The rest of the water on land is stored in ice sheets andglaciers, or in the soil and deeper down in the ground. The totalamount of water on our planet never changes: in other words,none arrives from space, and none is lost to space.This is called a closed system. The water on Earthcirculates between the sea, land and air (stores),being recycled in a natural process known as thehydrological cycle (water cycle).

On the land the water is stored on the surface aslakes and rivers. Each river is contained within itsown drainage basin – the area of land drained by ariver and its tributaries. The boundary of a drainagebasin follows a ridge of high ground, known as thewatershed. This and other features of the drainagebasin are summarised in Figure 1.

● The components of the drainage basincycle and their interrelationships

The amount of water within a single drainage basin can vary, as ithas inputs (from precipitation) and outputs (fromevapotranspiration). So this is an open system.

Simple open system of the drainage basin:

� Figure 1 A generalised drainage basin

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SourceHigh ground

Watershed

Main river channel

Confluence

Mouth

Tributary

Drainage basin

InputsPrecipitation

OutputsEvapotranspirationFlows out to sea

Flows from store to storeOn and in vegetation SurfaceSoil (unsaturated)Ground (saturated)River channel


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Water enters the drainage basin system asprecipitation. This may be any form, such as snowor rain. Most drainage basins have somevegetation. The precipitation may be caught onthe leaves of plants. This is called interception.Generally, it is greatest in summer. From thesurface of the plant, the water may be evaporatedback into the air, or flow down the stem of theplant to reach the ground. At this point the waterhas moved from the store in the vegetation to bepart of the surface storage. If conditions are right,it will then seep into the soil. This process iscalled infiltration. Soil normally has small pocketsof air called pores, which allow the water to getinto it. Once in the soil, gravity will pull thewater downwards and it will move down throughthe soil as through-flow, until it reaches the water table, where all the pores in the soil, orrock, are already full of water, so it cannot moveany further downwards. Instead it now flowslaterally (sideways) into the nearest river asgroundwater flow.

Any water that hits an impermeable surface, with no pores,such as tarmac, cannot infiltrate the soil below. It simply flowsover the surface as surface run-off into the nearest river.

Although some precipitation can fall directly into the river,most water reaches a river by a combination of surface run-off,through-flow and groundwater flow. It takes water the longesttime after falling to reach the river by groundwater flow, since ithas had to flow through so many stores to get to the riverchannel.

1 In your own words, define the following river basin terms:drainage basin, watershed, source, tributary, confluence, river channel, mouth. You can get some useful help at:www.revisioncentre.co.uk/gcse/geography/drainage_basins.html.

2 Draw a flow diagram that shows one input, two stores andtwo flows within the drainage basin system. Check out:www.bbc.co.uk/scotland/education/int/geog/rivers/drainage/index.shtml.

3 Why does the total amount of water falling as precipitationnever reach the river channel? Give two reasons.

4 Why are environmentalists strongly against polluting rivers andlakes?

5 What effect might the building of urban areas have on thedrainage basin cycle?

Get Act ive

� Figure 2 The drainage basin system

Precipitation

TranspirationEvaporation

Infiltration

Unsaturatedsoil and rock

Water table

Saturatedrock

Soil moisture

Percolation

Through-flow

Groundwater

Interceptionby vegetation

Surface run-off(overland flow)

River carryingwater to the sea

Surfacestorage

Groundwaterflow

Key

InputStorageFlow (transfer)Output


Measuring the Glendun RiverVarious fluvial characteristics are measured atregular points (every 1 km) along the GlendunRiver. This type of sampling is called systematicsampling and it allows the investigation ofcontinuous changes as distance increases fromthe source of the river.

A group of pupils investigated this river.Figure 3 below shows what students measured.

How are these things measured?

WidthThis is measured by placing one end of ameasuring tape at one side of the river channel,then pulling it out to the other side of thechannel. The distance is the width of the river.

DepthThis is completed using a metre stick. The stickis lowered into the water every 10 cm, and thedistance from the top of the water to the river

River processes and features● Glendun RiverTo investigate how a river can change downstream, it is possible to examine a local river like theGlendun River in Co. Antrim. The location of this river is shown in Figures 4 and 5 on pages 6–7.Any river may be divided into upper, middle and lower courses.

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� Figure 3 Aspects of a river that can be measured

v

w

d

w = width v = velocity d = depth

width � depth = cross-sectional areavelocity � cross-sectional area = discharge area

bed gives the depth of water. An average of allthese readings is taken.

DischargeDischarge is the amount of water passing anypoint in a river in a certain time, normally givenas cubic metres of water per second (cumecs). Itis calculated by multiplying the cross-sectionalarea of a river channel at a certain point by thespeed (velocity) of the river at the same point.

The cross-sectional area is obtained bymultiplying the width of the river by the averagedepth. The speed (velocity) of the river isrecorded using a flow metre that when dippedinto the river gives a digital reading of the speedof flow in metres per second.

LoadThe load of a river is the material it is carrying,ranging from small sediment to large boulders. Itis very hard to measure the size of the load insuspension, so instead, we can concentrate onthe load lying on the channel bed – called bedload. This load is measured for size androundedness. By measuring the longest axis of 15random samples at each point an idea of the sizeof the load is obtained. Each stone is then givena rating for roundedness.

What were the results?To help see the overall trends, here is a selectionof results obtained from the Glendun. Theyrepresent the three courses of this river:

Upper course Middle course Lower course(Station 1) (Station 11) (Station 16)

Width (m) 2.7 10.4 14.2

Depth (m) 0.14 0.33 0.46

Discharge (cumecs) 0.08 0.2 5.1

Load long axis (cm) 26 12 7

Load – roundedness angular sub-angular rounded


To help understand and explain the results collected read theinformation about the processes a river carries out – erosion,transportation and deposition, pages 9–10.

Going downstream from source to mouth, it appears that theGlendun River gets wider. At Station 16 (16.5 km from thesource) the river is just over five times the width it is at station 1,only 1.5 km from the source.

The river also appears to get deeper. At the station in the lowercourse the river is 32 cm deeper than it is in the upper course.

This can be explained by the fact that there is more lateralerosion and vertical erosion occurring downstream from thesource.

The enlarged river channel size downstream relates well to thepattern of increasing discharge. Because discharge is calculated bymultiplying the cross-sectional area of the channel by the river’svelocity, then it follows logically that as cross-sectional areaincreases so does the discharge. The river is receiving additionalwater from the tributaries that are entering it at regular intervalswithin the Glendun valley: these will also cause the discharge tobe greater downstream. In the upper course very few tributarieshave contributed to the flow. Finally, the velocity of the river isalso greater as the water flowing in the river channel in the lowercourse does not have to overcome as much friction as that in theupper course, which has angular rocks and a shallow channel.

Most of the weathering of bare rock happens in mountainareas, where it is exposed. This material can then fall down thesteep valley sides into the upper course of the river. It is still veryangular, as the results show. As it moves downstream it hits thesides of the river bed, and also other rocks that make up the load.This knocks the sharp edges off the material, smoothing its sidesand making it rounded. The load of the river, therefore, isnoticeably more angular in the upper course, but becomesrounded in the lower course – even on a relatively short riversuch as the Glendun.

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1 Draw scattergraphs (use a suitablespreadsheet package) to show therelationship between distance from thesource of the Glendun River and:a Width (m).b Depth (m).c Discharge (cumecs).d Long axis of load (cm).

2 Quoting actual figures, describe the results.3 Do you observe any trends in the results?

How can you explain these results?4 What are the advantages of using

scattergraphs to show these results as

opposed to other types of graphs such asline graph, bar graph, pie chart, etc.?

5 What do the results tell you about theGlendun River?

6 How accurate do you think these resultsmight be? What factors might contribute totheir degree of accuracy?

7 Why do you think systematic sampling wasused in this little investigation?

8 What other types of sampling might havebeen used?

9 What would be the effect of having fewerrecording sites along the Glendun River?

Get Act ive


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6 � Figure 4 The Glendun River, Co. Antrim (scale 1:50,000). Note: (1) shows the end of the upper course of the river and (2) shows the end of the middle course

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7� Figure 5 Measurements being taken on the Glendun River

1 What evidence can you find on theOrdnance Survey (OS) map to support theview that tourists visit this area? State yourevidence from the map, draw the relevantOS map symbols and give the six-figuregrid references.

2 Calculate the distance the river covers inits middle course. Give your answer inkilometres. (Tip: be sure to check out thescale of this map. How many centimetreson the map represent a kilometre on theground?)

3 Look carefully along the course of theGlendun River and you will see the word‘Ford’. Give the six-figure grid reference forone of these fords.

4 What is a ‘ford’? Who might use these‘fords’ and for what reason?

5 In the upper course of the Glendun Riverthere is a waterfall. Give its four-figure gridreference.

6 How would you describe the valley sides ofthe Glendun in grid square 1830? What isthe evidence from the OS map to supportyour opinion?

7 Give at least four pieces of evidence fromthe map (name and grid reference) tosupport the view that settlement datesback a very long time in this area.

8 Why would much of the land in this areabe of limited use to farmers? How couldfarmers make best use of the land?

9 How would you describe SlieveanorraForest?

10 How would you describe the coastlinesouth of Cushendun?

Get Act ive

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Tom parks his car in a car parkwhere he can see a church with atower

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Peter buys a house in the villageclose to the school

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Ciara rides her horse across fieldsand over a stream

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Mary takes her children to theircaravan overlooking the sea

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Jonathan is taking photos toillustrate a book on the history ofthe Glens

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Paul is at his work as a caretakerat a National Trust property

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Alice has brought her Americancousins to watch the local hurlingteam play a game

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Driving along the Glendun theO’Neill family stop to have apicnic close to a forest

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At the end of the public walkwayAlan stops to make a call from apublic phone box

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From the top of this hill Julie cansee a telecommunications mast tothe north-east

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Billy books into a youth hostel

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Amy spots an information signalong the road directing her to anold castle nearby

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Living Map Exercise: Life in the GlensPart 1 a The location of each of the people described

in the table below can be found on the mapon pages 6–7. Work in pairs and use thedetails written about them to decide whereyou think they are. There may be more thanone possibility for some of them. Thinkcarefully about why you have chosen eachlocation. For each one, give a grid reference,and be prepared to explain your choices tothe rest of the class.

b Now imagine two more characters that youcould ask the rest of the class about. Thinkwhat clues you could give about what theyare doing and where. Make sure you knowwhere you think they would be found andwhy.

c Working in small groups, agree where youwould site one of the following: • café• bird-watching lookout• shopping centre.

1 Give your location (quoting grid square).2 State your reasons.3 Note the clues or evidence from the

map.

Part 2: Can you help?Frank and Sharon have brought their children,Jack aged 7 and Amy aged 11, to theircaravan in Cushendun on holiday. Working insmall groups, plan two days out for the family;one for a rainy day, and one for a sunny day.

Part 3: Where would you site …?a Wind Farms International PLC want to locate

a wind farm in the Glens of Antrim and havesent you to choose the best location. Thinkcarefully about all the reasons why this areawould be suitable for a wind farm. Workingin groups, agree the best location and justifyyour choice.

b As a whole class decide which groupproposal would be the best site.

Extension Activity


● Processes carried out by a river: erosion,transportation and deposition

ErosionWhen rivers have a large bed load made up of coarse materialsthese scrape or rub against the channel bed, eventually loweringthe level of the bed, creating steep valley sides. This is vertical(downwards) erosion.

In sections of the river channel where the river is flowingespecially fast, the water itself has enough energy to wash awaythe bank of the river, leading to undercutting and collapse. Asthis is a sideways motion, it is called lateral erosion.

Abrasion is the grinding of rock fragments carried by the riveragainst the bed and banks of the river. This action causes thechannel to widen and deepen. This grinding is most powerful inflood time when large fragments of rock are carried along in theriver bed.

Solution is the process by which river water reacts chemicallywith soluble minerals in the rocks and dissolves them.

Attrition is the collision of rock fragments in the water againstone another. The rock particles are broken into smaller pieces andbecome smoother the longer the process continues.

Hydraulic action is a form of mechanical weathering caused bythe force of moving water. It can undermine the river banks onthe outside of a meander, or force air into cracks within exposedrock in waterfalls.

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1 Use the OS map extract in Figure 4 on pages 6–7 to drawyour own annotated sketch map to show the course of theGlendun River. Your map should show:a the course of the Glendun Riverb the Glendun valleyc major tributariesd the upper, middle and lower courses of the rivere a V-shaped valleyf wide floodplaing land over 300 m above sea levelh Crocknamoyle, Crocknacreeva, Gruig Top and Wee

Slievenaneei Slieveanorra Forestj roadsk Knocknacarry and Cushendunl a waterfallm at least one ford.

2 Devise a suitable key for your sketch map.3 Give your sketch map an appropriate title.

Get Act ive


TransportationAll rivers contain minerals and solid material: this is known asthe load of the river. Weathered material falling into the riverfrom the valley sides forms 90% of the load. The remaining 10%is the result of erosion caused by the river on its own banks andbed.

Rivers move their load in four ways:

1 Traction – the rolling of large rocks along the river bed. This requires a lot of energy, and the largest bed load will only be moved like this in times ofsevere flood.

2 Saltation – the bouncing of medium-sizedload along the river bed.

3 Suspension – the smallest load, like finesand and clay, is held up continually withinthe river water. This makes the water appearopaque. Some rivers carry huge quantities ofsuspended material, for example the YellowRiver in China has enough sedimentsuspended in its flow at any one time to burythe city of London a metre deep.

4 Solution – soluble minerals dissolve in thewater and are carried in solution. This mayalso colour the water, for example water inthe rivers of the Mournes often appearsyellow/brown as it is stained from ironcoming off the surrounding peat bog.

DepositionWhen the velocity of the river is reduced, itsenergy falls, and it can no longer erode ortransport material instead, the load is dropped,starting with the largest, and therefore heaviest,particles. This process is called deposition.

Conditions when deposition is likely:

It is the combination of erosion, transportationand deposition that creates the general landformsseen along a river channel.

Depositionlikely if

River enters a lakeor the sea, slowing

its flow

The river floods on toits floodplain, whereit flows very slowly

There is an area ofshallow water, slowing

the river flow

The load is increasedsuddenly, e.g. after a

landslide

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� Figure 6 Methods that a river uses to move its load

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1 Traction

Saltation

Suspension

Solution

1 With the aid of annotated diagrams, nameand describe four methods that rivers use tomove their load. Check out:www.geography.ndo.co.uk/animations.htmandhttp://cgz.e2bn.net/e2bn/leas/c99/schools/cgz/accounts/staff/rchambers/GeoBytes%20GCSE%20Blog%20Resources/Animations/rivererosion_njenkins.swf.

2 Explain why rivers move more load in thewinter time than the summer time.

3 Using Figure 4, draw a cross-section of theriver in its upper course in grid square 1625and in its lower course in grid square 2332.Use these to help you describe and explainwhether the river is eroding vertically orlaterally at these points.

Get Act ive


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WaterfallsWaterfalls are generally foundin the upper course of a river,near its source area, where thelandscape is still quitemountainous. They formwhere a layer of hard rock lieson top of a layer of softerrock. As the river passes overthe soft rock, it is able toerode it at a faster rate thanthe harder rock, so a step inthe river’s bed develops. Theforce of hydraulic action andabrasion deepens this stepuntil a waterfall is formed.Eventually erosion makes adeep pool under the waterfallcalled a plunge pool and the hard rock willbegin to hang over this pool. When it becomestoo unstable, the hard rock overhang collapsesand the waterfall retreats backwards, leaving agorge.

One of the most famous waterfalls is Niagara;here hard limestone lies over softer shale.

� Figure 10 Plan and cross-section of a meander

Gentleslip-off slope

BInside of the bend

AOutside ofthe bend

Fast water hitsbed and bankthis side of the meander, eroding itfurther back and making channel deeper.

Fast waterSlow water

River cliff beingundercut by erosion. It will eventually collapseinto the river.

A

Plan view of meander

B

Cross-section of meander from A B

Deposition occurson the inside of

the meander

� Figure 8 Formation of a waterfall (cross-section)

4 Waterfall retreats upstream

2 Overhang collapses

Hard rock

3 Plunge pool develops

Soft rock

1 Undercutting

5 Steep, gorge-like valleys

� Figure 9 Niagara Falls

● Formation of fluvial features

V-shaped valley

RapidsWaterfalls

MeandersSmall floodplainPools and riffles

Large meandersWide floodplainBraided channel

Ox-bow lake

Levees

Upper course

Middle course

Lower course

Delta orestuary

� Figure 7 Landscape features in a drainage basin


MeandersMeanders are bends thatdevelop in a river channel asthe gradient (slope) of the riverevens out. They arecontinuously changing featuresthat are the result of differencesin the velocity of the riveracross its channel. Where waterflows fastest in the channel itspirals downwards, causingvertical erosion, deepening theriver channel and creating ariver cliff on the bank.Opposite this, water flows veryslowly and does not haveenough energy to erode. Itcannot even hold up the load itis carrying, so it drops(deposits) the heaviest materialfirst, then the next largest andso on, until only the smallestclay particles may be left insuspension. This leads to a lop-sided cross-section througha meander – see Figure 10.

In the middle and lowercourses of a river, meanders areconstantly being formed andreformed. The bends can getbigger and sometimes they caneven be cut off altogether, andan ox-bow lake is formed. Avery good example of a riverthat has clear ox-bow lakes andmeanders is the MississippiRiver in the USA. This can beseen at http://photojournal.jpl.nasa.gov/catalog/PIA01311 andis shown in Figure 11.

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12 � Figure 11 The Mississippi River: a good example of a river with ox-bow lakesand meanders


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FloodplainAs the river meanders back and forth it flattensthe land around it creating a floodplain eitherside of the river in its valley. The floodplain iscovered in sediments that have been depositedby the river in times of flood. This material iscalled alluvium, and is very fertile, which iswhy river valleys make good places to growcrops. Floodplains can be easily recognised onmaps. Look out for the features shown inFigure 12 on OS maps.

When the river does overflow its banks, itquickly loses energy and so must deposit muchof its load on to the floodplain. As the largestload is deposited first it quickly builds up toform natural embankments called levees.During low flow, the river may also depositmaterial on its bed, if the velocity becomes veryslow as the amount of water in the river falls.The river might even dry up altogether. If loadis deposited on to the river bed, and notwashed away later in the season, the river bedcan be raised and in some cases the river mayend up flowing above the level of thefloodplain.

Levees can be artificially strengthened andraised to protect the floodplain from flooding.

� Figure 12 Features of a floodplain

Because the floodplain is obviously likely to flood after heavy rain, the chief land use is meadow land; farmsare usually sited above the floodplainat the sides of the valley.

Regular meandersevenly spacedalong the valley

River cliff – notice the bunchingof the contours

Ox-bow lakeor mortlake – formedwhen the river cut through the neckof an old meanderleaving themortlake behind

Roads and railways often criss-cross thevalley to avoid land likely to flood, they are often built on embankments; bridgesoften built where the valley narrows

Straight sides to valley – onceshaped by the river – steepbluffs often remain – theywere former river cliffs

Meander loop

Floodplain – the flat floorof the valley submergedin the past when theriver level rose too high:nowadays river engineerstry to prevent this happening – when it doesa thin layer ofsilt or mud is depositedand it is these layersover hundreds of yearswhich have createdthe flat floodplain

70 50 50 70 90

� Figure 13 Levees

River channel

FloodplainLevee

Coarser material deposited first, close to river

River bed raised by deposition, at times of low flow(called aggraded bed)

Finer material carried furtherfrom river and deposited

Alluvium

Bluff

Layers built up throughrepeated flooding

Work in groups of three. 1 Individually, make notes to describe and

explain the formation of one of the followingfluvial features:• waterfall• meander• floodplain.

2 Give feedback on what you have learned toyour two group members.

3 Listen to their descriptions and explanationsof their fluvial features.

4 Make your own notes based on what youlearn from the other members of yourgroup. Check out the following website toview helpful animations of the processes atwork: http://highered.mcgraw-hill.com/sites/0072402466/student_view0/chapter10/animations_and_movies.html.

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● weblinks

Review your learning on rivers:

www.sciencecourseware.org/VirtualRiver/Files/page01a.html – Try out the interactive quiz.

www.georesources.co.uk/darentintro.htm – Go on a virtual fieldtrip.

http://cgz.e2bn.net/e2bn/leas/c99/schools/cgz/accounts/staff/rchambers/GeoBytes/GeoGames/geogames.htm – Try out thequizzes and games on rivers.

www.bbc.co.uk/schools/gcsebitesize/geography/riverswater/ – For the key things youneed to know about rivers and test questions.


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14� Figure 15 Station 1 on the Glendun River

Using photographs If you are investigating rivers in your projectwork try using photographs to bring life intothe project, but it is important to use themappropriately.

When using photographs:

● Only photograph what is relevant to theproject – give it a full title.

● Focus in on the important feature orbuilding you want. Annotate thephotograph in the final project.

● Include an object such as a metre rule togive an idea of scale.

Remember to keep a record of what eachphotograph shows. In this case it was Station 1 on the Glendun River. Fieldsketches are another method of illustratingproject work. Here you draw a simplifiedpicture of the geographical feature or area you are studying. Each field sketch shouldthen be given an appropriate title and be fully labelled (see Figure 14).

� Figure 14 Drawing a field sketch of Station 1 of theGlendun River

First stage:

Draw a frame the size you want your field sketch to be, then add the main lines,separating different land uses, water from land, orimportant buildings

Second stage:

Add colour to clarifyfeatures

Third stage:

Add annotation

Steep sides of V-shaped valley

Narrow riverchannel

Grasses onvalley sides

Large bedload

Rapids with'white water'


● Land uses near riversHumans have found many uses for both rivers andthe land next to them. In more economicallydeveloped countries (MEDCs), cattle may begrazed on damp floodplains, or factories, whichneed water for cooling, might locate next to ariver. Housing has also been built on floodplains.In less economically developed countries(LEDCs), floodplains make good natural paddyfields for growing rice and provide fertile land formany other crops.

In many places, settlements have grown upnext to the mouth of rivers to take advantage oftrading opportunities.

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� Figure 16 A boy working in a paddy field in Indonesia

What are the reasons for developing land ona floodplain? In groups, read and discuss each of thestatements below that outline reasons fordeveloping land and living next to a river thatcould, at some time in the future, flood. Someof the statements are true but others are false.One or two may be partly true and partly false.Can you decide which ones are which?

Sort the statements into the three categories:

• true • false • partly true/partly false.

1 Most lowland river floodplains are flat. 2 Despite flooding dangers, riverside building

plots are very expensive. Only very largeexecutive style housing over £300,000 cantherefore be built, helping to pay for the highcost of land.

3 Heavy industrial developments in the 1990swere built next to rivers to allow easy importof bulk raw materials.

4 Housing estates can be built next to rivers,provided adequate flood protectionschemes are constructed beforehand.

5 Factory developments have been built onriver floodplains because there is plenty ofroom to expand if factory extensions areneeded in the future.

6 Only expensive housing is built next torivers, as buyers with money like beautifulscenery and country views.

7 New housing developments are often builtnext to rivers so that river sand and gravel

can be used in construction. It reducestransport costs.

8 Development on floodplains is far easierbecause the land is flat, and theconstruction of buildings is so much easier.

9 New housing development next to rivers isfar too risky, and insurance companies willnot insure against flood damage.

10 The only use for floodplain land, next to ariver, is for the grazing of livestock (cowsand sheep). Animals can be moved if thereis a danger of flooding. The land is thereforevery cheap to buy for alternative propertydevelopment.

11 Houses in Britain are often built next torivers to supply a reliable and cheap supplyof drinking water.

12 The demand for new housing is increasing,and we are running out of flat land todevelop. The only cheap option is to buildon floodplains, and hope there are fewserious floods.

13 Houses can no longer be built on flood plainsites, liable to flooding, due to newgovernment building regulations.

14 Local authorities and building companies willbuild on any available land, even if it is liableto flooding, if they can make large amountsof money from a deal.

15 New housing and factory developments,with linking roads, are still being built next torivers that may flood, because it gives achoice of routes reducing traffic congestionin the rush hour.

Source: Based on an idea from www.taw.org.uk.

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Coastal processes and featuresWe gained our 10,000-mile long coastline following the end ofthe Ice Age when the British Isles obtained its familiar shape aslowland areas filled with melt water to form the Irish Sea, NorthSea and English Channel. The Irish Sea was filled first, cuttingIreland off from mainland Europe, which is why Ireland only has20 native species of mammals.

The sound of the waves crashing on to a shore evokes a strongreaction within a person’s spirit. We are an island, so a stretch ofcoastline is never more than a few hours’ drive away.

● WavesWaves themselves are the main force of coastal change. Wavesare caused by wind blowing over a stretch of open water, calledthe fetch. The greater the fetch, the larger the wave. This is why the Atlantic coastline of Northern Ireland has better surf conditions than the more sheltered eastern coastlinebordering the Irish Sea. Although fetch is important, wind speedcan greatly affect wave height. The stronger the wind, the biggerthe waves.

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� Figure 17 Coastal erosion

4 From this point the energyand the water's rotation causethe wave to move onwards

Wind5 Water surges up the beach: the swash

6 The water then moves back down the beach: called the backwash

1 In the open sea, the wind pulls at the surface of the water causing the wave to move

2 Inside the wave, the water rotates and returns to its starting point

3 When a wave reaches the shallows at the coast it distorts until it 'breaks'

As a wave approaches the coast, its lower section is slowedmore than the upper sections due to friction from the beach orseabed. The upper section of the wave reaches a crest thentopples over (breaks) and either hits a cliff face or surges up abeach as the swash of a wave. As the wave retreats back it createsa backwash. Waves with a strong swash and weak backwash arethe constructive waves and they push material up a beach. Waveswith a strong backwash pull material out to sea, and are thereforedestructive waves that erode coasts.


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� Figure 18 Destructive waves

Waves are closeto each other

A steep wave front

The breaking wave collapses

Steep sloping beach

The backwash pulls sandand pebbles into the sea

� Figure 19 Constructive waves

Wave crests are far apart

A gently sloping wave front

The braking wavespills forward

Gently sloping beach

Strong swash pushes sandand pebbles up the beach

Reinforce your knowledge of waves. 1 Check out the diagrams and short video clip at:

www.geography.learnontheinternet.co.uk/topics/waves.html.2 Listen to a podcast on ‘Energy at the coast – waves and

wave formation’ (made by St Ivo’s School GeographyDepartment):http://cgz.e2bn.net/e2bn/leas/c99/schools/cgz/accounts/staff/rchambers/GeoBytes/GCSE%20Revision/Podcasts/Coasts%20Podcast/Coasts_part1.mp3.

3 With the aid of diagrams explain the difference betweenconstructive and destructive waves.

Get Act ive

Characteristics of destructive waves● They have a strong backwash compared to their swash.● They are high in relation to their length.● They are frequent waves (break at a rate of close to 15 per

minute).

Characteristics of constructive waves● They have a weak backwash compared to their swash.● They are long in relation to their height.● They are gentle (break at a rate of 6–9 waves per minute).

Coasts are amazing places that seldom remain the same shape forlong. This constant changing makes them one of our mostdynamic landscapes.


● Coastal processesAs with rivers, the sea also erodes, transportsand deposits material. Unlike a river, however,the sea has a much greater force and can movematerial all around the globe! Coconuts fromthe Caribbean may be found on the beaches ofsouth-west Ireland and Cornwall.

ErosionWhen we think of coastal erosion it is useful tothink of the acronym C-A-S-H.

● Corrasion – when a wave hits the coast, itthrows sand and pebbles against the cliff face.These knock off small parts of the cliff andcause undercutting. Another word for this isabrasion.

● Attrition – particles being transported by thesea hit against one another, reducing their sizeand making them more rounded, just like inrivers.

● Solution – seawater can dissolve away therocks from the seabed or cliffs. This process isespecially effective on limestone coasts, andcan create spectacular caves. It is also knownas corrosion.

● Hydraulic action – the power of the sea canphysically wash away soft rocks like boulder

clay. Under storm conditions with strongwaves, hundreds of tonnes of seawater can behitting the coast. Also air can be trapped insmall cracks within a cliff when a wave breaksagainst it. This compressed air can widen thecracks, eventually leading to a large section ofcliff breaking away from the main cliff face.

TransportationJust like rivers, the sea also transports material.The processes are the same as fluvial transport:that is saltation, suspension, solution andtraction. On a beach, waves can move materialin one direction more than another; this iscalled long-shore drift. This process is discussedin more detail during the explanation of spitformation on page 22.

DepositionWhen the load of the seas and oceans builds upon the coastline it forms beaches, spits and sand dunes. This material is added byconstructive waves. Deposition occurs during periods of light winds. This means that the summer is the most common period forthis process to occur in the UK. Constructivewaves are most effective in sheltered coastallocations such as bays.

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18� Figure 20 A destructive wave hits Cornwall in March 2008. The hydraulic power of this wave is huge


● Coastal landforms anderosion

Cliffs and wave cut platformsA cliff is a vertical rock face along the coast.The shape of the cliff is determined by thenature of the geology. The type of rock the cliffis made from determines how resistant it is toerosion, and the way the layers (strata) of therock are angled can determine the shape of thecliff. Where the rock is hard, dramatic tall cliffscan form, but with weaker rocks, like theboulder clays of the Holderness coast in England,then erosion is faster, but the cliffs are lessdramatic.

A wave cut platform is the narrow flat areaoften seen at the base of a cliff. It is caused byerosion. First a notch is formed at the base of thecliff due to corrosion and hydraulic action,serving as a point of weakness. The upper cliffface is undercut and eventually collapses. Thishappens again and again, until a new landform,called a wave cut platform is created at the baseof the cliff. It is only fully exposed at low tide.

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� Figure 21 A schematic showing how coastal erosionoccurs

Loosened sections ofrock easily fall away

Cliff sloping at sameangle as the strata

Steeper cliffs are foundwhere strata are horizontal or slope inwards

Strata sloping towards sea

inland

Strata slopinginland

Horizontal strata

� Figure 23 Formation of cliff and wave cut platforms

New rock exposed

Area attacked by wavesbetween high and lowwater marks

Rock face overhangs

Wave cut notch showing undercutting by the waves

High water

Low water

1

High water

Low water

2

High water

Low water

3

Cliff retreats inland

Overhanging rockhas collapsed

Wave cut platformis formed

� Figure 22 Wave cut notch visible on the Ballintoy coast

Explain the formation of a cliff and wave cutplatform.

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Wave cutnotch


Caves, arches andstacksA wave cut notch may enlargeinto a cave. Following furthererosion, the cave erodesthrough the headland to forman arch. The waves andweathering from the elementsundermine the upper portion ofthe arch until it cannot hold itsown weight up, and collapses toleave a stack.

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� Figure 24 Erosion of a headland

1 Weak areas are pounded by waves and open to make a cave

2 Cave widens and deepens and becomes an arch, e.g. Durdle Door, Dorset

3 The waves erode the arch roof until it collapses forming a stack

4 Headland retreats. The stack is eroded until it becomes a stump

Headlandretreating

1 As a class, watch the video at this link sothat you are able to identify the coastallandforms described above from theirdistinctive features:http://geobytesgcse.blogspot.com/2007/08/coastal-erosion-landforms-features-and.html.

2 In small groups read and discuss the section headed ‘Coastal Erosion Landforms – Features and Formation’ on thewebsite.

3 Working individually, your task is to prepare a short presentation using Photo Story 3 to explain the formation of one of the

following coastal landforms: cliff, wave cut platform, cave, arch, stack, stump.

• Start by carrying out an internet search tofind an example of your feature.

• Continue your internet search to find atleast two good photographs of yourexample.

• Import your photographs into Photo Story 3.

• Add your own narration, saying what yourfeature is, its name, its location, what it islike and how it was formed.

• Watch all the presentations.

Get Act ive

� Figure 25 Old Harry Rocks, Studland, Dorset: an example of an eroded headland

Wave cutplatform

Collapsedarch

Stack

Cave


● Landforms of coastal deposition

BeachesBeaches are the most familiar coastal landform created bydeposition. They are formed in the intertidal area between highand low tide where constructive waves push material like sand,shingle and pebbles on to the coast. Over time this material canbuild up and be blown inshore by wind to create a beach. Thesupply of beach material depends on erosional rates further up thecoast. On sandy beaches, the backwash of the waves still removesmaterial, forming a gently sloping beach. On shingle beaches theenergy of a wave is reduced because the large particle size allowspercolation, so the backwash is not very powerful, and a steepbeach is created.

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� Figure 26 A sandy beach – Whitepark Bay, Co. Antrim

� Figure 27 A shingle beach – Bawdsey Beach, Suffolk

1 Why are shingle beachessteeper than sandybeaches?

2 What type of waves formbeaches?

Get Act ive


Spits These are depositional features made of sandthat look like beaches and extend out from themainland into the sea. They form if thefollowing conditions are met:

● There is a constant supply of sand or othermaterial from erosion further up the coast.

● Long-shore drift operates most of the time.● The coastline has a sudden change in

direction to leave a sheltered bay area.● The sea is quite shallow.

The end of a spit may be curved if it grows farenough out into the sea to meet more powerfulwaves or waves from a different direction. Newland can be established behind a spit on thecoastal side where mud accumulates to createsalt marshes which will eventually becomeuseable land.

One famous example of a spit is Spurn Headin northern England. Erosion of boulder clayfrom the Flamborough Head region and asoutherly long-shore drift direction has createdthis landform. It is not fully permanent as mapsof the area show that it has been destroyed bystorms four times in the last six hundred years.The most recent was in 1996. Each time it hasslowly been rebuilt by long-shore drift.

A local example is in Dundrum Bay, wheresand and shingle from Newcastle have built upa small spit. New coastal defences in Newcastleand sea level rises forecast for the region havejeopardised its future survival.

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� Figure 28 Google Earth image of Spurn Head

� Figure 29 Map of Spurn Head

Spurn Head

NorthSea

Grimsby

Hull

R. HumberN

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1 Carry out an image search on the internet to find aphotograph of Spurn Head. Print out a copy of what youconsider to be the best image of this coastal feature. Use themap extract and the aerial photograph to draw an annotatedsketch map showing the location of the spit at Spurn Head.

2 Describe what the spit looks like today. 3 Describe the process that led to the formation of the spit at

Spurn Head. 4 What is the direction of the long-shore drift here?5 Use the map to calculate the approximate length of the spit.6 Will this spit keep the shape it has today? How might it

change in the future?7 What processes might change Spurn Head in the future?

Get Act ive


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● weblinks

www.georesources.co.uk/recintro.htm – Goon a virtual tour about coastal management insouth-east England.

www.fife-education.org.uk/inspiration/coasts/coastal_processes_menu.htm – For activeboard users there are interactive quizzes.

http://geobytesgcse.blogspot.com/2007/08/coastal-processes-erosion-transport-and.html– For revision notes

www.wellingtoncollege.org/page.aspx?id=6740 – For PowerPoints and usefulinformation.

● Coastal land use Coasts are used for many purposes. In the past,cliffs made excellent defence sites for castles orlarger settlements. Today they see many tourismuses, such as car parks, caravan parks, nature

reserves, golf courses and walks. Some spits andcoastal areas are used for agriculture and ofcourse fishing and trade. Many of these uses canbe seen in Figure 30.

� Figure 30 A defensive site on the coast: Dunluce Castle in Co. Antrim

In pairs, create a colourful and informativeposter to illustrate different coastal land uses(e.g. residential, industry, business, leisure,sport, etc.). Think in terms of past, presentand the future; things you like or dislike; thingsthat threaten or preserve the coastline; thingsfor people of different ages:

• Carry out an image search on the internet.• Save the photographs that you both like.• Print out the photos.• Arrange on a large flipchart sheet.• Add appropriate labels.• Display finished poster in the classroom.

Complete a Two Stars and a Wish activity onthe posters by writing down on sticky labelstwo things that you like (Stars) and one thingthat you think would enhance/improve theposters (Wishes). Individually, describe coastalland use in Northern Ireland.

Get Act ive


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� Figure 31 Murlough National Nature Reserve. Scale 1: 25,000

Direction oflong-shoredrift

24


Part ATake a virtual visit of Murlough Bay, Co. Down (www.virtualvisit-northernireland.com/gallery.aspx?dataid=49754&id=869&title=Nature%20and%20Wildlife) and thenanswer the following questions:

1 Describe the sand dunes at Murlough Bay Nature Reserve.What words would you use to describe the terrain, thevegetation cover? Why has the boardwalk been laid on thedune? Is there any evidence of human activity on the dune?How does human activity threaten a fragile ecosystem like acoastal sand dune?

2 Describe the beach at Murlough Bay Nature Reserve. Whatdoes it look like? What is it made up of? Is it narrow or wide?Is the slope of the beach gentle or steep? Is there anyevidence of human activity on the beach?

3 Are there any questions you wish to ask about this place?

Part BLook carefully at Figure 31 showing Murlough Bay NatureReserve and the spit and answer the following questions:

1 What is the scale of this OS map?2 How wide is the spit at its widest point?3 Who owns the land on the spit? What is the evidence for

your answer?4 What is the name of the large home on the spit?5 Which sport could be played in grid square 3932? What is

the evidence for your answer?6 Along which famous pathway can one walk on the spit?7 Which river flows into Dundrum Bay in grid square 3934?8 What is the direction of the long-shore drift along this part of

the County Down coastline?9 Give the six-figure grid reference of the chambered grave.

10 What evidence is there on the map to suggest that visitorsmay come to the area?

11 Giving evidence from the OS map extract, name threesporting activities young people could engage in if visitingthis area.

12 Use NI maps (accessible in the links area of Learning NI) tolook at recent aerial photographs of Murlough Bay. Whatdoes it show?

Get Act ive

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Sustainable management of riversRivers are an important resource to people, so any changes madeto them need to be sustainable. Future generations will need theserivers just as much as we do today.

● Causes of floodingFloods are temporary excesses of water that cover areas that areusually dry.

Physical causes

Human causes

Less root support for soil

Less water used by plantsDeforestation

Urbanisation

Narrowing a river channel, e.g. by building a bridge

Big raindrops no longer broken up by leaves

More flooding

More tarmac and concretecreates impermeablesurfaces

River has a reduced capacity to hold water

Provides short-term protection, but …

More likely to flood

Severe flash flood

If breached by a higher than planned for flood level

More surface run-off

Building of levees(embankments)

Heavy rainfall – especially thunderstorms

Excessive surface run-off Flash flood

Prolonged rainfall as in a monsoon climate

Saturates the ground Slow, long flood

Melting of a glacier or snow

Creates high river discharge in spring

Rivers overflow

Underlying rock is impermeable or clay soil.

Reduces infiltration into the ground – meaning precipitation is more likely to be taken to the river as surface run-off

High risk area for regular flooding.

Ground is frozen

Uses of rivers● A source of water – irrigation and water supply.● A source of power – hydroelectricity or water mills.● A waste outlet – used as a drain taking effluent out to sea.● A routeway – roads and rail links follow valleys, river traffic

and shipping.● A source of food – fish makes up the main source of protein in

many LEDCs.

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case study

The causes of flood in the British Isles: the River Derwent in 1999In March 1999 people living near the River Derwent, Yorkshire,experienced its worst flooding in 70 years. Places nearby wereflooded up to 1.5 m deep and two main roads had to be closed.

Some causes of the flood

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� Figure 32 Map showing the drainage basin of the River Derwent

N

0 10

km

Below 100 m

NorthSea

100–300 m

Above 300 m

Direction ofriver flowRiver Derwentcatchmentboundary

Barmby-on-the-Marsh

Pocklington

Stamford Bridge

Norton

Malton

Pickering

Ness

Helmsley

North Yorks Moors

Scarborough

Filey

R. D

erw

ent

Spittle Beck

R. R

ye R. Derwent

R. D

ove

Pick

ering Be

ck

� Figure 33 Stamford Bridge underwater following the Derwent flood in1999

Human

● Peat removal – the extraction of peatin the source area lowered the soilstorage capacity there, as peat actslike a sponge.

● New building – areas of thefloodplain were being urbanised,such as the new estate built atMalton. This reduces infiltration butincreases surface run-off.

Physical

● Heavy rainfall – between 28 February and 11 March over250 mm of rain fell on the North Yorkmoors.

● Lack of infiltration – this rainfall fell onto ground that was almost saturatedfrom previous rainfall events.

● Time of year – there was snow meltadding to the discharge from theNorth York moor source region.

Find out about more recent flood events in the UK. You canget some idea of the extent of one flood by looking at theaerial photographs at: www.webbaviation.co.uk/gallery/v/greatfloods/.

Your task is to produce a PowerPoint presentation on thisevent. It should outline the factors that contributed to theseverity of the flooding (both physical and human), describehow the flood affected people and the environment (naturaland built) and include a location map, photographs and anyrelevant diagrams. Your presentation should have a maximumof 10 slides. You could add your own narration ormusic soundtrack.

Share the presentations.

Get Act ive


● Impacts of flooding

On people

On the environment

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Positive impacts Negative impacts

• Replenishes drinking watersupplies, especially wells.

• Provides sediment (other termsare silt or alluvium) that naturallyfertilises the soils of the floodplain.

• Countries such as Bangladeshand Egypt rely on floods.

• Spreads waterborne diseases.

• People and animals can bemade homeless or even drown.

• Buildings and infrastructure(roads and railways) can bedamaged or destroyed.

• Crops grown on fertilefloodplains can be washedaway in a flash flood.

Positive impacts Negative impacts

• Fish benefit as they can breed in the standing floodwater.

• In dry areas, floods bring relieffrom drought, providing drinkingwater for wild animals.

• Flooding can wash chemicalsor sewage into the local riversand so pollute them.

• Wild animals may drown or losetheir habitat during a flood.

1 Working in groups of three or four, you aregoing to think about flooding in terms ofcause and effect by completing an AnalysisTree activity. Your group needs a large sheetof flipchart paper and some colouredmarkers.

2 On your page draw a tree with branches androots like the one below.

3 On your tree the roots represent the causesof flooding and the branches represent theeffects of flooding.

4 Talk about the causes of flooding (physicaland human) and add the points that youagree on to the roots of the tree.

5 Talk about the effects of flooding (positive andnegative) and add the points that you agreeon to the branches of the tree.

6 Select a reporter to give feedback to the restof the class.

7 Use the analysis trees from the differentgroups to make revision notes on the topic.

8 Individually, reflect on what you liked/dislikedabout this activity and how useful you foundit. Did using the tree help you to clarify yourthinking?

Get Act ive


● River management strategiesRiver management schemes aim to control rivers and reduce therisk of unwanted flooding. Planners can respond to the floodhazard by changing the river through engineering. They mightimplement hard or soft flood control measures.

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You have learned how river managementschemes aim to control rivers and reduce therisk of flooding. In the case of the MississippiRiver, USA, numerous hard and soft floodcontrol measures had been implemented byplanners to protect the inhabitants of citiessuch as New Orleans.

Part AWorking in groups, consider the followingquestions. You will need to use a searchengine such as Google (www.google.co.uk) orBBC News (www.bbc.co.uk/news) on theinternet to find appropriate information onHurricane Katrina:

1 Why did Hurricane Katrina have such adevastating effect on New Orleans?

2 In what ways were the flood controlmeasures that were already in place beforethis particular hurricane ineffective?

3 Copy a photograph from the internet thatshows the extent of the flooding in NewOrleans. If possible, highlight (by adding

labels to the photo) any of the hard or softflood control measures that had been put inplace but which had failed in their intendedpurpose.

4 In the future what hard and soft flood controlmeasures might be put in place by the cityauthorities to better protect the people thatlive there?

5 Should the city of New Orleans be rebuilt toits former glory? What are the argumentsfor and against such a proposal?

6 Should new housing developments in theUK and Ireland be allowed on floodplainswhere there is a history of flooding?

7 Can planners in the UK and Ireland learnanything from the New Orleans experience?

Part BAppoint a representative from each group togive feedback to the rest of the class.

Part CMake notes on what has been learned in thiscase study.

Get Act ive Extension

Soft engineering flood controlsSoft engineering flood controls are generallysympathetic to the natural landscape, so tendnot to damage the river for future generations,making them more sustainable than hard floodcontrol measures. They may involve:

● Planting trees (afforestation) in the uppercourse of the river.

● Land use zoning – when areas most likely tobe flooded are protected from urbandevelopment.

● Washlands – these are parts of the riverfloodplain in the lower course, into which theriver can flood temporarily. They are one kindof flood storage area.

Hard engineering flood controlsHard engineering flood controls often involvemaking large artificial structures to control theriver, breaking its natural cycle of flood andsubsidence. These measures are not sustainablein the long term. They may involve:

● Building a dam or reservoir in the uppercourse. The resulting reservoir can be used forleisure and hydroelectricity, but can floodgood farmland and displace local people anddestroy habitats.

● Changes to the river channel. By deepeningand widening the river channel, they increaseits cross-sectional area, allowing it to containmore water, meaning the discharge has to begreater to create a flood.

● Building high embankments along the sides ofthe river to contain any floodwater.


case study

BackgroundThe Mississippi River has one of the largestdrainage basins in North America – it drainswater from a third of the USA and part ofCanada. It is located in the south-east of theUSA. When it flooded in 2001 some 4400people had to move and the damage cost $13 million.

Management response to the flooding

Hard engineering1 Raised levees. Levees were raised to 15 m

and strengthened to enclose the river channelfor a stretch of 3000 km.

2 Straightening the river channel – meanderswere cut through over a stretch of 1750 km,creating a fast-flowing straight river channel.

3 Dams – the flow of the main tributaries, e.g.Ohio River, has been controlled by 100 dams.

Soft engineering1 Afforestation in upper course – trees have

been planted in areas such as the TennesseValley to intercept some of the rainfall andstabilise soil.

2 Safe flood zones – building has beenrestricted in many of the floodplain areas, andin areas like Rock Island where housing hadalready been built on the floodplain, thehousing has been bought by the county anddemolished.

Evaluation of such measuresRemember that to manage a river sustainablythe needs of the present generation must be metwithout endangering the ability of futuregenerations to meet their needs.

The Mississippi River is very important to theUSA since 18 million people rely on it for theirwater supply – so carefully co-ordinatedmanagement decisions need to be made aseach decision in one state may affect millions ofpeople’s water supply in another state.

Current hard engineering methods haveproven neither totally effective nor sustainable.

The river still floods, and indeed thedangerous flash flood nature of the 2001 floodshas been partly blamed on the artificial leveesfailing. Also, as the river silts up along the levees,river beds rise and the floodplain ends up belowthe river level, e.g. New Orleans where someareas are 4.3 m below river level.

For current and future generations, the lack ofsilt reaching the land means that fertility of thesoil is no longer being naturally completed duringthe deposition of alluvium in the floods.Eventually more and more artificial fertilisers willhave to be added to the soil.

For wildlife, the draining of wetland and lack ofsilt to maintain the delta is destroying valuablehabitats. This means that birds like the heron arebecoming endangered in that area.

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A river management scheme outside the British Isles: the Mississippi River

● weblinks

www.big-river.com/ – A good general site on the Mississippi.

http://floodsim.com/ – Try saving millions of people in a floodmanagement simulation game.

http://news.bbc.co.uk/1/hi/uk/292691.stm – Study the effects of the Derwent flood.

www.dartmouth.edu/~floods/Archives/1999sum.htm – Compare the Derwent flood to others of 1999.


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� Figure 34 Main features of the Mississippi River

Red

Arkansas

Missouri

Mississippi

1

2

3Ohio

Tennessee

B

C

A

1 New Orleans

2 Cairo

3 St Louis

A Ohio–Tennessee rise in theAppalachians which receiveheavy cyclonic rainfall betweenJanuary and May. Flood riskincreases following snow melt.

B Right-bank tributaries drain relatively dry. Mid-west rainfallmostly falls in summer whenevaporation is at its highest.

C Lower Mississippi usual and most frequent floods.

� Figure 35 An example of a hard engineering project –Fontana Dam, North Carolina, USA

1 How successful do you judge theMississippi River management scheme tohave been?

2 Working in groups, complete a PMI analysis(plus = a benefit; minus = a downside; andinteresting = an interesting point stemmingfrom the topic under discussion) on each ofthe soft and hard engineering flood controlmeasures implemented in the Mississippischeme. Record the views of the groupusing a table like this one:

You will need to create a table for each ofthe flood control measures (hard and soft)implemented on the Mississippi River.

3 List the ways the Mississippi rivermanagement scheme has had an impacton:• people• the environment.

Flood control measure: Building dams

Plus Minus Interesting

• • •

• • •

• • •

Get Act ive


Sustainable management of coasts● Human activity on coasts Figure 36 shows a hard coastal engineering strategy – a stone seawall. This makes the sea hard to reach for tourists. Figure 37 isevidence of a conflict between transport and tourism when a boatcarrying wood crashed and spilled its load over a tourist beach inSussex.

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� Figure 36 A stone sea wall in Sea Palling, Norfolk

� Figure 37 A boat spilled its load on to the beach at Worthing, Sussex


● The conflicting nature of human activity on coastsThere are four main land uses seen in coastal zones.

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ResidentialA sea view is very desirable; many peoplewant to see the sea from their house. Thismeans that there is great pressure on locallandowners and councils to develop housingor hotels in coastal locations, which may ruintheir natural landscape value forever. Thesecond problem is that demand is greaterthan supply, so coastal homes can prove to betoo expensive for some local people in localtowns to afford. Also it has led to somehomes being built in locations which arethreatened by coastal flooding and sea levelrise. This is the case on the Florida coast andin Bangladesh.

TourismAlmost everyone enjoys a beach holiday, and this can cause conflict with residential land useand industry. In Jamaica there is a three-storey height restriction law for housing and hotels, sothe skyline does not become as blighted by tall hotels as in some Spanish and American resorts.Tourism does bring money into the economy, but it can be hard to make it sustainable. This is acurrent issue for the north coast of Northern Ireland, where people are slowly eroding away thevery Giant’s Causeway which they came to see.

� Figure 38 Unsuitable housing near the coast ofBangladesh

� Figure 40 The unnatural seafront in Miami, Florida,USA

� Figure 39 Tourists on the Giant’s Causeway, slowlywearing it away


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TransportRoad and railway lines that follow coastlines cost more money to maintain and some need specialplanning to ensure they canremain open. Others aresacrificed to the sea, as on theHolderness coastline inEngland. Coastal transportalso includes ships, andnatural harbours have beenmanaged for generations toallow the safe passage of boatsfrom the open waters of seasor oceans. Today, in order toaccommodate the newestlarge ships, calledsupertankers, many ports arehaving to relocate to deeperwater or dredge to increasetheir depth. This is a pressurefrom industries who wantproducts moved faster andmore cheaply.

� Figure 41 A road now going nowhere, but disappearing at the rate of 2 m per year in Holderness, Yorkshire

IndustryAs oil supplies can beextracted from underwaterlocations, the North Seacoastline of Scotland has seendramatic changes due to oilextraction. In Aberdeenalone, 100,000 people areemployed by the oil industry.

Offshore, the mainindustrial activities are fishingand commercial shipping, andthere is also some dredging formarine sediment.

Shipbuilding and ship-breaking are alsocommonly seen on coasts.The negative impacts of thecreation of the Alang-SosiyaShip-Breaking Yard (ASSBY)in a sensitive coastal area inthe state of Gujarat, India,present many challenges andlessons for practitioners ofintegrated coastalmanagement.

� Figure 42 Alang-Sosiya ship-breaking yard in India. To investigate the Alang-Sosiya ship-breaking yard go to: http://unesdoc.unesco.org/images/0013/001375/137515e.pdf


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Spain 2008Rampant development has turned much of Spain’s

Mediterranean coast into concrete jungles. Now, the country’s

environment ministry is determined to fight back, taking on the

unchecked and frequently illegal construction that has

threatened to overwhelm Spain’s shores – causing erosion rates

of up to 1 metre per year. The environment ministry had 665

buildings demolished and more are planned. Adapted from

www.csmonitor.com/2008/0117/p13s01-woeu.html

Human activities areeroding close to

70% of the world’sbeaches at greater thannatural rates. Coastlinesin developing countriesare suffering fromserious erosionproblems due tounplanned coastalconstruction, dredging,

mining for sand,harvesting of coral reefsfor building materialand other activities.Erosion is particularlysevere along the coastsof Nigeria, SierraLeone, Liberia, Gambia,Benin and Togo in WestAfrica. Hundreds ofcoastal villages have

been moved inland asthe sea advances. In theNiger River Delta, forinstance, erosion claims400 hectares of land ayear and 40% of theinhabited delta could belost in three decades.

AFRICA 2009: 70%OF CORAL REEFSCOULD BE GONE IN 40 YEARS

� Figure 43 Headlines on coastal development

Coastal erosion


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Look at the photo below showing the seafrontin Torremolinos, a popular sunshine destinationin Spain for holidaymakers from the UK andIreland.

You could also do an internet search onTorremolinos to further your knowledge andunderstanding of the impact mass tourism hashad on this part of the Spanish coast.

1 With a partner, discuss and note thecompeting demand for land in a place likeTorremolinos.

2 What are the advantages and disadvantagesof such development in coastal areas?

3 In your opinion, do the advantages of suchdevelopment outweigh the disadvantages?Give detailed reasons.

4 What, if any, different approach could havebeen taken to the development of this coastalarea?

Get Act ive

� Figure 44 Torremolinos, Spain


● The need for coastal defencesThe protection of coasts is important as just overhalf the world’s population – around 3.2 billionpeople – live within 200 km of the sea. In allcontinents, except Africa, the majority of peoplelive near coasts.

Coastal zones include waters and shores ofcoastal lands as well as islands, salt marshes,wetlands and beaches. The use of the shorelinehas a direct and significant impact on the coastalwaters and the large numbers of people thatinhabit the areas. Geographical informationsystems (GIS) are used to understand andcontrol those areas that are likely to be affectedby or are vulnerable to rising sea levels or coastalerosion.

Global warming is making the need for coastaldefences a pressing issue for many low-lyingcoastal regions and countries. The averagepredicted rise in sea level due to the thermalexpansion of water is about 48 cm, although itcould be up to almost 90 cm by the end of thecentury. The World Bank estimates that a 1-mrise in sea level would flood half of Bangladesh’srice fields and force the migration of millions ofpeople. The European city of Amsterdam isalready mostly below sea level, and relies on seadefences to protect it from flooding. The

islanders of Tuvalu, in the Pacific Ocean, havealready made plans to abandon their homeland asit is now regularly being flooded by rising tides.

Coasts are economically important to manycountries as the main ports are the centre ofcommerce, trade and investment. The marshareas provide natural areas for waste assimilation and detoxification. The incomegenerated from fishing can be vital and tourismcan be very lucrative. As much as 60% ofMajorca’s gross national product (GNP) isgenerated by tourism, which is centred aroundthe beaches.

● Coastal managementstrategies

Coastal areas need management to:

● keep the sea out● retain cliffs and beaches.

Sea wallsThe most common way to keep the sea at bay isto build sea walls. These look like tall concretewalls built at the back of beaches. They mayhave a curved shape which is designed to deflectthe erosive energy of the wave and add extraprotection against waves topping the wall.

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37� Figure 45 The sea wall in Portrush, Co. Antrim


Retaining cliffs and beachesSea walls are expensive to build and the need forconstant maintenance means costs continue.They can be economically acceptable if they areneeded to protect many people and properties,like in Portrush.

Cliffs can be difficult to retain, but recentlygabions have been used successfully as a short-term measure to stabilise cliff bases. A gabion isa metal cage, measuring about 1 m by 1 m, thatis built on site from six metal mesh sides andthen filled with local rocks. As gabions rust andcan be damaged during severe storms, they donot provide a long-term solution to coastalmanagement. Such damage is seen in Figure 47,where the nearby gabion baskets on ChillingCliff in Hampshire have been damaged by astorm. The main advantage they have is theirlow cost.

Beaches are essential natural coastalprotection and are a main tourist attraction toany coastal area, so many resorts are keen toensure they are conserved.

When long-shore drift is displacing sand froma beach, then groynes or beach replenishmentare strategies used to ensure beach survival.

Groynes are often made of hard wood and looklike low fences stretching seawards out along abeach at intervals of about 50 m. They slowdown long-shore drift and promote thedeposition of sand, building up the beach. Thewood will eventually weather down and sogroynes have a lifespan of 20 years. Modernconstruction techniques favour rock groyneswhich have a much longer life span than woodenones. They can cause problems of public accessalong a beach and can lead to extra erosionfurther down the coast as beach material cannotmove naturally by long-shore drift.

Beach nourishment is sometimes calledbeach recharging. Sand is dredged from theseabed and added to an eroded beach, or evenbrought in as lorry loads to add extra materialalong a stretch of coastline. It is veryexpensive, costing about £1 million per mileand is not a permanent fix. Nourished beacheserode faster then natural ones because the sandis not as tightly packed. As it costs so much,the economic returns, generally throughtourism, must be great.

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Figure 46 shows a curved sea wall. Why is iteffective at keeping the sea at bay? Whywould a sea wall that is more vertical be lesseffective in keeping the sea at bay?

Get Act ive

� Figure 46 A curved sea wall in Blackpool

� Figure 47 Collapsed gabions near Aberdeen

● weblinks

www.snh.org.uk/publications/on-line/heritagemanagement/erosion/sitemap.shtml – A guide to managing coastal erosion inbeach/sand dune systems from the ScottishNatural Heritage.


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39� Figure 49 Beach nourishment: before and after photos of beach restoration efforts of the Florida coastline in 1972

� Figure 48 How groynes can change the shape of a beach

Direction of long-shore drift

Sea

Beach

Old coastline

New coastlineGroyne

Sand trapped by extra deposition

Sand area lost by erosion


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Tourism has been the major cause of coastalpressure in Newcastle, Co. Down. The openingof a rail link between Belfast and the town in1869 meant that the seaside resort was just anhour’s journey from the city. The town is set in abay, which boasts 8 km of beach that attractstourists. Boarding houses were built as close tothe sea as possible. Even today Newcastle is apopular day or weekend destination, withthousands packing the beach and main streetson bank holidays. It has been estimated that thepopulation of Newcastle rises by 15,000 in thesummer months, and it’s all down to tourism.

Evaluation of coastal defences

BackgroundNewcastle sits in Dundrum Bay, which has a 20-km long beach running between St John’sPoint and Newcastle Harbour. Waves are themost important driving force controlling the naturalcoastal system here. These waves are gentle, asthere is a limited fetch area, and approach fromthe south-east. The shallow and wide beachdissipates wave energy, meaning constructivewaves dominate, except during storm times. Thesediment which makes up the beach was washeddown from the mountains after the last Ice Age. Awave cut notch in Dundrum Village at 14 m abovethe current sea level is believed to mark themaximum height of the sea during the late glacialperiod 15,000 years ago. There have been manyattempts to control the coast at Newcastle usinghard engineering methods.

GroynesThe old urban council created concrete groynesnear the Newcastle centre section of the beach inthe 1980s, to trap and hold sand that was driftingnorth-east. Since they have now decayed, theycan no longer perform this function and mayhave contributed to sand loss at Newcastle.

The present council is carrying out a study tosee if a new set of wooden groynes couldstabilise sand on the beach. Each would be20–30 m long and would cost £1250 per metre.

Gabions Gabions have been used to protect therecreation ground built over the beach at themouth of the Shimna, where it enters DundrumBay in Newcastle. The first set had badlydecayed and were no longer proving effective,so in the regeneration programme during 2006they were replaced and a new footbridge built onthe stabilised coast to allow unrestrictedpedestrian access along the promenade.Gabions are more sustainable than rock armouror a sea wall as they allow water to enter eachcage and slowly dissipate the energy rather thandeflecting it back outwards.

Rock armourRocks may be used to control erosion byarmouring a dune face. They dissipate theenergy of storm waves and prevent furtherrecession of the backshore if well designed andmaintained. Rock armour is used widely in areaswith important backshore assets subject tosevere and ongoing erosion where it is not cost-effective or environmentally acceptable toprovide full protection using sea walls. This hasbeen used along various sections of DundrumBay. In the late 1990s, extensive rock armouringwas constructed to protect the Royal CountyDown Golf Course. This has provedunsustainable, as it is reducing the sedimentsupply for Murlough Bay, an Area of SpecialScientific Interest (ASSI).

Sea wallThe need for a sea wall came when Newcastleexperienced urban growth and the boardinghouses were built close to the coast for the seaviews. These new buildings at the time neededprotection from the high tides and waves. Thesea wall constructed in Newcastle is used assupport for the pedestrian walkway called apromenade.

The promenade in Newcastle thereforedoubles as a sea wall to protect the town.Following a severe storm in 2002, when the oldwall was partially washed away, the promenade

Coastal Management in the British Isles: Newcastle, Co. Down


and wall have been rebuilt and extended at acost of £4 million. The wall was raised by 1 mfrom the old Victorian level and now has acurved, wave return design to stop watersplashing over the wall.

Although this wall protects the builtenvironment, refracted waves appear to beincreasing beach erosion. Combined with a lackof material coming from further up the coast,this means that Newcastle is losing beach sand.So it is unsustainable. Indeed, studies show thatnorth of the Shimna River, the high tide beachhas been reduced due to promenadeconstruction.

The futureAlthough Newcastle's beach has been badlyeroded over the past 50 years, it remains

popular with locals and visitors from other partsof Northern Ireland. Each of the hardengineering measures is not singularly to blamefor this erosion, but such inappropriate anduncoordinated development along the coast hasincreased problems. It is no longer a naturallyfunctioning zone, where erosion and depositionare in balance. The Department of theEnvironment has recently announced anIntegrated Coastal Zone Management Strategyfor Northern Ireland that applies for 20 years(2006–26). In this groups are encouraged towork together towards a more sustainableapproach to coastal management. DownCouncil is considering building new groynes andeven beach nourishment in order to maintain awide and sandy stretch of beach at Newcastleto satisfy the demands of tourists.

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41� Figure 51 Newcastle as it is today

� Figure 50 This photograph of Newcastle harbour was taken in 1880


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1 Draw a timeline to show attempts to manage the coastline atNewcastle in Co. Down from Victorian times to the presentday. On your line mark specific dates and note the coastalmanagement scheme implemented.

2 Even with these various coastal management schemes thebeach at Newcastle has been badly eroded in the past50 years. Why do you think this has been the case?

3 Could the coastal management schemes implemented at Newcastle have been improved? What else could havebeen done?

Get Act ive

The big taskYou are going to work in groups to solve a mystery. Thequestion is: ‘Where has our beach gone?’ 1 Read the statements on page 43. 2 Access some photos and maps on the following websites:

• http://news.bbc.co.uk/1/hi/in_pictures/5246638.stm• http://picasaweb.google.com/olkenimages42/

NewcastleCountyDownNIreland#5235467851927876258• http://www.google.co.uk/maps and search for“Newcastle, County Down”.

3 Make some predictions as to what the answer to thequestion might be.

4 Read the statements and consider each piece of informationcarefully. Ask for clarification if there is anything you do notunderstand.

5 Look at and talk about the photos and the map.6 Use the statements to come up with an extended answer to

the original question (Remember, all the information may notbe relevant. Some ‘red herrings’ may have been included toconfuse you.) You can use any other knowledge you haveacquired in the study of this topic to piece together aconvincing explanation.

7 Pay attention to the time you have been given to completethe task.

8 Agree on a ‘best’ group answer.9 Select a group member to report the fully agreed answer to

the rest of the class in the feedback session.10 Individually, write an answer to the original question.

Get Act ive


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Unusual happenings at Dundrum Bay, County Down,have been puzzling local residents for some time.Reports of the beach at Newcastle disappearingwhile sand dunes at Ballykinler, across the bay, weregetting bigger and bigger, had locals and DownCounty Council stumped.

The beach in Newcastle is disappearing because ofglobal warming and climate change.

‘In the 1970s, our family spent many sunny Sundayafternoons on the sandy beach in Newcastle. It waslike a second home to our children.’ – Portadownresident.

Navigation charts from the nineteenth and twentiethcenturies show a substantial build-up of sandoffshore.

Computers have been used to simulate wavesmoving across the seabed. As sand builds up offshore, a marked change in how waves approach theshoreline can be observed.

In the mid-nineteenth century waves carried sand toboth ends of the bay, sustaining beaches atNewcastle and Ballykinler but now, the change inwave movement means that the sand is being carriedaway from Newcastle and toward Ballykinler instead.

Dr Andrew Cooper and Dr Fatima Navas, from theCentre for Coastal and Marine Research at theUniversity of Ulster, have discovered that naturalforces on the seabed are responsible for thepreviously unexplained changes.

Tourism has led to the eroding of Newcastle beach.

The sandy beach at Newcastle is really quite a thinveneer and a slight loss of sand exposes theunderlying glacial pebbles. This has a dramatic effecton the appearance of the shoreline.

‘Could the Minister of the Environment detail thesteps he is taking to prevent further erosion ofNewcastle beach.’ – Jim Wells, local MLA.

‘My wife and I have bought a new apartment close tothe seafront for our retirement. Our beautiful beachneeds to be saved and fully restored.’ – A retiredlawyer.

Experts believe the natural changes on the beachesof Dundrum Bay are not a cause for concern. Thereis plenty of sand in the system as a whole; the waveshave simply moved it away from Newcastle under thepresent conditions.

The result is the obvious physical changes that localpeople have noticed on their coastline: healthy,growing sand dunes at Ballykinler but diminishedvolumes of sand at Newcastle.

Air photographs of Newcastle beach taken in the1970s show a much greater covering of sand.

There is evidence that the seafloor changedsubstantially enough over a 150-year period for it toalter the wave patterns and for them to causechanges in the shoreline over the same timescale.

The amount of sand cover on the beach at any giventime reflects the balance between onshore sedimenttransport and sediment dispersal by long-shore driftand river currents.

Following a severe storm in 2002, when the old seawall was partially washed away, the promenade andwall were rebuilt and extended. The wall was raisedby 1 m from the original Victorian level and now has acurved, wave return design to stop water splashingover the wall. Although this wall protects the builtenvironment, refracted waves appear to be increasingbeach erosion.

A relatively wide beach has occurred at differentperiods in time adjacent to the mouth of the ShimnaRiver.

‘I have no powers to prevent the erosion ofNewcastle beach. I understand that studiescommissioned by Down District Council haveindicated that much of the erosion of sand from thebeach at Newcastle has been caused by theprogressive rock armouring of the sea front. Althoughtheses measures provide flood protection to thepromenade and the Newcastle centre, they arethought to have contributed to the problems of sanderosion.’ – Sam Foster, Minister of the Environment.

‘Our beach is useless for holidaymakers and daytrippers as it has become narrow, pebbly and poorlymaintained.’ – Owner of amusement arcade inNewcastle.

‘I am appalled to see the way the sea defences inNewcastle have been neglected over the years.’ –Local environmentalist.

The area of beach in Newcastle has been reduced bythe construction of the promenade, the sea wall infront of the Slieve Donard Hotel grounds and therock-armour revetments in front of the Royal CountyDown Golf Club.

Most of the sand lost from Newcastle beach hasbeen blown away by strong coastal winds in thewinter months.


Sample examination questions

1 The drainage basin: a component of the water cycle

Foundation Tier(i) Complete the following sentences by writing in one of the words from the list below.

The start of a river is called the _________________.

Precipitation is an _____________ to a drainage basin.

Water which is moving through ______________ is called through-flow.

A small river that joins the main river is called a _________________. [4]

(ii) Classify the following components of a drainage basin. One has been completed for you.

STORE IN TRANSFER IN THE DRAINAGE BASIN THE DRAINAGE BASIN

[4]

Higher Tier(i) Explain how rainfall becomes part of the groundwater flow within a drainage basin. [5]

(ii) State the meaning of the following terms:

• Watershed [2]• Confluence [2]

2 River processes and features

Foundation Tier(i) State if the following sentences about river processes are true or false.

[4]

Surface runoff

Interception byvegetation

Percolation

Through-flow

Infiltration

Soil Input Mouth Tributary Source

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Sentence True/False

Attrition is an erosional process

Deposition is more likely if the river’s load is small in size

Large rocks are mostly moved by suspension

Erosion means a river gets wider moving from source to mouth


(ii) Complete the key below with the labels on the diagram opposite to fully label awaterfall. [4]

Higher Tier(i) Describe two ways a river erodes.

Choose from the list below. [4]

Attrition AbrasionHydraulic action Solution

(ii) Explain the formation of floodplains. [4]

3 Coastal processes and features

Foundation Tier(i) Explain the difference between constructive and destructive waves. [2]

(ii) State the meaning of the term long-shore drift. [2]

(iii) Put the following coastal features into the order in which they would form from one another.

One has been done for you.

[3]

Higher Tier(i) With the aid of a diagram, explain how

long-shore drift works [6]

(ii) Explain the formation of stacks, like those shown in the picture to the right. [6]

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Key

Hard rock

Soft rock

Overhang

Plunge pool

A

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Feature Order

Stack

Crack 1

Arch

Cave


4 Sustainable management of rivers

Foundation Tier(i) For a named river you have studied, explain one reason

why it flooded.

River _________________ [1]Cause of flood [3]

(ii) Describe how flooding might affect people. [4]

(iii) Write out four types of hard engineering which might beused to reduce flooding. Choose your answers from the list below. [4]

Washlands Dams Levees Afforestation Flood walls

Straightening the river Land use zoning Storage areas

Higher Tier(i) For a named river you have studied, identify and

explain two reasons it flooded. [6]

(ii) Describe the possible impacts flooding could have onpeople and the environment. [6]

(iii) Evaluate the flood management strategies used on oneriver which you have studied. Remember this river mustbe from outside the British Isles. [7]

5 Sustainable management of coasts

Foundation Tier (i) Suggest two problems caused by a large number of

visitors to a beach. [2]

(ii) Describe how these problems could be solved. [4]

(iii) Explain why sea walls are not always built to protect an area of coastline. [3]

Higher Tier(i) Describe and explain two measures which might be

used to retain cliffs and beaches. [6]

(ii) Evaluate the extent to which a coastal managementstrategy, which you have studied, is sustainable. [9]

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