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TRANSCRIPT
This booklet includes: The Restless Earth
Coasts
Rivers on the Land
How to use this
Revision Guide...
WEEKS LEADING UP TO THE EXAM
1. READ through every section in the revision guide
2. LOOK at the exam tips and my predictions at the end of every section
3. HAVE A GO at answering some of the exam questions at the back of the guide
4. REMEMBER that CASE STUDIES in Geography are very important and will need a
lot of revising! (The information in this booklet is only the basics, use your
exercise books to revise the specifics)
5. DON’T PANIC Remember you have gone through all this information already,
although you may think you have forgotten some, once you look over it a few times
it will come back to you :)
6. TAKE TIME revise over a period of time which is suitable, although we all might
think we work best at the last minute this is not always the case)
7. PRACTICE your time management, see if you can answer 9 mark exam questions in
10minutes!
IN THE EXAM
1. READ THE QUESTION!!! (So many times I have seen people answer questions with
the EFFECTS of an event when the question is asking for the RESPONSES)
2. TAKE YOUR TIME do not rush through, make sure you have included enough detail
to achieve the best possible mark
3. DRINK water (Not too much you need a wee!)
4. DON’T LOOK at other people, everyone works at their own pace (plus, it wastes
time)
5. RUNNING OUT OF TIME? On a big question? Bullet Point the rest of your answer
NIGHT BEFORE/JUST BEFORE THE EXAM
1. Look over things once in the morning before the exam and once at night
2. Familiarise yourself with all your key facts
3. Enjoy a break and an early night
4. Any last minute problems, Miss Russell is in Hum3 for Form Time (come see me!)
Keyword Definition
Crust The Outer Layer of the Earth
Plate A Section of the Earth’s crust
Plate Margin The boundary where two plates meet
Mantle The dense, mostly solid layer between the outer core and the crust
Convection Currents The circular currents of heat in the mantle
Subduction The sinking of oceanic crust at a destructive margin
Collision The meeting of two plates of continental crust. They are forced together and
buckle under the pressure.
Fold Mountains Large mountain ranges where rock layers have been crumpled as they have been
forced together
Ocean Trenches Deep sections of the ocean, usually where an oceanic plate is sinking below a
continental plate
Composite Volcano A steep-sided volcano that is made up of a variety of materials, such as lava and
ash.
Shield Volcano A broad volcano that is mostly made up of lava
Subsistence farming Farming to provide food for the farmers own family
Terraces Steps cut into hillside to create an area of flatland
Irrigation Artificial watering of the land
Hydroelectric Power The use of flowing water to turn turbines to generate electricity
Natural Hazard An Occurrence over which people have little control, which poses a threat to
people’s lives and possessions. This is different from a natural event as volcanoes
can erupt in unpopulated areas without being a hazard.
Primary Effects The immediate effects of the eruption, caused directly by it.
Secondary Effects The after-effects that occur as an indirect effect of the eruption on a longer
timetable
Aid Money, food, training and technology given by richer countries to poorer
countries.
Earthquake A sudden and often violent shift in the rocks forming the earth’s crust, which is
felt at the surface.
Immediate
responses
How people react as the disaster happens and the immediate aftermath
Long-Term
Responses
Later reactions that occur in the weeks, months and years after the event.
Vent The opening- usually central and single- in a volcano, from which magma is
emitted.
Lahar These secondary effects of a volcanic eruption are mudflows resulting from ash
mixing with melting ice or water.
Supervolcano A mega colossal volcano that erupts at least 1,000km3 of material
Caldera The depression of the Supervolcano marking the collapsed magma chamber
Fissures Extended openings along a line of weakness that allows magma to escape
Geothermal Water that is heated beneath the ground, which water erupts into the air under
pressure.
Geyser A geothermal feature in which water erupts into the air under pressure
Hotspot A section of the earth’s crust where plumes of magma rise, weakening the crust.
These are away from plate boundaries.
A* Tip: When answering CASE
STUDY questions always include
at least 3 specific facts about
that event. E.g. During the 2004
Indian Ocean Tsunami the
effects included; around
300,000 people were killed, 2
million people made homeless
and many countries including
Somalia were hit by the wave.
Keyword Definition
Earthquake A sudden and brief period of intense ground shaking
Focus The point in the Earth’s crust where the earthquake originates
Richter Scale A logarithmic scale used for measuring earthquakes, based on scientific
recordings of the amount of movement
Epicentre The point at the earth’s surface directly above the focus
Shockwaves Seismic waves generated by an earthquake that pass through the earth’s
crust
Mercalli Scale A means of measuring earthquakes by describing and comparing the damage
done, on a scale of I to XII
Debt Money owed to others, to a bank or to a global organisation such as the World
Bank
The three P’s Prediction, protection and preparation
Prediction Attempts to forecast an event based on current knowledge
Protection Constructing buildings which will not collapse
Preparation Organising activities or drills so that people know what to do in the event of
an earthquake
Tsunami A special type of wave where the entire depth of the sea or ocean is set in
motion by an earthquake, which displaces the water above it and creates a
huge wave
A* Tip: Try to use keywords in
all exam answers 3 marks + as it
will help you to shorten your
answer and show the examiner
you have an extensive knowledge
of the topic.
EXAM TIPS FOR A
RESTLESS EARTH
Getting that C: Make sure you
know the definitions for the
keywords (not word for word)
just make sure you understand
what they mean!
A* Tip: It is very important to
correctly label your diagrams
when asked to draw one. It is
these rather than your
artistic capabilities which will
be tested.
Getting that C: Practice
drawing the diagrams you are
unsure of, make sure you have
all the key labels included.
Getting that C:
When answering
CASE STUDY
questions always
include at least 1
specific fact
about that event.
E.g. During the
2004 Indian
Ocean Tsunami
around 300,000
people were killed
REMEMBER: Revision is about picking out key information and
re-visiting it. If there is something you completely DO NOT
UNDERSTAND please ask your teacher to go through it again.
The structure of the Earth 1. The inner core is in the centre and is the hottest part of the Earth. It is solid and made
up of iron and nickel with temperatures of up to 5,500°C. With its immense heat energy,
the inner core is like the engine room of the Earth.
2. The outer core is the layer surrounding the inner core. It is a liquid layer, also made up
of iron and nickel. It is still extremely hot, with temperatures similar to the inner core.
3. The mantle is the widest section of the Earth. It has a diameter of approximately 2,900
km. The mantle is made up of semi-molten rock called magma. In the upper parts of the
mantle the rock is hard, but lower down the rock is soft and beginning to melt.
4. The crust is the outer layer of the earth. It is a thin layer between 0-60 km thick. The
crust is the solid rock layer upon which we live.
There are two types of Crust:
The Earth’s crust is made up of:
Oceanic Crust– Plates which carry sea
or ocean
Continental Crust– Plates which carry
land masses or continents.
The Location of
the world’s
Plates and Plate
Margins.
This map will help
you identify key
areas for volcanic
and earthquake
activity.
1 DESTRUCTIVE At Destructive Plates:
Two Plates meet (An Oceanic and a Continental)
The Oceanic plate is heavier and sinks below the
Continental Plate. This is called SUBDUCTION
The Oceanic Plate then melts and the magma
formed rises through the continental crust to
form a volcano.
The Andes is formed along a destructive margin
2 CONSERVATIVE At Conservative Plates:
Two Plates move past each other
FRICTION between the plates causes
earthquakes
The San Andreas Fault is a famous example
of a conservative plate boundary
3 CONSTRUCTIVE At Constructive Plates:
Two Plates move apart from each other
(Both Oceanic Plates)
Magma rises through the centre
Creates a gentle sloped SHIELD VOLCANO
The Mid-Atlantic ridge is an example of a
constructive plate boundary
KEY VOCABULARY
Destructive Plate Boundary
Constructive Plate Boundary
Conservative Plate Boundary
Inner core
Outer Core
Mantle
Crust
Subduction
Fold Mountains and Ocean Trenches
Fold mountains are mountains formed mainly by the effects of folding on layers within the upper part of the Earth's crust
Fold mountains are formed when two tectonic plates move together (a compressional plate margin). This can be where two continental plates move towards each other or a continental and an oceanic plate. The movement of the two plates forces sedimentary rocks upwards into a series of folds
Ocean trenches are the deepest part of the sea floor and are formed at the Subduction zone
1. FOLD MOUNTAINS
2. OCEAN
TRENCHES
Composite Volcano Shield Volcano
1 2
Magma Chamber
Magma Chamber
Eruptions from this volcano are infrequent but often violent
Eruptions from this volcano are frequent and non-violent
3. VOLCANOES
Tourism: Positive Impacts
Tourism is a positive effect with hill walking, attractive scenery, river rafting, and climbing attracting people. However, building tourist facilities such as hotels and restaurants is difficult due to the lack of flat land. Skiing is a popular tourist activity in winter.
Tourism: Negative Impacts
There can be a constant threat of avalanches in winter which have to be monitored with huge amounts of money being spent to combat the avalanche threat, especially where many tourists use the mountains. Tourists also bring congestion, litter and pollution problems.
Tourism is another major use of the Fold Mountains of the world. The increase in tourism has meant much-improved infrastructure, a huge increase in hotels and restaurants and the development of entire resorts. It has brought a large amount of much needed money into these areas and allowed local people to diversify from farming into many other jobs. Fold Mountains have a lot of other things to attract visitors. These include hill walking, the attractive scenery, river rafting, and climbing.
1. TOURISM
Farming is the main primary activity but often only cattle and sheep rearing is possible due to the very cold, wet climate, the altitude and steepness of the slopes. Agricultural machinery is difficult to use and there is a very short growing season. In mountains such as the Andes and Himalayas, terraces (steps) have been cut into the hillsides to allow crops such as vines and fruit to be grown.
The mountain slopes of the Andes are used for a variety of farming practises. The best land can be found on the valley floors, but an ingenious system of terraces dug into the valley sides and held up by retaining walls has been used to bring the lands on the valley sides into food production. The flat terraces help to hold up water in a region where there are marked shortages. Most crops are grown in the lower areas and include soya, maize, rice and cotton. However, the main staple crop of the Andes is the potato, and there are hundreds of different varieties found in the mountains. Most farming is subsistence, with the food grown for personal consumption, but there is some commercial farming.Llamas have historically been used a lot in the Andes, as a form of transportation and to carry goods. Alpaca, a relative of the Llama, has been used to produce some of the finest cloth known to man, and is also produced in the Andes mountains.
2. FARMING
Hydroelectric Power (HEP)The deep valley and rivers of the Andes give it huge potential as a region to produce hydroelectric power. The narrow valleys are ideal to dam as it cuts costs, and the steep relief increases water velocities allowing electricity generation. Snow melt fuels most of the water provision, but this means that HEP production can be reduced to small amounts in winter.
The Yuncan dam project dams the Puacartambo and Huachon rivers in northeast Peru, while the el Platinalproject will begin construction in 2009
Positive Impacts:Provides energy for many of the local areasNegative Impacts:Eyesore and area it is built requires to be flooded every year
Mining
The Andes mountains contains a rich mix of minable materials that are both very valuable and very useful to man. When the Spanish conquered South America their prime objective was to prospect for gold. Potosi in Bolivia was one of Spain's principle mines and produced lots of silver. There exist large deposits of Coal, oil and natural gas, iron ore, gold, silver, tin, copper, phosphates and nitrates and Bauxite (for aluminium) within the Andes mountains. The Yanacocha gold mine in Peru is the largest gold mine in the world. It is an open cast mine and the rocks containing the gold are blasted with dynamite. The rock is then sprayed with toxic cyanide and the gold extracted from the resulting solution. This can contaminate water supplies. The nearby town of Cajamarca has grown from 30,000 when the mine started to 240,000 people in 2005.
Positive Impacts:Provides jobs for the local people and money for the Peruvian economyNegative Impacts:Eyesore and adds to traffic into the area with the large lorries needed for transporting material
3. HYDROELECTRIC
POWER
4. MINING
April May 1980
A bulge was growing on the north flank.
May 18th at 8.32 a.m.
An earthquake occurs under the volcano and triggers a huge landslide.
May 18th at 8.33 a.m.
With the pressure released a huge lateral blast heads northwards
May 18th rest of the day
More and more ash shoots up high into the atmosphere. It gradually blows around the world.
How it happened!
EFFECTS OF THE ERUPTION
http://www.bbc.co.uk/schools/gcsebitesize/geography/natural_hazards/managing_hazards_video.shtml
PredictionTime lapse cameras in the crater allow geologists to make safe observations
Seismograms indicate what to look out for. They measure vibrations in the earths crust and measure the magnitude of earthquakes.
Tiltmeters detect a change in slope caused by shifting magma beneath the surface
GPS use satellites to detect minute movements over a larger area.
A detailed plan is needed for dealing with a possible eruption. Everyone who could be affected needs to know the plan and what they should do if it needs to be put into action. Planning for a volcanic eruption includes:• creating an exclusion zone around the volcano• being ready and able to evacuate residents• having an emergency supply of basic provisions, such as food• funds need to be available to deal with the emergency and a good communication system needs to be in place
Preparing for an Eruption
A Successful NHS poster showing the dangers of swine flu…
TASK: Produce an equally catchy slogan/mini poster (half a page in exercise book) to warn people of the signs of volcanic activity, and what to do if an eruption was to occur!
Supervolcanoes are not mountains – they form DEPRESSIONS within the
Earth’s crust. They begin with a column of magma rising through a vent
into the Earth’s crust. The magma gets stuck and pools, melting the
rock around for thousands of years. Over thousands of years the pres-
sure builds up and when the eruption eventually happens it drains the
magma lake and the land above collapse down over, creating a
CALDERA
Supervolcano A mega colossal volcano that erupts at least
1,000km3 of material
Caldera The depression of the Supervolcano marking
the collapsed magma chamber
KEY TERMS
CASE STUDY:
YELLOWSTONE
NATIONAL PARK
Yellowstone National Park is
located in parts of Wyoming,
Idaho and Montana. It is
located on a volcanic ‘hot spot’.
The last eruption was over
630,000 years ago.
Potential effects:
87,000 deaths
Large ash cloud covering
North America
Reduces global temperatures
Yellowstone
Why do Earthquakes happen?
The two plates at a plate margin cannot move past each other easily.
The two plates become locked. Friction causes pressure to build up.
Suddenly, the pressure is released and the plates jolt into a new
position. This causes seismic waves. The vibrations they cause are
called an earthquake
Focus is the point at which the rock
moves. The seismic waves
start at the focus.
Epicentre is directly above the focus on
the Earth’s surface.
KEY TERMS
How are Earthquakes measured?
The Richter Scale: This measures the
magnitude of a tremor (how powerful it is)
using an instrument called a seismograph. The
Richter Scale is measured on a scale from 1 to
10. It is a logarithmic scale which means that
a size ‘6’ on the Richter Scale is 10 times
more powerful than a size ’5’ and 100 times
more powerful than a size ‘4’.
Mercalli Scale. This measures the destruction
caused by an earthquake and is measured in
Roman Numerals I to XII (1-12)
THE THREE P’S!
Remember when talking
about the responses to
earthquakes:
Predict (using scientific
equipment e.g.
seismometers etc...)
Protect (Make buildings
earthquake-proof–
rubber foundations etc…)
Prepare (Earthquake
drills etc...)
KOBE EARTHQUAKE (1995) SICHUAN EARTHQUAKE (2008)
WHERE?:
JAPAN (RICH COUNTRY- MEDC)
WHERE?:
CHINA (POOR COUNTRY- LEDC)
WHY?: At 5.46am on 17th January
1995, the Philippines plate shifted
beneath the Eurasian plate along the
Nojima fault line that runs beneath
Kobe. 7.2 ON RICHTER SCALE
PRIMARY EFFECTS: Damage to
buildings. Many older buildings
collapsed completely. 300,000
homeless, 6,434 people killed (4,600
of them Kobe residents). Seriously
injured over 40,000.
SECONDARY EFFECTS: The most
devastating secondary effect was
fire. Paraffin heaters and gas
cookers set fire to buildings, Damage
= $220billion!, 30% of roads usable
RESPONSES: Friends and neighbours
searched through rubble for
survivors joined by the emergency
services when access was possible
Railways were 80% operational within
one month. Road network was fully
restored by July 1995
The Japanese practice an earthquake
drill every year to prepare them
WHY?: On 12th May 2008 at 2.28pm,
the pressure resulting from the Indian
Plate colliding with the Eurasian Plate
was released. This led to an earthquake
of 7.9 ON RICHTER SCALE
PRIMARY EFFECTS: Damage to
buildings (80% of buildings collapsed in
Beichuan). 5 million people were
homeless, 69,000 people killed (18,000
missing). Seriously injured over
374,000. Poor Housing materials blamed.
SECONDARY EFFECTS:
Communications were brought to a halt.
Neither land nor mobile phones worked
in Wenchuan. Roads were completely
blocked by landslides. Damage = $75
MILLION
RESPONSES: Troops parachuted in to
assess the situation in remote areas.
Others hiked on foot. On 14th May China
requested international help. Cash
donations were the preferred option.
The Chinese government pledged
$10million rebuilding fund and wrote off
debts owed by survivors
KOBE EARTHQUAKE, JAPAN (1995)
SICHUAN EARTHQUAKE, CHINA (2008)
What causes a tsunami? When an earthquake, volcano or landslide happens on the ocean floor, water
is displaced. This water forms the start of the tsunami.
When the waves reach shallower water:
their height can increase by several metres
the shallow water slows the wave
the waves get closer together
Tsunami A special type of wave where the
entire depth of the ocean is set in
motion by an event, often an
earthquake, which displaces the
water above it and creates a huge
wave
KEY TERMS
CASE STUDY: INDIAN OCEAN TSUNAMI (BOXING DAY 2004)
Two tectonic plates, the Australian and Eurasian plates,
meet just off Sumatra's south-west coast, grinding
together and sending periodic seismic tremors through the
region. At 0059 GMT a violent rupture occurred on the
sea floor along a fault about 1,000km long.
EFFECTS: 230,210 - 310,000 deaths, Two million people
were made homeless. People were swept away in the
waters, which arrived rapidly and with little warning. Thirteen countries were
affected, the worst being Indonesia. Indonesia was hit by the tsunami first.
Forty-five minutes later the tsunami reached Thailand. Islands reliant on
tourism and fishing, such as the Maldives, had to rebuild their industries
RESPONSES: Short-term aid, such as water purification tablets, temporary
housing and medical supplies were given from international countries.
An early warning system between countries surrounding the Indian Ocean has
been set up.
Keyword Definition
Climate The average weather conditions recorded over a period of the last 30 years
Weather The day-to-day conditions of the atmosphere
Convectional Rainfall Intense rainfall often in the form of thunderstorms resulting from very high tem-
peratures and rapidly rising and cooling air
North Atlantic Drift A Warm ocean current from the south Atlantic which brings warm conditions to the
west coast of the UK
Prevailing Winds The dominant Wind Direction
Maritime Influence The influence of the sea on the climate
Continentality The influence of being close to or far away from the sea
Insolation Energy from the sun used to heat up the earth’s surface
Depression An area of low atmospheric pressure
Front A boundary between warm and cold air
Warm Front A boundary with cold air ahead of warm air
Cold Front A boundary with warm air ahead of cold air
Occluded Front Front formed when the cold front catches up with the warm front
Warm Sector An area of warm air between a warm front and a cold front
Anticyclones An area of high atmospheric pressure
Frost Results from the temperature of the ground dropping below OoC
Fog Water that has condensed close to the ground to form low cloud and poor visibility
Extreme Weather A weather event such as a flash flood or severe snowstorm that is significantly
different from the average
Global Warming The recent trend showing an increase in global temperatures as a result of
Increasing greenhouse gas emissions.
Pleistocene Period A geological time period lasting from about 2 million years ago until 10,000 years
ago. Sometimes this period is referred to as the Ice Age
Greenhouse Effect The blanketing effect of the atmosphere in retaining heat given off from the
earth’s surface
Greenhouse Gases Gases such as Carbon Dioxide and methane which are effective at absorbing heat
given off from the earth.
Recycling Using materials such as aluminium and glass over and over again
Congestion Charging Charging vehicles to enter cities, with the aim or reducing the number of vehicles.
Kyoto Protocol An international agreement aimed at reducing carbon emissions from industrialised
countries
Carbon Credits A means of trading carbon between organisations or countries in order to meet an
overall target
Hurricane A powerful tropical storm with sustained winds of over 75mph.
Eye The centre of a hurricane where sinking air creates clear conditions
Eye Wall A high bank of cloud either side of the eye where wind speeds are high and heavy
rain falls
Track The Path or course of a Hurricane
A* Tip: When answering CASE
STUDY questions always include
at least 3 specific facts about
that event. E.g. During the 2004
Boscastle flash flood the
effects included; 58 buildings
flooded– most of which had to
be demolished, 25 business
properties destroyed this all
lead to a total rebuild cost of
over £15million.
A* Tip: Try to use keywords in
all exam answers 3 marks + as it
will help you to shorten your
answer and show the examiner
you have an extensive knowledge
of the topic.
EXAM TIPS FOR
CHALLENGES OF
WEATHER AND
CLIMATE
Getting that C: Make sure you
know the definitions for the
keywords (not word for word)
just make sure you understand
what they mean!
A* Tip: It is important that
you can read SATELLITE
MAPS and SYNOPTIC
WEATHER CHARTS. If you
feel you are unsure of these
please look over them again!
Getting that C: Look over
key areas that you are
unsure of, Weather and
Climate is a difficult topic
don't be afraid to ask for
help!
Getting that C:
When answering
CASE STUDY
questions always
include at least 1
specific fact about
that event. E.g. Dur-
ing the 2004 Bos-
castle Flash Flood
around 58 buildings
were flooded and
most had to be
demolished
REMEMBER: Revision is about picking out key information and
re-visiting it. If there is something you completely DO NOT
UNDERSTAND please ask your teacher to go through it again.
MISS RUSSELL’S PREDICTIONS FOR THIS TOPIC
There will be questions which ask you to either look at a satellite
map or synoptic weather chart and map OR a climate graph.
(Make sure you understand how to interpret these)
The largest mark question (6 mark FOUNDATION, 9 mark HIGH-
ER) will be on either EXTREME WEATHER, GLOBAL WARMING or
HURRICANES
(The extreme weather events in the UK have been a fairly ‘hot
topic’ in the media of recent)
Make sure you know your diagram for the GREENHOUSE EFFECT,
DEPRESSION and HURRICANES
Geography – Coasts Waves
Waves are usually formed by the wind blowing over the sea. Friction with the surface of the wa-
ter causes ripples to form and these develop into waves.
Waves can also be formed more dramatically when earthquakes or volcanic eruptions shake the
sea bed. These waves are called tsunamis.
As the water becomes shallower with the wave advancing on the beach, the circular motion of
the water becomes more elliptical. This causes the crest of the wave to rise up and then
eventually to topple onto the beach. The water that rises up the beach is called the swash.
The water that flows back towards the sea is called the backwash.
Constructive Waves
Constructive waves are waves that surge up the beach with a powerful swash.
They carry large amounts of sediment and ‘construct’ the beach, making it more extensive.
They are formed by distant storms, which can be hundreds of kilometres away. The waves are
well spaced apart and are powerful when they reach the coast.
Destructive Waves
Destructive waves are formed by local storms close to the coast.
They are closely spaced and often interfere with each other, producing a chaotic, swirling mass
of water. They rear up to form towering waves before crashing down onto the beach.
There is little forward motion (swash) when a destructive wave breaks, but a powerful backwash
which explains the removal of sediment and the destruction of the beach.
Types of Weathering
Mechanical weathering – involves the disintegration (breakup) of rocks without any chemical
changes taking place often resulting in angular fragments known as scree. Freeze-thaw
weathering is an example of mechanical weathering and has a particularly large impact on
the coast. Exfoliation is another example of mechanical weathering.
Chemical weathering – here, a chemical change occurs when weathering takes place. Rainwa-
ter, being slightly acidic, can slowly dissolve certain rocks and minerals. Carbonation and
solution where rock salts dissolve in water is an example of chemical weathering.
Biological weathering – this involves the action of flora and fauna. Plant roots are effective at
growing and expanding in cracks in the rocks. Rabbits may be effective by burrowing into
weak rocks and sands.
Mass Movement Processes
Both mass movement and weathering provide an input of material to the coastal system. Much of this
material is carried away by the waves to be deposited elsewhere along the coast.
Rockfall – the rapid, free-fall of rock from a steep cliff face. Rock fragments fall from the face
of the cliff because of the action of gravity. This is made worse by freeze-thaw action loos-
ening the rock. Bare, well-jointed rock is very vulnerable to rockfall - water enters the joint,
freezes and expands, cracking the rock. A scree slope of fallen rock is formed at the bottom
of the cliff.
Mudflow – occurs on steep slopes
over 10°. It's a rapid sudden
movement which oc- curs
after periods of heavy rain.
When there is not enough
vegetation to hold the soil in
place, saturated soil flows
over impermeable sub soil,
causing great devasta- tion
and endangering lives.
Landslides – are occasional, rapid movements of a mass of earth
or rock sliding along a concave plane. They can occur after periods of heavy rain, when the water sat-
urates overlying rock, making it heavy and liable to slide. Undercutting of a steep slope by river or sea
erosion weakens the rock above, also making a slump likely.
Rotational Slip – slump of saturated soil and weak rock along a curved surface.
Coastal erosion
When a wave crashes down on a beach or smashes down a cliff, it carries out the process of erosion. There are
several processes of coastal erosion:
Hydraulic power – this involves the sheer power of the waves as they smash onto a cliff. Trapped air is
blasted into the holes or cracks in the rock, eventually causing the rock to break apart. The explosive
force of trapped air operating in a crack is called cavitation.
Corrasion – this involves fragments of rock being picked up and hurled by the sea at a cliff. The rocks act
like erosive tools by scraping and gouging the rock.
Abrasion – this is the ‘sandpapering’ effect of pebbles grinding over a rocky platform, often causing it to
become smooth.
Solution – some rocks are vulnerable to being dissolved by seawater. This is particularly true of limestone
and chalk, which form cliffs in many parts of the UK.
Attrition – this is where rock fragments carried by the sea knock against one another, causing them to be-
come smaller and more rounded.
Transportation processes
As well as longshore drift, there are 4 other processes of transportation you need to know about:
Traction - This is where large particles like big boulders are rolled along the sea bed by the force of the
water.
Saltation - This is where pebble-sized particles are bounced along the seabed by the force of the water.
Suspension - This is where small particles like silt and clay are carried along in the water.
Solution - This is where dissolvable sediment is dissolved in the water and carried along. Coastal transportation, Longshore Drift
Waves follow the most common direction of the wind.
They usually hit the beach at a diagonal angle (or any angle that isn’t a straight right angle)
The waves swash carries sediment in the sea water up onto the beach in the same direction as the waves
i.e.: diagonally.
The waves backwash then carries the sediment back out to the sea at a right angle (in a straight line).
This creates a zig-zag pattern which transports sediment in the direction of the prevailing wind along the coast-
line.
Coastal Deposition
Coastal deposition occurs in areas where the flow of water slows down. Sediment can no longer be carried or
rolled along and has to be deposited.
Coastal deposition most commonly occurs in bays, where the energy of the waves is reduced on entering the
bay. This explains the presence of beaches in bays and accounts for the lack of beaches at headlands, where
wave energy is much greater.
Landforms resulting from Erosion
Stacks, arches, stumps and caves – These features are formed on cliffs or headlands. Waves attack vertical
lines of weakness in the rock known as faults. Processes such as hydraulic action and abrasion widen these
faults into cracks and eventually the waves penetrate deeply enough to create caves. Over time, the cave
will be eroded into an arch, accessible to the sea on both
sides. Weathering will also play a role, with physical weath-
ering processes such as freeze thaw and salt crystallisation
and chemical processes such as carbonation weakening the
rock surrounding the cave or arch making it more suscepti-
ble to mass movement and collapse. Finally, the erosion and
weathering continues and the arch collapses leaving behind
a stack (a vertical column of rock). These stacks can be at-
tack further and eventually the stack may collapse to leave a
low lying stump.
Bays and Headlands - In areas where the geology or rock type
runs at right angles to the coastline, bays and headlands can
be created. If there are alternating bands of harder and soft-
er rock running at right angles to the sea, the sea will erode
these bands at different rates (called differential erosion).
Hydraulic action, abrasion and corrosion are more effective
at eroding the softer rock, particularly during storms, and
this will erode further inland than the harder rock. During
calmer weather and no stormy periods, the hard rock will
absorb a lot of the wave energy and refract or bend the waves into the area with the softer rock, allowing
sediment to be deposited and accumulate as beaches. The net result of this over long periods of time is that
the hard rock is left jutting out to sea as a headland, and the softer rock is eroded into curved sand filled
bays.
Cliffs and wave-cut platforms – When waves break against a cliff, erosion close to the high tie line take a
‘bite’ out of the cliff to form a feature called a wave cut notch. Over a long period of time – usually hun-
dreds of years – the notch gets deeper until the overlying cliff cn no longer support its own weight and it
collapses. Through a continual sequence of wave-cut notch formation and cliff
collapse, the cliff line gradually retreats. In its place will be a gently sloping rocky platform called a wave cut
platform. A wave-cut platform is typically quite smooth but
may have some rock pools. During long periods of construc-
tive waves, the platform may become covered in sand or shin-
gle.
Pro- cess of Cliff Erosion
1. Weather weakens the top of the cliff.
2. The sea attacks the base of the cliff forming a wave-cut
notch.
3. The notch increases in size causing the cliff to collapse.
4. The backwash carries the rubble towards the sea forming
a wave-cut platform.
The process repeats and the cliff continues to retreat.
Landforms resulting from Deposition
Beaches – are accumulations of sand and shingle (pebbles
found where deposition occurs at the coast. Sandy beaches are
often found in sheltered bays, where they are called bay head beaches.
Spits – are long, narrow fingers of sand and shingle jutting out into the sea from the land. Spits are common
features across the world. As sediment is transported along the coast by longshore drift it becomes deposit-
ed at a point where the coastline changes direction or where a river mouth occurs. Gradually as more sedi-
ment is deposited, the feature extends into the sea. Away from the coast, the tip is affected by waves ap-
proaching from different directions and the spit often becomes curved as a result. Over time the sediment
breaks the surface to form new land and a spit is formed. It soon becomes colonised by vegetation with
grass and eventually trees growing. On the landward sheltered side of a spit where the water is calm, mud-
flats and salt marshes form, these are important habitats for plants and birds. Being close to sea level, spits
are vulnerable to erosion especially during storms.
Bars – Occasionally, longshore drift may cause a spit to grow right across a bay, trapping a freshwater lake or
lagoon behind it.
The Causes of rising sea levels
One of the effects of global warming is sea level rise. The IPCC suggests that a global sea level rise of 28 to
43cm will occur by the end of the century.
The main cause of sea-level rise is thermal expansion of the seawater as it absorbs more heat from the atmos-
phere.
The melting of ice on the land, from glaciers on Greenland, will increase the amount of water in the
oceans but scientists do not believe that this will significantly affect sea levels.
Since more than 70 per cent of the world’s population live on coastal plains, the effects of rising sea levels
are likely to be devastating.
Cliffs and Cliff retreat
A cliff is a vertical or sloping wall of rock or sediment that borders the sea.
Marine erosion processes attack the foot of the cliff and cause the erosion at a wave cut notch. Waves can
pound this area causing fragments to break off, and the water can also trap air in pore spaces, faults
and crevices, compressing the air which in turn exerts pressure on the rock causing it to break off.
This process is known as hydraulic action. Another process that occurs is corrasion, where sediment
and rocks in the sea water are hurled against the cliff face.
All three of these processes erode the wave cut notch at the base of the cliff undermining the whole struc-
ture of the cliff. These processes are variable and depend upon the fetch of the wave (the distance it
travels over open water), wind speed and how many storms there a year, but they are more or less
continuous over long periods of time.
At the same time that the base of the cliff is being eroded, the cliff face and its structure are being weak-
ened by sub aerial processes. Oxidation and carbonation are some of the chemical processes that can
weaken the structure of the rock, and depending upon the climate physical processes such as freeze
thaw and water layer weathering can take effect.
Over time this weakens the structure of the cliff face, and coupled with the erosion of the wave cut notch
at a critical point this cliff face will succumb to the influence of gravity and collapse in a process of
mass movement.
This material will then be carried away by the sea in the process of longshore drift by the transportation
process of solution, suspension, saltation and traction (depending upon the particle sizes).
Formation of salt marshes
A salt marsh begins life as an accumulation of mud and silt in a sheltered part of the coastline.
As more deposition takes place, the mud beings to breaks the surface to form mudflats.
Salt-tolerant plants such as Cordgrass start to colonise the mudflats. These early colonisers are called pioneer
plants.
As the level of the mud rises, it is less frequently covered by water. The conditions become less harsh as rain-
water begins to wash out some of the salt and decomposing plant matter improves the fertility of the newly
forming soil.
New plant species such as sea asters start to colonise the area and gradually, over hundreds of years, a succes-
sion of plants develop. This is known as a vegetation succession.
Coastal Defences
Hard engineering involves using articificial structures to control the forces of nature. For many decades peo-
ple have used hard engineering structures such as sea walls and groynes to try to control the actions of the
sea and protect property from flooding and erosion.
Soft engineering attempts to fit in and work with the natural coastal processes. They do not involve large arti-
ficial structures. Often more ‘low key’ and with low maintenance costs – both economically and environ-
mentally – soft engineering approaches such as beach nourishment are more sustainable. They are usually
the preferred option of coastal management.
Hard/
Soft
Description of how it works Advantages Disadvantages
Sea Walls HARD
Concrete or rock barrier to the sea
placed at the foot or cliffs or at the
top of a beach. Has a curved face to
reflect the waves back into the sea,
usually 3-5m high.
Effective at stopping the
erosion caused by the sea.
Often has a walkway or
promenade for people to
walk along.
Can be obtrusive and
unattractive to look at.
Very expensive and has
high maintenance costs.
Groynes HARD
Timber or rock structures built out
to sea from the coast. They trap
sediment being moved by longshore
drift, thereby enlarging the beach.
The longer beach acts as a buffer to
the incoming waves reducing wave
attack at the coast.
Results in a larger beach,
which can enhance the
tourist potential of the
coast. Provide useful
structures for people inter-
ested in fishing. Not too
expensive.
In interrupting long-
shore drift, they starve
the beaches downdrift,
often leading to in-
creased rates of erosion
elsewhere. Groynes are
unnatural and rock
groynes in particular
can be unattractive.
Rock Armour HARD
Piles of large boulders dumped at
the foot of a cliff. The rocks force
waves to break, absorbing their en-
ergy and protecting the cliffs. The
rocks are usually brought in by
barge to the coast.
Relatively cheap and easy
to maintain. Can provide
interest to the coast. May
sometimes be aesthetical-
ly pleasing. Often used for
fishing.
Rocks are usually from
other parts of the coast-
line or even from
abroad. Can be expen-
sive to transport. They
do not fit with the local
geology. Can be very
obtrusive.
Beach nour-
ishment
SOFT The addition of sand or shingle to
an existing beach to make it higher
or broader. The sediment is usually
obtained locally so that it blends
with the existing beach material.
Usually brought onshore by barge.
Relatively cheap and easy
to maintain. Blends in
with existing beach. In-
creased tourist potential
by creating a bigger
beach.
Needs constant mainte-
nance unless structures
are built to retain the
beach.
Dune regener-
ation
SOFT
Sand dunes are effective buffers to
the sea yet they are easily damaged
and destroyed, especially by tram-
pling. Marram grass can be planted
to stabilise the dunes and help them
to develop. Areas can be fenced to
keep people off newly planted
dunes.
Maintains a natural envi-
ronment that is popular
with people and wildlife.
Relatively cheap.
Time-consuming to
plant the marram grass
and fence off areas.
People do not always
respond well to being
prohibited from access-
ing certain areas. Can
be damaged by storms.
Marsh crea-
tion
SOFT
This involves allowing low-lying
coastal areas to be flooded by the
sea to become salt marshes. This is
an example of managed retreat. Salt
marshes are effective barriers to the
sea.
A cheap option compared
to maintaining expensive
sea defences that might be
protecting relatively low-
value land. Creates a
much-needed habitat for
wildlife.
Land will be lost as it is
flooded by sea water.
Farmers or landowners
will need to be compen-
sated.
Managed re-
treat
SOFT
Allowing controlled flooding of low
-lying coastal areas of cliff collapse
in areas where the value of the land
is low.
It is a real option if there
is a high risk of flooding
or cliff collapse and where
the land is relatively low
value.
Causes loss of land and
the destruction of cer-
tain habitats and biodi-
versity.
Salt-tolerant plants such as Cordgrass start to colonise the mudflats. These early colonisers are called pioneer
plants.
As the level of the mud rises, it is less frequently covered by water. The conditions become less harsh as
rainwater begins to wash out some of the salt and decomposing plant matter improves the fertility of the
newly forming soil.
New plant species such as sea asters start to colonise the area and gradually, over hundreds of years, a suc-
cession of plants develop. This is known as a vegetation succession.
Coastal Defences
Hard engineering involves using articificial structures to control the forces of nature. For many decades
people have used hard engineering structures such as sea walls and groynes to try to control the actions
of the sea and protect property from flooding and erosion.
Soft engineering attempts to fit in and work with the natural coastal processes. They do not involve large
artificial structures. Often more ‘low key’ and with low maintenance costs – both economically and en-
vironmentally – soft engineering approaches such as beach nourishment are more sustainable. They are
usually the preferred option of coastal management.
Case Study – Rising Sea Levels , The Maldives
Global warming is caused by an increase in CO2 and other greenhouse gases as a result of burning of fossil
fuels for industry, electricity and transport.
Rising global temperatures will result in thermal expansion (as the water gets warmer it will expand so sea
level will rise) and ice caps will melt resulting in more water in the sea.
Location
In the Laccadive Sea, about 700 kilometers south-west of Sri Lanka and 400 kilometers south-west of India.
Economic Impacts
Tourism 28% GDP and 60% foreign earnings would be greatly affected
The vast majority of government revenue (approximately 90 percent) comes from import duties and tourism-
related taxes.
Most tourist accommodation is on the low lying coasts / beaches. These are increasingly vulnerable to storms
and will have to be moved if sea levels rise.
Round the capital, a 3m high wall at cost of $63 million (borrowed from Japan) which has to be repaid.
The IPCC estimates that global warming will result in warmer winters in the northern regions of Europe and
North America. This could lead to a decline in tourism in the Maldives as residents of Europe and North
America no longer travel to the Maldives to escape the harsh winters.
The airport is about 1m above sea level. It could be threatened by higher tides. If it could not be used regular-
ly most economic activity from tourism to import of food would be severely affected.
Social Impacts
Sea level rise would mean homes and hotels then jobs would disappear.
If sea levels rose by 1m, 365 000 people would have to be evacuated and resettle in countries like Sri Lanka and
India.
People rely on fishing for income. With rising sea levels the marine ecosystems will change and so will the
number of fish available
The Asian tsunami of December 26, 2004 killed 82 people, displaced an additional 12,000 and caused extensive
damage to the country's important tourism industry.
If extreme events occur more frequently people will become reluctant to visit the area.
Environmental Impacts
IPCC estimates that average global sea levels will rise by between 0.09m and 0.37m Along with rising sea lev-
els, increased beach erosion, more powerful storms, higher storm surges, and threats to biodiversity are
among the major threatens to the Maldives due to climate change over the coming decades.
The Maldives are comprised of nearly 1,200 islands and atolls in the Indian Ocean. The combined land mass of
all the islands is 115 square miles-- which less than 2m above sea level at its highest point.
More natural disasters such cyclones will affect the islands.
Case Study – Area of Salt Marsh , Keyhaven Marshes
Location and Background
Formed in the lee of Hurst Castle spit, Hampshire, United Kingdom.
Supports a range of habitats including grassland, scrub, salt marsh and reed beds.
Nationally recognized as an important site for wildfowl and wading birds.
Problems
Retreating by up to 6m a year - further sea-level rise threatens a ‘squeeze’ of the salt marsh as it lies between a
low sea wall built in the early 1990s and the encroaching sea.
Salt marsh under threat from breaching of Hurst Castle spit during severe storms. In December 1989, storms
pushed part of the shingle ridge over the top of the salt marsh, exposing 50-80m to the full fury of the sea.
It was eroded in less than 3 months.
Increasing demands for leisure and tourism mean increasing numbers of people wish to visit the marshes. Care-
ful management is require to prevent damage by trampling, parking and pollution. The area is popular with
mariners who use the many creeks to moor their boats.
Management
In 1996 rock armor and beach nourishment were used to increase the height and width of the spit to stop breach-
ing. Since completion of the £5m sea defenses, the spit hasn’t been breached and the Keyhaven Marshes
seems protected.
Location and Background
The Holderness Coast is on the East Coast of England.
Highest rates of erosion in Europe with an average of 1-2m per year going as high as 20m per year in some are-
as especially south of Mappleton.
Since Roman times, 4 km has been lost – 29 villages have fallen into the sea.
Management and Impact
In 1991, the Council spent nearly £2 million building 2 large rock groynes and rock armor to protect the village of
Mappleton so they didn’t have to spend money rebuilding an important road.
These Groynes trapped beach sediment and was therefore successful in protecting the road and village of Mapple-
ton.
However, down the coast there was no longer any beach so the cliffs were exposed and rates of erosion dramati-
cally increased up to 10m/year.
Impact on people’s Lives and Environment
In 1991, the Council spent nearly £2 million building 2 large rock groynes and rock armor to protect the village of
Mappleton so they didn’t have to spend money rebuilding an important road.
These Groynes trapped beach sediment and was therefore successful in protecting the road and village of Mapple-
ton.
However, down the coast there was no longer any beach so the cliffs were exposed and rates of erosion dramati-
cally increased up to 10m/year.
As the amount of beach is reduced so landslides, rotational slips and cliff collapse becomes more frequent.
This leads to changes in the environment and the ecology – some surface land will be lost but new minerals will
brought to the surface.
Caravan’ sites relocating may improve the environment as they return to their natural state.
Case Study – Problems of Cliff Collapse , Holderness Coast
Name Minehead
Location North coast of Somerset
Purpose Hard Coastal Defences
Background One of the region’s premier tourist resorts Home to a large Butlin’s resort - visited by many thousands of tourists every year By early 1990s it became clear that current sea defences were inadequate for the future Storm damage was estimated to be £21m if nothing were done Environment Agency developed a plan to defend the town and improve the amenity value Work started in 1997 and the sea defences were officially opened in 2001, costing £12.3m, a
Features 0.6m high sea wall with a curved front to deflect the waves. It has a curved top to deter people
from walking on it and its landward side is faced with attractive local red sandstone Rock Armour at the base of the wall to dissipate some of the wave energy Beach Nourishment (sand) to build up the beach by 2m in height. This forces the waves to
break further out and provides an excellent sandy beach for tourists 4 rock groynes to help retain the beach and stop longshore drift moving sand to the east A wide walkway with seating areas alongside the sea wall. This is popular with tourists and lo-
Result This scheme has been extremely successful Not only does it protect the town from storms and high tides, but it has also enhanced the sea-
front by creating an attractive beach environment
Name Wallasea Island
Location Formed at the confluence of the River Crouch and River Roach in Essex
Purpose Soft Coastal defences
Background Low-lying coastal island protected from the sea by a ring of embankments Until recently it has been mostly used for growing wheat
Features With the north coast defences falling into disrepair, the government decided to realign the
northern part of the island by constructing a new embankment inland and allowing the old
sea defences to be breached The new mudflats and salt marsh will help to protect the new sea wall and offer additional
Result The £7.5m scheme aims to replace bird habitats lost to development, improve flood defences
on the island and create new leisure opportunities In July 2006 the old sea wall was breached in 3 places to allow 115ha of land to be flooded Eventually the flooded area will contain islands and a number of salty lakes Much of it will revert to salt marsh providing a much-needed breeding ground for birds Since 2007 the site has been managed by the RSPB
Source: Where a
river starts.
Tributary: A smaller
river that flows into
the main channel.
Watershed: The
boundary between
two drainage basins
Confluence: The
point where two
rivers join.
Mouth: The end
of a river.
RIVER DRAINAGE BASIN
Key Point
Rivers are channels of water which drain the land’s surface. They erode, transport and
deposit materials, creating steep valleys and wide floodplains.
Source Middle Mouth
Large / Angular Bedrock
Narrow / Shallow channel
Flow slowed by friction
Eroded bedrock – smoother
and smaller
Channel wider and deeper
Less friction so faster flow
Eroded bedrock –
smoother and smaller
Deep and wide channel
Little friction resulting in a fast flow
Bedrock eroded into fine
silt and sand
RIVER LONG PROFILE
Key Point
A River Long Profile is usually shown as a sloping curve like this ->
RIVER LANDFORMS
RIVER LANFORMS RESULTING FROM EROSION
WATERFALL 1. Waterfalls are formed where the river flows
from harder rock onto softer rock
2. The weaker, softer rock is eroded by abrasion
and hydraulic action, undercutting the hard rock
whilst deepening the plunge pool.
3. Eventually the over hanging hard rock will
collapse due to a lack of support, causing the
waterfall to move back.
4. This process has happens again and again, as
the waterfall retreats upstream a steep rocky
valley is created, known as a gorge.
RIVER LANFORMS RESULTING FROM EROSION AND DEPOSITION
MEANDER
OX-BOW LAKE
form when meanders loop back on themselves (forming an almost closed curve). Erosion cuts through the narrow
meander neck whilst deposition blocks off the entrance to the old meander, separating the ox-bow lake from the river.
1. As the river erodes laterally, to the right side then the left
side, it forms large bends, and then horseshoe-like loops called
meanders.
2. The formation of meanders is due to both deposition and
erosion and meanders gradually migrate downstream.
3. The force of the water erodes and undercuts the river bank
on the outside of the bend where water flow has most energy
due to decreased friction.
4. On the inside of the bend,
where the river flow is slow-
er, material is deposited, as
there is more friction.
RIVER LANFORMS RESULTING FROM DEPOSITION
FLOODPLAINS AND LEVEES FLOODPLAIN
In a river’s middle course lateral erosion causes
the river’s meanders to migrate. As the river
erodes and deposits is creates an area of flat
land, known as a floodplain. When a river floods,
water inundates this flat area and deposits a
covering of silt. Over time thick layers of silt
can build-up leading to the creation of alluvium
soil. As the river moves towards its mouth, it
meanders more and more and the floodplain
becomes larger and larger.
LEVEES
form during times of flood. As the river leaves
its channel there is a sudden loss of energy,
resulting in the river depositing much of its load
immediately next to the main channel. Overtime
this deposition builds up creating a natural
embankment called a levee.
Exam Question: Explain the
formation of ox-bow lakes (6
marks).
Grade A Response
Due to erosion (abrasion) on the out-
side and deposition on the inside,
meanders migrate over their flood-
plain. In places they migrate to-
wards each other, forming a mean-
der neck. The neck is eventually
eroded creating a faster, straighter
route for the river. As little water
now flows around the loop, deposi-
tion blocks off the old bend, forming
a oxbow lake.
Level 3 – 6 marks. Refers to the
entire process and includes a number
of subject specific terms.
Exam Question: Explain the formation
of ox-bow lakes (6 marks).
Grade C Response
Where two meanders migrate towards
each other they eventually create a nar-
row piece of land called a neck. The riv-
er erodes through the neck creating a
new straight route. The old bend is
called an oxbow lake.
Level 2 – 4 marks. Response lacks
geographical terms and is incomplete,
failing to explain how the old meander
bend becomes separated from the river.
MODEL EXAM
ANSWERS
KEYWORD DEFINITION
PRECIPITATION ANY SOURCE OF MOISTURE REACHING THE GROUND
INTERCEPTION WATER BEING PREVENTED FROM REACHING THE SURFACE BY TREES
SURFACE STORAGE WATER HELD ON THE GROUND SURFACE
INFILTRATION WATER SINKING INTO SOIL/ROCK FROM THE GROUND SURFACE
SOIL MOISTURE WATER HELD IN THE SOIL LAYER
PERCOLATION WATER SEPING DEEPER BELOW THE SURFACE
GROUNDWATER WATER STORED IN THE ROCK
TRANSPIRATION WATER LOST THROUGH PORES IN VEGETATION
EVAPORATION WATER LOST FROM GROUND/VEGETATION SURFACE
SURFACE RUN-OFF WATER FLOWING ON TOP OF THE GROUND
THROUGHFLOW WATER FLOWING THROUGH THE SOIL LAYER PARALLEL TO THE SURFACE
GROUNDWATER
FLOW
WATER FLOWING THROUGH THE ROCK LAYER PARALLEL TO THE SURFACE
WATER TABLE CURRENT UPPER LEVEL OF SATURATED ROCK/SOIL WHERE NO MORE WA-
TER CAN BE ABSORBED
STORM HYDROGRAPH The peak rainfall is the time of highest
rainfall. The peak discharge (the time when
the river reaches its highest flow) is later
because it takes time for the water to find
its way to the river (lag time) . The normal
(base) flow of the river starts to rise
(rising limb) when run-off, ground and soil
water reaches the river. Rock type,
vegetation, slope and situation (ie is this an
urban river?) affect the steepness of this
limb. The falling limb shows that water is
still reaching the river but in decreasing
amounts. The run-off/discharge of the riv-
er is measured in cumecs - this stands for
cubic metres per second. Precipitation is
measured in mm - this stands for
millimetres.
FACTORS AFFECTING RIVER DISCHARGE
FACTOR EXPLANATION
RELIEF THE STEEPNESS OF THE LAND AFFECTS HOW QUICKLY WATER CAN
REACH THE RIVER CHANNEL. (FASTER FLOW– STEEPER LAND)
TEMPERATURE AFFECTS THE LOSS OF WATER FROM THE DRAINAGE BASIN AND
THEREFORE THE LEVEL OF DISCHARGE. WHEN TEMPERATURES ARE
HIGHER THERE IS GREATER LOSS VIA EVAPORATION.
IMPERMEABLE ROCK IMPERMEABLE SURFACES DO NOT ALLOW WATER TO INFILTRATE
THEREFORE THERE IS GREATER SURFACE RUN-OFF
DEFORESTATION IF TREES ARE REMOVED, WATER REACHES THE SURFACE FASTER
AND THE TREES ARE NOT INTERCEPTING OR TAKING WATER FROM
THE GROUND.
URBANISATION EXPANDING TOWNS CREATE AN IMPERMEABLE SURFACE. THIS IS
MADE EVEN WORSE BY BUILDING DRAINS TO TAKE THE WATER
AWAY FROM BUILDINGS QUICKLY– AND QUICKLY INTO THE RIVERS!
EXAM TIP
You are expected to be able to construct, describe and
explain hydrographs. A hydrograph shows two graphs -
rainfall (in bars) and discharge (in a line).
Top AQA Examiners Tip
‘‘Ensure that you can explain how physical and
human features and processes can
affect the amount of water flowing in rivers’’
Impermeable (Hard) Rock:
Under the soil so the rain cannot soak through
Hard Dry Soil:
When the soil is baked hard in summer the rain runs over.
Wet Soil:
When the soil is full of water no
more rain can soak through.
Steep Slopes:
Rain will run down a steep slope quickly
Cut down trees:
Leaves slow rainfall and roots take in water.
Buildings:
Rain cannot soak through tarmac and pavements
Factors that increase the risk of flooding
Physical Factors
Severe weather such as heavy or
continuous precipitation (rainfall)
is the most common cause of river
flooding in the UK.
Impermeable surfaces, such as
baked or saturated soil, increases
surface flow and the amount of
water entering the river system.
Snow melt in spring can lead to
flooding in mountainous regions
where thick layers of snow have
built-up over the winter.
In upland areas with steep
gradients there is little time for
water to infiltrate into the soil,
shortening lag time.
Human Factors
In wooded areas trees may intercept rainfall,
trapping rainwater on their leaves. Additional
rainwater may be absorbed by their roots and
released back to the atmosphere through
transpiration. When forests are cut down
(deforested) less rainwater is intercepted and
transpired so more water reaches the river and
gets their quicker.
In urban areas, the landscape is made up of
mainly impermeable surfaces. As rainfall is
unable to penetrate the surface, water flows
into the drains and directly to the river. Sloping
roofs also increased run-off and reduce surface
storage.
Changing farming techniques have lead to
increased surface runoff. Up-and-down
ploughing channels rainwater quickly downhill
shortening lag time.
The extensive use of fossil fuels and changing
farming practices, have increased the amount
of greenhouses (e.g. carbon dioxide and me-
thane) in our atmosphere. These gases ‘trap-
in’ the sun’s heat warming our climate. Higher
global temperatures have lead to an increase in
extreme weather conditions, such as hurricanes
and droughts, and increasingly unpredictable
rainfall patterns.
REMEMBER:
PHYSICAL: Things
created by nature
HUMAN: Things created
by people
Facts & Figures:
-Other areas affected by flooding in July included
Warwickshire, Shropshire, Worcestershire, Bed-
fordshire, Oxfordshire and Berkshire.
-Total cost of July floods was £6 billion.
CAUSES What Caused the Flooding?
-The ground was already saturated
-On 21 July 83mm of rain fell in a few hours (3
times average for July).
-Heaviest rain fell on Tewkesbury and Evesham
-River Severn burst its banks.
-Much of the valley is low lying so flood waters
quickly spread.
-Much development on the flood plain of the river
so little infiltration could take place.
-Drains became blocked so water could not run-off.
Key Words and Terms
-rainfall
-saturated
-contaminated water
-floodplains
-burst banks
-emergency response
-relief aid
-water treatment
-bowsers
-flood defences
EFFECTS
What were the effects of the flooding?
-Over 350 000 people lost access to running water
for 2 weeks.
-Water supplies were contaminated with sewage.
-Homes and hospitals also lost electricity supply.
-On the night of 21 July thousands of motorists
were stranded on the M5. Rail passengers were
also stranded at Gloucester station.
-3 people died. Two men died trying to pump water
out of Gloucester Rugby Club.
-Thousands of people were forced to leave their
homes. Belongings were lost and damaged.
-many were trapped in their homes and had to be
rescued by boat or helicopter.
-Water treatment works closed.
-Increase in cost of milk, bread and meat as farm-
ers were unable to meet demand from consumers.
-increased debate about the wisdom of building on
floodplains.
RESPONSES
How did the authorities respond?
-RAF Rescue helicopters scrambled to rescue peo-
ple from roof tops (emergency response).
-Fire and Rescue services rescued people and
pumped water from flooded buildings.
-Flood Relief Fund set up to raise money for house-
holders (relief aid).
-Severn Trent Water Company brought 50m litres
of bottled water in. Also moved 1300 water bow-
sers and 100 tankers into area.
-Severn Trent donated £3.5m to communities most
affected.
-The Mythe Water Treatment works was repaired
restoring water to most homes by the end of July.
-Other water companies sent tankers to affected
area.
-British Red Cross sent food parcels to community
centres where homeless residents were sheltering.
-Governmental review into flood defences set up.
-Visits to the area by the Prime Minister and Prince
Charles.
Tewkesbury is in
Gloucestershire in the
South West of England
PHYSICAL CAUSES OF THE FLOODING
HUMAN CAUSES OF THE FLOODING
FACTFILE
Bangladesh is one of the world's poorest and least
developed nations in the world
Population: 131,269,860 (July 2001 est..)
Main language: Bangladeshi version of Bengali:
‘Bangla’
Infant mortality rate: 69.85 deaths per 1,000 live
births (2001 est..)
Life Expectancy: 60.54 years
People per doctor: 12,500
Literacy: 56%
Unemployment rate: 35.2% (1996)
Percentage of population with access to safe
water: 97%
70% of Bangladesh is less than
1m above sea level
Over 57% of the land was destroyed by floodwater
THE EFFECTS OF THE FLOODING
THE RESPONSES OF THE FLOODING
Bangladesh GNP: $380 PER PERSON
Flood Protection Measure
Type Hard Soft
Strategy Dams River Channel
Modification
Afforestation Washlands
Benefits 1. Discharge regu-
lated – floods pre-
vented;
2. HEP potential;
3. Recreation oppor-
tunities.
1. Straightening
and deepening the
channel allows a
large amount of
water to flow
quickly through
the river.
1. Intercepts rain-
fall;
2. Holds soil in
place reducing
erosion;
3. Relatively cheap;
4. Creates
habitats for
wildlife;
5. Recreation
opportunities.
1. Allowing some
parts of the river
to flood naturally
reduces risk in
urban areas;
2. Flooding leads
to marshlands –
important
ecosystems.
Drawbacks 1. Expensive;
2. Sediment trapped
possibly leading to
problems
downstream;
3. Spoils the view
4. Flood prevention
may lead to fertility
problems.
1. Expensive;
2. May require
regular
maintenance;
3. Destructions of
habitats;
4. Un-natural look;
5. Moves flood
risk downstream.
1. Floods still
occur;
2. Large areas of
land needed;
3. Forests need to
be carefully man-
aged to maximise
effect.
1. Floods still oc-
cur;
2. Productive
farmland may be
lost;
3. Local residents
may have to move.
CASESTUDY FLOODING MANAGEMENT: THREE GORGES DAM, CHINA
WHY WAS IT NEEDED? In 1988 huge floods in china caused chaos!! The
floods left a clay sediment over all the fields making the soil less fertile.
The cost of those floods were 500 million. The Chinese government
(communist) decided to built a dam up the river Yangtze to control the
floods. It is the biggest dam in the world. The dam wall is 2335 meters
long and 185 meters high, the maximum water level is 150 meters high. It
is also 115 meters wide on the bottom and 40 meters wide on top. It is to
be finished in 2009 and the total cost of the project will add up to around
15 billion.
THE IMPACTS?
ECONOMIC: The dam is a multi-purpose project built to prevent flooding AND create HEP.
The HEP station will generate electricity equivalent to 18 nuclear power stations. 14 % of China’s power.
Stopped flooding from a 1 in 10 year event to a 1 in 100 year event
ENVIRONMENTAL: 100 river dolphins left in the area as dam has destroyed habitat, 60,000 hectares of fertile
farmland will be flooded
SOCIAL:828 religious cultural and archaeological sites will be flooded including important Buddhist carvings 66% of
Wanxian city will be flooded. Some 900 factories and 250000 people will have to move
The UK manages its water supply and demand problems. It does this by:
Transferring water from areas of surplus to areas of deficit. (For example Wales
transports water to Liverpool)
Fixing leaky pipes means less water is lost by transfer.
Build more reservoirs to store more water.
Reduce amount of water used.
Encouragement of water meters..
In the UK, the supply and demand for water
differs.
On average the annual rain in the UK shows that Scot-
land, the north of England, the west of England and
Wales have the largest amount of precipitation on av-
erage each year.
On average the population density shows how many
people are in each area. Scotland, Wales and the north
of England have low population densities.
This means basically these areas are water surplus.
This means that that on average, the high population
areas have a water deficit, and the low population are-
as have water surplus.
CASE STUDY WATER MANAGEMENT IN UK: LAKE VYRNWY AND DAM
LOCATION: River Vyrnwy is located in Powys, central Wales
FACTS: - a Traditional solution to unequal water supply, there is
an area of water surplus (Wales) and an area of
water deficit (Liverpool)
Construction of dam and pipeline began in 1881 and
completed in 1888. First stone dam in the UK.
SOCIAL ISSUES: New village had to be built 3km from the original called Llanwddyn. Original
Village flooded: 2 chapels, 3 inns, 10 farmhouses and 37 houses demolished
ECONOMIC ISSUES: Loss of farmland and livelihoods
ENVIRONMENTAL ISSUES: Loss of wildlife habitats
SUSTAINABLE SUPPLIES: Transfer schemes are expensive. Building dams is a hard
engineering strategy. Local schemes are more sustainable.
Processes of river erosion
Hydraulic action: force of the water Abrasion: sand, boulders erode channel Attrition: load breaking up smaller pieces Solution: some rocks dissolve in river water
Processes of transportation
Traction: boulders roll along river bed Saltation: small pebbles bounced along Suspension: sand / silt carried in flow Solution: dissolved minerals carried away
Valley long and cross profiles
Upper course long profile: irregular, steep Lower course: lower, smoother, less steep Upper course cross profile: steep V shape Lower course: gentle V shape, flat
Landforms of river erosion
Mainly found in upper course Waterfalls, gorges, interlocking spurs Formed by vertical erosion River cutting down towards sea level
Formation of waterfall and gorge
Alternate outcrops of hard and soft rocks Hard is eroded slowly, soft is eroded fast Soft rocks undercut by water splashback Waterfall retreats upstream, leaving a gorge
Landforms of river deposition
Mainly found in lower course Levées, flood plains, deltas River carries a large load of sediment Deposited where water flow slowed down
Formation of meander and ox-bow lake
Outside bend: strong flow, erosion, cliff Inside bend: weak flow, slip-off slope Meander size increased by lateral erosion Narrow meander neck broken in a flood
River discharge
Volume of water flowing in a river Factors: the weather, rock type, relief High discharge after heavy, prolonged rain Particularly impervious rock, steep slopes
Causes of flooding
Physical: factors favouring high discharge Wet weather before; ground is saturated Snow melts, cool weather, little evaporation Human: deforestation, building construction
Hard engineering strategies
Structures built to prevent flooding Dams and reservoirs Concrete / stone channel sides Raising the height of river banks
Soft engineering strategies
Measures to reduce the scale of flooding
Plant trees on steep valley sides
Zoning: stop more building on flood plains
Issue flood alerts; prepare e.g. sandbags
Water supply in the UK
Water surplus: north and west of UK High precipitation, lower population density Water deficit: south and east England Lowest precipitation, highest population
REVISION FLASHCARDS: WATER ON THE LAND
1. Using examples, describe some of the hazards of living on a
destructive plate margin (4) Foundation
2. Using an example, outline the impact of a major earthquake on
people and property in the developing world (9) Higher
3. Describe 2 ways in which buildings in developing countries can
be made more resistant to earthquakes (2)
4. Explain how preparation and prediction could reduce tectonic
hazards (volcanoes and earthquakes) (4)
5. Explain why some areas are more vulnerable than others (4)
6. Explain the role magma plays in shaping shield volcanoes (2)
7. How do tectonic plates move? (2)
8. Outline the responses made by a country to reduce the risk of
future earthquakes. (9 marks HIGHER/6 mark FOUNDATION)
9. Using a diagram describe how volcanoes are formed along
destructive plate margins (4 marks)
10. Using an example, Describe the potential impacts of a
supervolcanic eruption (6 marks)
11. Using a case study outline the impacts of a tsunami on a land
and its community (6 marks FOUNDATION/9marks HIGHER)
TRY some of these exam questions on lined paper or in your
exercise books. Bring them to revision sessions and lessons if
you would like them to be marked by your class teacher!
TRY some of these exam questions on lined paper or in your
exercise books. Bring them to revision sessions and lessons if
you would like them to be marked by your class teacher!
1. Describe the difference between weather and climate (2 marks)
2. Using a diagram describe the passing of a depression (5 marks)
3. Using case studies describe how anticyclones can have differing
affects on UK weather (4 marks)
4. Using an example describe the impacts of an Extreme UK weath-
er event (6 marks FOUNDATION/9 marks HIGHER)
5. What is the evidence for climate change? (3 marks)
6. Draw a diagram of the greenhouse effect (4 marks)
7. Using specific examples outline some of the impacts of global
warming across the world (5 marks)
8. Explain what is being done by countries at an international level
to combat the effects of global warming (6 marks FOUNDA-
TION/9marks HIGHER)
9. Using a diagram explain the formation of a hurricane (5 marks)
10. ‘Hurricanes can cause different effects on countries at differ-
ent levels of development’. Using examples outline evidence to sup-
port this statement (6 marks FOUNDATION/9marks HIGHER)
1. What is the difference between the long profile and the cross
profile of a river? (2 Marks)
2. Explain why the upper course of a river valley has a different
cross profile from the lower course. (4 Marks)
3. Name and describe two other processes by which material is
transported in Rivers. (4 Marks)
4. Deposition occurs when rivers slow down. Why do Rivers Slow
down? (4 Marks)
5. Using a Diagram Explain the formation of a River cliff. (3 Marks)
6. Using a Diagram Explain the formation of an ox-bow lake. (6
Marks)
7. Describe, using a diagram the formation of Waterfalls. (6 Marks)
8. What is a flood plain? (1 Mark)
9. What are levees? and explain how they are formed (3 Marks)
10. Explain what the following terms mean:
i) Peak discharge ii) Lag time (2 Marks)
11. Describe and compare the primary and secondary effects of
flooding in an MEDC and in an LEDC. (6 Marks)
12. What is meant by hard and soft engineering strategies?
(2 Marks)
13. Give two ways in which the supply of water in the UK can be
managed. (2 Marks)
14. Describe the economic, social and environmental impact of a
studied Reservoir (8 Marks)
TRY some of these exam questions on lined paper or in your
exercise books. Bring them to revision sessions and lessons if
you would like them to be marked by your class teacher!