16

Coastal Processes, Landforms and Issues

Key questions:

1. What natural processes are taking place at the coast?

2. How do these processes effect humans living by the coast?

3. How are coastal landforms created?

4. How do we make use of coastal landforms?

5. How can we manage coastal areas and landforms in a sustainable way?

6. How have coastal processes affected the Holderness coast and how have they been

managed?

Key vocabulary:

Erosion: the wearing away of the landscape.

Sustainable: capable of being maintained into the future for further

generations to enjoy.

Permeable rock: rock which allows water to soak through.

Impermeable rock: rock which does not allow water to soak through.

Processes and landforms of coastal erosion

There are four types of erosion which take place along the coastline. These are:

Hydraulic action – water crashes into lines

of weakness in the cliff, pushing air further

into the gap and forcing the rock apart.

Abrasion - when rocks within the water are

pushed into the cliff face by the force of the

waves and knock other pieces of rock off the

cliff.

17

Attrition - when rocks within the water are moved about due to the

movement of the waves, they hit against each other knocking bits off and

becoming smaller and smaller, as well as more rounded.

Corrosion - when weak acid or salt within the sea water dissolves the rock on the side of the

cliff. Rocks such as chalk are particularly susceptible to this kind of erosion.

Erosion causes a number of coastal landforms; these landforms often attract many tourists:

Headlands and bays: Bays are areas of soft rock that have been eroded more quickly than

areas of hard rock which then stick out into the sea as headlands.

Crack: these are formed at weak spots within the rock.

Cave: as cracks eroded further they form caves.

Arch: If a cave is formed in a headland it may break through to the other side forming an

arch.

Stack: If the roof of an arch collapses it will form a stack.

Stump: As the waves attack the foot of the stack it will eventually topple over leaving only a

small short rock form called a stump.

Activity:

On the diagram below label the landforms of erosion.

18

As cliffs are eroded they retreat further back into the land. Cliff retreat also leads to a

number of landforms being created such as wave-cut notches and platforms.

Softer areas or rock, such as bays, suffer from erosion (predominantly abrasion) from the

sea but also from above.

As the waves attack from below so rain soaks into top permeable layers making them heavy

and unstable. These types of cliff are very unstable and dangerous to walk across.

Permeable sand

based rocks

Wave attack

Impermeable clays

Abrasion

Direction

of slumping

19

Processes and landforms of transportation and deposition

Long shore drift: this is the main type of transportation which takes place along the coast.

It takes place when the waves hit the beach at an angle, the swash (water from a wave

travelling up the beach) takes material up the beach at an angle and then the backwash

(water from a wave returning to the sea) takes the material back to the sea at a right angle

to the coast line due to gravity. Material is the moved in the direction that the waves hit the

beach at (normally the direction of the prevailing wind).

Deposition – this is when material which has been eroded and then transported is dropped by

the sea. It can build up into a number of different landforms.

Landforms of deposition are all formed due to the deposition of material like rocks and sand.

Spit: Spits form when long shore drift

carries material across a bay and to

the end of a headland. The material is

then deposited at the end of the

headland and as more and more is

deposited the sandy area starts to

stick out away from the headland. If a

spit forms at a river estuary the

movement of the river water travelling

to towards the sea will stop the spit

from protruding out too far.

Bar: If a spit forms from a headland and

there is no river there to stop the

deposition it is possible for the spit to

join two headlands together and cut the

bay and beach off from the sea. This is

called a bar.

20

Tombolo: If a spit forms from a

headland with an island close by it could

join the island to the mainland. This is

called a tombolo.

Activities:

Use the aerial photograph below to

complete the activities.

1. On the map

draw an arrow to

show the

direction of long

shore drift and

circle the two

spits.

2. Explain how you decided on this as the direction of long shore drift.

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

Coastal Management

People living on the coast are increasing vulnerable to coastal erosion. A variety of methods

have been put into place to reduce the impacts of coastal erosion.

Name of management type

Description Advantages Disadvantages

Sea wall

A concrete wall built along the back of a beach or on sea front.

Effective at reflecting waves, lasts a long time.

Expensive, ugly, reflects energy does not absorb it, leads to erosion of material in front of wall, can prevent access to beach.

21

Revetments

Large rock or concrete boulders placed at back of beach or on sea front.

Absorbs waves energy, lasts a long time, effective.

Expensive, un-aesthetically pleasing, can prevent access to beach, dangerous to walk on.

Gabions

Small stones and rocks held together in wire mesh placed at back of beach or on sea front.

Absorbs wave energy, cheaper than other options, vegetation can grow on them over time.

Doesn’t last a long time (small stones are eroded within mesh), Can prevent access to beach.

Groynes

Wooden or rock structures which stick out into the sea to prevent long shore drift taking beach sand away.

Very effective at stopping long shore drift, wooden groynes cheaper than other options, help to keep the beach benefitting tourism there.

Stops sand being transported down the coast leading to more erosion down the coast, sand will build up at groyne and need to be re-dispersed.

Beach nourishment

Sand material is added to making a larger beach to help slow waves.

Soft engineering, helps create large beach which encourages tourism, material will benefit areas down the coast as it is transported there.

Needs to be regularly topped up as sand it transported away through LSD. Problems sourcing the sand.

Off shore reef

Tyres or rocks are placed in a band off shore making the water shallower and making the waves break earlier.

Soft engineering, is using old tyres can be cheaper option, reefs attract fish and can be used for diving, also means waves hitting beach are smaller and safer for bathers.

Shallow areas unsafe for some shipping, if using tyres there is a chance of them breaking off the reef and being taken away into the sea, makes waves smaller which will stop surfing.

Planting vegetation

Grass is planted in sand dunes to hold sand in place.

Soft engineering, cheaper option, encourages wildlife there.

Not appropriate for many areas, prevents sand being transported by LSD to other areas.

Managed retreat Coastline is left to retreat due to erosion but the area is monitored for safety and people evacuated from danger zones.

Soft engineering, cheaper option, doesn’t impact on coast further down.

Loss of homes and businesses. Buildings need to be removed before cliff collapses.

All of the above methods can be classified into hard and soft engineering.

Hard engineering are methods which try to prevent natural processes (e.g. erosion),

examples would include sea wall, revetments and gabions.

Soft engineering are methods which try to encourage natural processes (e.g. waves breaking

and slowing), examples include beach nourishment, planting vegetation and managed retreat.

Unfortunately most coastal management methods have severe impacts further down the

coastline. As less material is eroded of transportation is stopped to beaches further down

the coast are diminished. Beaches act as natural protection to the cliffs beyond, slowing the

waves down before they reach the cliff or stopping them from reaching the cliff all together.

Therefore as beaches are destroyed this leads to increased erosion at these places.

22

Activities:

1. Name one type of soft engineering and explain the advantages and disadvantages of this as

a form of coastal management.

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

2. Use the photo opposite to answer the

following.

a) What two forms of coastal

management are in place?

______________________________

______________________________

b) Explain why the erosion has increased

on the East side of the photo.

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

Extra c) Suggest another form of coastal management for the West side of the photo that

would not create an increase in erosion on the East side of the photo. Explain your choice.

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

N

23

Coastal erosion, landforms and management on the Holderness Coast – Case Study

The Holderness Coast is located on the North-East coast of England; it is one of the fasted

eroding coastlines in Europe due to its soft geology.

The soft boulder clay that

makes up most of the area

is easily eroded and then

the material is transported

southwards due to long

shore drift. This has led to

the formation of Spurn

head at the mouth of the

Humber. Towards to

North of the coastline

Flamborough head is make

up of harder chalk as many

attractive landforms of

erosion are found here.

Spurn head attracts a large number of tourists to this area; it is

one of the UK best examples of a spit being over three miles long.

The whole area is protected as a nature reserve (many rare

species living in the salt marshes behind) and the spit is part of

the UK Heritage coastline. It provides jobs in local cafes and

souvenir shops along with hotels. However it is under threat by

increasing coastal management further up the coastline. As

residential areas such as Mappleton are protected there is less

eroded material being transported to replenish the spit.

Chalk stack

at

Flamborough

Head

Chalk arch at

Flamborough

Head

24

Example of the impacts of Coastal Management: Mappleton

The village of Mappleton is greatly underthreat by coastal erosion along the coastline and by

1998, the main road running through the village was only 500m from the cliff top and in

places it is now only 50m. The village is under threat due to the easily eroded boulder clay

(glacial till) which makes up the cliff line. The area suffers from erosion rates of up to 2m

per year.

Protecting Mappleton - To reduce the amount of erosion threatening Mappleton, 2 rock

groynes were constructed in 1991 to encourage the build up of beach in front of Mappleton

by trapping longshore drift. This meant that that waves would break on the beach rather

than attacking the cliffs.

Problems for further down coast - Those living south of Mappleton village have experienced

the 'knock-on' effects of the coastal management.

25

Exam Practice – 2007 and 2003

1. Study the photo below from the Great Ocean Road in Australia.

a) Explain how this coastal

landform was created. You may

use diagrams if you wish.

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

__________________________________________________________________(4)

b) Explain why tourists are attracted to coastal areas like the Great Ocean Road.

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

__________________________________________________________________(4)

2. a) What do you understand by the terms ‘erosion’ and ‘deposition’?

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

___________________________________________________________________(2)

26

b) Study the photograph below.

i) Draw an

outline map

of the area

and label

the

following on

it;

Salt marsh

Sand and

shingle

(3)

ii) Give one example of photo evidence that people have used this landform.

_____________________________________________________________________

_____________________________________________________________________

____________________________________________________________________(1)

27

3. CASE STUDY: Coastal landforms.

For a named coastal landform describe how the landform was created and explain how it is

being used and affected by people. Use diagrams if required.

Named coastal landform: __________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

___________________________________________________________________(8)

28

Flooding

Key questions:

1. How are floods caused?

2. What are the effects of flooding?

3. How can the risk of flooding be managed?

4. What were the causes and effects of the floods of the River Severn

in 2000 and how has it since been managed?

5. What were the causes and effects of the floods on the River Ganges in

1998 and how have it since been managed?

Key vocabulary:

Delta: A river formation at the mouth (where river meets the sea) of a

river where deposition causes new land to be formed.

Discharge: The amount of water flowing through a river, measured in

cubic metres per second (cumecs).

Groundwater flow: The flow of water through rocks.

Hydrograph: A graph showing the discharge of a river over time.

Causes of flooding

The main cause of flooding is high levels of rain fall over a short period of time.

Rock type can affect the chances of flooding. Areas with impermeable rocks will be more at

risk from flooding and the ground will not soak up the rain.

Urbanisation leads to more surfaces being made impermeable due to use of concrete. Water

runs off quickly into gutters and reaches rivers much quicker.

Vegetation cover will decrease the chances of flooding as the plants will take up the water

through their roots.

Tsunamis can cause devastating coastal flooding, tsunamis are caused by earthquakes which

happen at sea and create giant waves.

Strom surges also lead to coastal flooding. This is where a strong storm lifts up the sea

water and causes sea levels to rise temporarily.

29

Deforestation means trees are cut down to create more farm land, this increases the risk of

flooding as there is less vegetation to take up the water.

Relief of the land; steep valley sides means rain water runs into the river in a short space of

time. The river does not have time to deal with such a large amount of water in a short space

of time.

Activity

1. Sort out the causes of flooding above into natural and human causes.

Natural Human

Extra 2. Explain how climate change can lead to increasing frequencies of serious flooding.

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

Flood hydrographs

Flood Hydrograph show how a river's discharge responds following a period of heavy rainfall.

On a hydrograph, the flood is shown as a peak above the base (normal) flow of the river.

River discharge does not respond immediately to rainfall inputs as only a little of the rainfall

will fall directly into the channel. The river will start to respond initially through inputs from

surface runoff (the fastest flow of water) and its discharge will later be supplemented

through inputs from throughflow and groundwater flow.

30

Effects of flooding

Short term effects include:

Loss of life Crop damage Roads closed

Water

borne

diseases

spread

Businesses

forced to

shut

Electricity

cuts

Long term effects include:

People’s homes remain ruin

for many months

Lack of future investment in

area

House and business insurance

rises or is refused

Activity

Sort the effects above into economic and social. Create a key to show your categorisation.

31

Flood prevention

Type of management Advantages Disadvantages

Damn – water is held back

against a damn wall and only

released when the river has the

capacity for it.

Can also be used to create

electricity. Very reliable at

reducing flooding.

Very expensive, prevents the deposit of

minerals from river into farm land,

flooding behind damn can lead to

settlements being lost, danger of damn

breaking.

Levees – banks built along the

side of the river to enlarge its

capacity.

Fairly cheap method. Prevents water re-entering the river

when rain stops.

Tree planting – Trees are planted

to soak up excess water from

rain.

Fairly cheap method. Provides

more trees which gives habitats

and takes up CO2. Soft

engineering favoured by

environmentalists.

Takes time for trees to be established.

Can only soak up a finite amount of

water.

Dredging – material removed

from river channel to higher its

water capacity.

Simple way to increase the

amount of water a river can

carry.

Needs to be done regularly to keep

channel deep. Can lead to greater

flooding down steam as water arrives

there quicker.

Straightening / widening river

channels - river is made wider

and channels straighten.

Allows water to move quickly out

of urban areas where effects

from flooding would be high.

Can lead to greater flooding down steam

as water arrives there quicker.

Flood plain clearance – keeping

flood plains free from housing

and business so damage from

floods in minimal.

Soft engineering method. Allows

land at flood plain to be used for

parks and farm land.

Reduced land available for housing. Does

not stop the actual flood so can still be

dangerous to people in the area.

Sand bags – bags of sand handed

out to households at risk of

flooding, will hold back water

from seeping under doors.

Can be given out when needed.

Fairly cheap method. Can be

targeted to people at risk.

Not that effective in stopping water from

entering homes. Only a short term

solution.

Activity

1. Sort out above management strategies into hard and soft engineering options (review

meanings from coastal management if needed). Create a key to show your categories.

Extra 2. How are the water levels of the River Trent controlled (it is not one of the above!)?

_____________________________________________________________________

_____________________________________________________________________

32

Flooding on the River Severn in 2000 – Case study

The River Severn begins in the Cambrian Mountains in

Wales and flows out through England and the Bristol

Channel. It is the longest river in Great Britain.

Some of the most serious effects of the 2000 floods

were felt in the tourist town of Bewdley.

Flooding on the River Ganges 1998 – Case study

Causes:

Highest levels of rainfall in over 270 years

Location in the West of the UK close to Wales

leads to high levels of rainfall all year round

Land use – urban land use on the banks of the

river, further afield mostly farm land, little

forest

Dredging ceased in the 1950s due to high costs

Climate change blamed for increase in stormy

weather conditions

Narrow river channel in Bewdley

Effects:

Insurance costs rise

140 homes flooded –damage

to buildings

Loss of income for the area

from tourism and

agriculture

Loss of personal belongings

for residents

Transport links cut off

Flood prevention:

Due to the effects of the flooding shown above the

government saw the need to put in flood defence

mechanisms.

The chosen method was a 2.7 metre high

demountable flood wall.

It acted in a similar way to levees, increasing the

amount of discharge the river could carry before if

would flood the outside areas.

The wall was made demountable so it was not an

eyesore to tourists when there was no flood risk.

It can be erected in 24hours

It dramatically reduced the potential effects of

the high river levels in 2007. Without the wall the

town would have flooded severely again.

The net benefits of the wall were calculated to be

£0.6 million following an initial cost benefit

analysis.

Go to the following web pages for

more…

http://www.geography.org.uk/resour

ces/flooding/bewdley/whathappened

Bewdley during

2000 and 2007

floods.

33

Exam practice – 2003

Background

Between July and September 1998, Bangladesh

suffered one of its worse ever floods. Despite being

flooding being common in this country, the floods of

1998 were particularly severe resulting in over 1000

deaths and 30 million people being made homeless.

Background

Between July and September 1998, Bangladesh

suffered one of its worse ever floods. Despite being

flooding being common in this country, the floods of

1998 were particularly severe resulting in over 1000

deaths and 30 million people being made homeless.

Background

Between July and September 1998, Bangladesh

suffered one of its worse ever floods. Despite being

flooding being common in this country, the floods of

1998 were particularly severe resulting in over 1000

deaths and 30 million people being made homeless.

Background

Between July and September 1998, Bangladesh

suffered one of its worse ever floods. Despite being

flooding being common in this country, the floods of

1998 were particularly severe resulting in over 1000

deaths and 30 million people being made homeless.

Physical causes

Bangladesh is a low lying country with 70% of

its land at less than 1m above sea level and 80%

being on the floodplain of the Ganges and

Brahmaputra rivers.

Bangladesh is set on the drainage basins of

the rivers Ganges and Brahmaputra and so is at risk

of both these rivers flooding.

Bangladesh has a monsoon climate meaning

heavy annual rains which often result in the rivers

exceeding their carrying capacity.

In spring melting snow from the Himalayas

further increases the amount of water in the two

rivers and the chance of flooding.

Human causes

Population increase in Bangladesh, Nepal and

India has led to more deforestation.

Deforestation in areas of Nepal and India

further upstream means that less water is intercepted

and more ends up in the rivers.

Deforestation has also led to more erosion

upstream leading to silt being carried downstream.

This is then deposited in the channel later on

reducing the amount of water it can carry.

Bangladesh is an LEDC and has high national

debt. It therefore has little money to spend on flood

defences and protection methods.

Effects

Over two thirds of the land was underwater

including Dhaka covered by 2m.

30 million made homeless with many more

damaged homes.

Official death toll of 1, 070. Deaths caused by;

drowning, contamination of water leading to

water board diseases e.g. cholera, lack of

access to medical care for non-flood related

conditions due to break down of transportation.

Food supplies severely affected as farm land

an crops are flooded.

Economy suffers as businesses and factories

are flooded, 20% drop in exports.

Transportation cut off in many areas leading to

relief efforts not being able to reach areas.

Short term response

International food aid.

Volunteers and aid agencies try to rebuild flood defences in case of further flooding.

Make shift medical centres set up.

Possible long term solutions

Creation of more levees (embankments which raise sides of river increasing its channel capacity.

Constructing flood protection shelters in higher land to shelter people and animals in times of emergency.

Emergency flood warning systems and plans to be put in place and practiced annually.

Providing medical stores in villages.

Building flood proof storage shelters for food and emergency supplies.

34

1. Study the map and news item below.

Maximum and minimum discharge of the Parana River 1951-2001 (at Corrientes)

a) How did the maximum discharge of the Parana River change between 1951 and 2001?

Refer to figures in your answer.

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

___________________________________________________________________(2)

35

b) Choose two of the causes given for increased flooding in the news article. For each cause,

explain why it could increase flooding on the Parana River.

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

___________________________________________________________________(4)

c) Study the map below which shows the location of Resistencia.

i) What is being done to protect the town from flooding?

_____________________________________________________________________

_____________________________________________________________________

____________________________________________________________________(1)

ii) Suggest two other ways of protecting the town from flooding. Explain how each would

work. ________________________________________________________________

36

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

___________________________________________________________________(4)

2. Case study: A place where a serious flood has affected people and the environment.

Name a place where you have studied a serious flood. Describe how the flood affected

people and the environment. Explain what people could do or have done to prevent flooding

from affecting them in the future.

Named place: ___________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

___________________________________________________________________(8)