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! 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!) 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 Keyword Crust Plate Plate Margin Mantle Convection Currents Subduction Collision Fold Mountains Ocean Trenches Composite Volcano Shield Volcano Subsistence farming Terraces Irrigation Hydroelectric Power Natural Hazard Primary Effects Secondary Effects Aid Earthquake Immediate responses Long-Term Responses Vent Lahar Supervolcano Caldera Fissures Geothermal Geyser Hotspot Definition The Outer Layer of the Earth A Section of the Earth’s crust The boundary where two plates meet The dense, mostly solid layer between the outer core and the crust The circular currents of heat in the mantle The sinking of oceanic crust at a destructive margin The meeting of two plates of continental crust. They are forced together and buckle under the pressure. Large mountain ranges where rock layers have been crumpled as they have been forced together Deep sections of the ocean, usually where an oceanic plate is sinking below a continental plate A steep-sided volcano that is made up of a variety of materials, such as lava and ash. A broad volcano that is mostly made up of lava Farming to provide food for the farmers own family Steps cut into hillside to create an area of flatland Artificial watering of the land The use of flowing water to turn turbines to generate electricity 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. The immediate effects of the eruption, caused directly by it. The after-effects that occur as an indirect effect of the eruption on a longer timetable Money, food, training and technology given by richer countries to poorer countries. A sudden and often violent shift in the rocks forming the earth’s crust, which is felt at the surface. How people react as the disaster happens and the immediate aftermath Later reactions that occur in the weeks, months and years after the event. The opening- usually central and single- in a volcano, from which magma is emitted. These secondary effects of a volcanic eruption are mudflows resulting from ash mixing with melting ice or water. A mega colossal volcano that erupts at least 1,000km3 of material The depression of the Supervolcano marking the collapsed magma chamber Extended openings along a line of weakness that allows magma to escape Water that is heated beneath the ground, which water erupts into the air under pressure. A geothermal feature in which water erupts into the air under pressure A section of the earth’s crust where plumes of magma rise, weakening the crust. These are away from plate boundaries. 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 The point at the earth’s surface directly above the focus Epicentre Shockwaves The three P’s Seismic waves generated by an earthquake that pass through the earth’s crust A means of measuring earthquakes by describing and comparing the damage done, on a scale of I to XII Money owed to others, to a bank or to a global organisation such as the World Bank 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 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 Mercalli Scale Debt Tsunami 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: 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. 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. EXAM TIPS FOR A RESTLESS EARTH 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 Getting that C: Practice drawing the diagrams you are unsure of, make sure you have all the key labels included. 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. 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: 3 CONSTRUCTIVE 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 At Constructive Plates: KEY VOCABULARY Destructive Plate Boundary Constructive Plate Boundary Conservative Plate Boundary Inner core Outer Core Mantle Crust Subduction 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 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 1. FOLD MOUNTAINS Ocean trenches are the deepest part of the sea floor and are formed at the Subduction zone 2. OCEAN Fold mountains are formed when two tectonic plates TRENCHES 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 3. VOLCANOES Composite Volcano Shield Volcano Eruptions from this volcano are infrequent but often violent Eruptions from this volcano are frequent and non-violent 1 2 Magma Chamber Magma Chamber 1. TOURISM 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. 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. 2. FARMING 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. 3. HYDROELECTRIC POWER Positive Impacts: Provides energy for many of the local areas Negative Impacts: Eyesore and area it is built requires to be flooded every year 4. MINING Positive Impacts: Provides jobs for the local people and money for the Peruvian economy Negative Impacts: Eyesore and adds to traffic into the area with the large lorries needed for transporting material 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 Platinal project will begin construction in 2009 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. How it happened! 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. EFFECTS OF THE ERUPTION Prediction Time 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. http://www.bbc.co.uk/schools/gcsebitesize/geography/natural_hazards/ managing_hazards_video.shtml Preparing for an Eruption 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 A Successful NHS poster showing the dangers of swine flu… KEY TERMS Supervolcano Caldera A mega colossal volcano that erupts at least 1,000km3 of material The depression of the Supervolcano marking the collapsed magma chamber 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 pressure builds up and when the eruption eventually happens it drains the magma lake and the land above collapse down over, creating a CALDERA Yellowstone 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 KEY TERMS 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. 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 THE THREE P’S! 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) 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, JAPAN (1995) KOBE EARTHQUAKE (1995) WHERE?: JAPAN (RICH COUNTRY- MEDC) SICHUAN EARTHQUAKE, CHINA (2008) SICHUAN EARTHQUAKE (2008) 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 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. Many older buildings collapsed completely. 300,000 homeless, 6,434 people killed (4,600 of them Kobe residents). Seriously injured over 40,000. 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: The most devastating secondary effect was fire. Paraffin heaters and gas cookers set fire to buildings, Damage = $220billion!, 30% of roads usable 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: 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 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 KEY TERMS 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 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 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 Prevailing Winds Intense rainfall often in the form of thunderstorms resulting from very high temperatures and rapidly rising and cooling air A Warm ocean current from the south Atlantic which brings warm conditions to the west coast of the UK 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 Recycling A weather event such as a flash flood or severe snowstorm that is significantly different from the average The recent trend showing an increase in global temperatures as a result of Increasing greenhouse gas emissions. 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 The blanketing effect of the atmosphere in retaining heat given off from the earth’s surface Gases such as Carbon Dioxide and methane which are effective at absorbing heat given off from the earth. 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 Hurricane An international agreement aimed at reducing carbon emissions from industrialised countries A means of trading carbon between organisations or countries in order to meet an overall target 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 The Path or course of a Hurricane North Atlantic Drift Global Warming Pleistocene Period Greenhouse Effect Greenhouse Gases Carbon Credits Track 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: 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. 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. EXAM TIPS FOR CHALLENGES OF WEATHER AND CLIMATE Getting that C: When answering CASE STUDY questions always include at least 1 specific fact about that event. E.g. During the 2004 Boscastle Flash Flood around 58 buildings were flooded and most had to be demolished 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! 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! 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 HIGHER) 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 water 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. Rainwater, 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 loosening 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 occurs 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 devastation 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 saturates 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 become 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 coastline. 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 weathering 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 susceptible 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 attack 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 softer 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 hundreds 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 constructive waves, the platform may become covered in sand or shingle. Process 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 deposited at a point where the coastline changes direction or where a river mouth occurs. Gradually as more sediment is deposited, the feature extends into the sea. Away from the coast, the tip is affected by waves approaching 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, mudflats 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 atmosphere. 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 structure 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 weakened 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 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 succession 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 environmentally – soft engineering approaches such as beach nourishment are more sustainable. They are usually the preferred option of coastal management. Sea Walls Hard/ Soft HARD Description of how it works Advantages Disadvantages 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. 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. Effective at stopping the erosion caused by the sea. Often has a walkway or promenade for people to walk along. Results in a larger beach, which can enhance the tourist potential of the coast. Provide useful structures for people interested in fishing. Not too expensive. Can be obtrusive and unattractive to look at. Very expensive and has high maintenance costs. Groynes HARD Rock Armour HARD Piles of large boulders dumped at the foot of a cliff. The rocks force waves to break, absorbing their energy 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 aesthetically pleasing. Often used for fishing. Beach nourishment SOFT Dune regeneration SOFT Relatively cheap and easy to maintain. Blends in with existing beach. Increased tourist potential by creating a bigger beach. Maintains a natural environment that is popular with people and wildlife. Relatively cheap. Marsh creation 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. Sand dunes are effective buffers to the sea yet they are easily damaged and destroyed, especially by trampling. 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. 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. Managed retreat SOFT Allowing controlled flooding of low -lying coastal areas of cliff collapse in areas where the value of the land is low. A cheap option compared to maintaining expensive sea defences that might be protecting relatively lowvalue land. Creates a much-needed habitat for wildlife. It is a real option if there is a high risk of flooding or cliff collapse and where the land is relatively low value. In interrupting longshore drift, they starve the beaches downdrift, often leading to increased rates of erosion elsewhere. Groynes are unnatural and rock groynes in particular can be unattractive. Rocks are usually from other parts of the coastline or even from abroad. Can be expensive to transport. They do not fit with the local geology. Can be very obtrusive. Needs constant maintenance unless structures are built to retain the beach. Time-consuming to plant the marram grass and fence off areas. People do not always respond well to being prohibited from accessing certain areas. Can be damaged by storms. Land will be lost as it is flooded by sea water. Farmers or landowners will need to be compensated. Causes loss of land and the destruction of certain habitats and biodiversity. 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 succession 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 environmentally – 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 tourismrelated 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 regularly 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 levels, 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. Careful 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 breaching. 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 areas 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 Mappleton. However, down the coast there was no longer any beach so the cliffs were exposed and rates of erosion dramatically 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 Mappleton. However, down the coast there was no longer any beach so the cliffs were exposed and rates of erosion dramatically 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 seafront 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 RIVER DRAINAGE BASIN Watershed: The boundary between Source: Where a two drainage basins river starts. Confluence: The point where two rivers join. Tributary: A smaller river that flows into the main channel. Mouth: The end of a river. 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. RIVER LONG PROFILE Source Middle Mouth Large / Angular Bedrock Eroded bedrock – smoother Eroded bedrock – and smaller smoother and smaller Bedrock eroded into fine Narrow / Shallow channel Flow slowed by friction Channel wider and deeper Less friction so faster flow silt and sand Deep and wide channel Little friction resulting in a fast flow 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 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 slower, material is deposited, as there is more friction. 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. 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. MODEL EXAM ANSWERS Exam Question: Explain the formation of ox-bow lakes (6 marks). Grade A Response 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 narrow piece of land called a neck. The river 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. Due to erosion (abrasion) on the outside and deposition on the inside, meanders migrate over their floodplain. In places they migrate towards each other, forming a meander neck. The neck is eventually eroded creating a faster, straighter route for the river. As little water now flows around the loop, deposition 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. 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 WATER 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 river is measured in cumecs - this stands for cubic metres per second. Precipitation is measured in mm - this stands for millimetres. 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). 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! 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’’ 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. Impermeable (Hard) Rock: Under the soil so the rain cannot soak through Hard Dry Soil: 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 methane) in our atmosphere. These gases ‘trapin’ 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. When the soil is baked hard in summer the rain runs over. Factors that increase the risk of flooding Buildings: Rain cannot Cut down trees: soak through Leaves slow rainfall and tarmac and roots take in water. pavements REMEMBER: 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 PHYSICAL: Things created by nature HUMAN: Things created by people CAUSES Tewkesbury is in Gloucestershire in the South West of England 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 Facts & Figures: -Other areas affected by flooding in July included Warwickshire, Shropshire, Worcestershire, Bedfordshire, Oxfordshire and Berkshire. -Total cost of July floods was £6 billion. -rainfall -saturated -contaminated water -floodplains -burst banks -emergency response -relief aid -water treatment -bowsers -flood defences EFFECTS RESPONSES What were the effects of the flooding? How did the authorities respond? -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 farmers were unable to meet demand from consumers. -increased debate about the wisdom of building on floodplains. -RAF Rescue helicopters scrambled to rescue people 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 householders (relief aid). -Severn Trent Water Company brought 50m litres of bottled water in. Also moved 1300 water bowsers 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. 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% 70% of Bangladesh is less than 1m above sea level Unemployment rate: 35.2% (1996) Percentage of population with access to safe water: 97% PHYSICAL CAUSES OF THE FLOODING HUMAN CAUSES OF THE FLOODING THE EFFECTS OF THE FLOODING Over 57% of the land was destroyed by floodwater THE RESPONSES OF THE FLOODING Bangladesh GNP: $380 PER PERSON Flood Protection Measure Hard Type Strategy Soft Dams River Channel Modification Afforestation Washlands Benefits 1. Discharge regulated – floods prevented; 2. HEP potential; 3. Recreation opportunities. 1. Straightening and deepening the channel allows a large amount of water to flow quickly through the river. 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. Intercepts rainfall; 2. Holds soil in place reducing erosion; 3. Relatively cheap; 4. Creates habitats for wildlife; 5. Recreation opportunities. 1. Floods still occur; 2. Large areas of land needed; 3. Forests need to be carefully managed to maximise effect. 1. Floods still occur; 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 In the UK, the supply and demand for water differs. On average the annual rain in the UK shows that Scotland, the north of England, the west of England and Wales have the largest amount of precipitation on average 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 areas have water surplus. 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.. 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. REVISION FLASHCARDS: WATER ON THE LAND Processes of river erosion Processes of transportation Hydraulic action: force of the water Traction: boulders roll along river bed Abrasion: sand, boulders erode channel Saltation: small pebbles bounced along Attrition: load breaking up smaller pieces Suspension: sand / silt carried in flow Solution: some rocks dissolve in river water Solution: dissolved minerals carried away Valley long and cross profiles Landforms of river erosion Upper course long profile: irregular, steep Mainly found in upper course Lower course: lower, smoother, less steep Waterfalls, gorges, interlocking spurs Upper course cross profile: steep V shape Formed by vertical erosion Lower course: gentle V shape, flat River cutting down towards sea level Formation of waterfall and gorge Landforms of river deposition Alternate outcrops of hard and soft rocks Mainly found in lower course Hard is eroded slowly, soft is eroded fast Levées, flood plains, deltas Soft rocks undercut by water splashback River carries a large load of sediment Waterfall retreats upstream, leaving a gorge Deposited where water flow slowed down Formation of meander and ox-bow lake River discharge Outside bend: strong flow, erosion, cliff Volume of water flowing in a river Inside bend: weak flow, slip-off slope Factors: the weather, rock type, relief Meander size increased by lateral erosion High discharge after heavy, prolonged rain Narrow meander neck broken in a flood Particularly impervious rock, steep slopes Causes of flooding Hard engineering strategies Physical: factors favouring high discharge Structures built to prevent flooding Wet weather before; ground is saturated Dams and reservoirs Snow melts, cool weather, little evaporation Concrete / stone channel sides Human: deforestation, building construction Raising the height of river banks Soft engineering strategies Water supply in the UK Measures to reduce the scale of flooding Water surplus: north and west of UK Plant trees on steep valley sides High precipitation, lower population density Zoning: stop more building on flood plains Water deficit: south and east England Issue flood alerts; prepare e.g. sandbags Lowest precipitation, highest population 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. 2. 3. 4. Using examples, describe some of the hazards of living on a destructive plate margin (4) Foundation Using an example, outline the impact of a major earthquake on people and property in the developing world (9) Higher Describe 2 ways in which buildings in developing countries can be made more resistant to earthquakes (2) 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. 9. 10. 11. Outline the responses made by a country to reduce the risk of future earthquakes. (9 marks HIGHER/6 mark FOUNDATION) Using a diagram describe how volcanoes are formed along destructive plate margins (4 marks) Using an example, Describe the potential impacts of a supervolcanic eruption (6 marks) 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! 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 weather 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 FOUNDATION/9marks HIGHER) 9. Using a diagram explain the formation of a hurricane (5 marks) 10. ‘Hurricanes can cause different effects on countries at different levels of development’. Using examples outline evidence to support this statement (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! 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) 1.
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