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Paper 1 revision 29.5.13 bv

Volcanic eruptions can be monitored and potentially predicted using various methods. Earthquake activity, ground deformation measured by tiltmeters and GPS, changes in magma temperature, and gas emissions are monitored in real-time. Seismometers are also used to analyze earthquake waves. By studying patterns of past eruptions, including the timing of flows and gaps between events, volcanologists aim to improve predictions. However, volcanic eruptions often remain unpredictable.

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Paper 1 revision Yr 9 requests
Hydrological cycle
Hydrograph Baseflow = the normal day to day discharge of the river The result of groundwater seeping into the river channel. The rising limb of the hydrograph = the rapid increase in discharge resulting from rainfall causing surface runoff and then later throughflow The time difference between the peak of the rain event and the peak discharge is known as the lag time or basin lag The falling limb (= recession limb) is when discharge decreases and the river’s level falls. It is mainly throughflow which is making up the river water. Peak discharge occurs when the river reaches its highest level
2010Q5c(i) 3 marks 5c(ii) suggest why the hydrographs are different (4 marks)
Which part of the hydrological cycle is shown here? Where is the soil able to absorb most rainfall? Why?
CAUSES EFFECTS STRATEGIES PHYSICAL HUMAN •v.heavy relief rain •High, steep land – rapid run off •Series – steep v shaped tributary valleys-fast flowing •V. wide flat floodplain •River meanders •Farmland drained •Urbanisation on floodplain •Massive flooding – towns, farmland •Homes •Businesses •Crops •Possessions •Transport •Drinking water •Gas, electricity LOST •Dredging ? Costly, unsightly •Flood walls, embankments ? •Allow farmland to flood ? •Objections – farmers, too costly •Temporary aluminium planks ?
What causes flooding? Impermeable rock deforestation Arable farming Building on floodplains Heavy rainfall Lots of tributaries Marshy areas Very wet soil Hard dry soil steep slopes
Physical causes of floods Cause .... Because..... So.... In steep valleys Water runs down steep slopes quickly because water flow faster on steeper slopes Increases discharge quickly which causes flood Heavy rain falling over a long period of time Soil becomes saturated Water table rises, no more rain can infiltrate, causes more run off to rivers which fill and overflow their banks Heavy rain falling over a short period of time If intense rain falls on hard, baked ground then water flows quickly to rivers Causes flash floods as river levels rise rapidly Snow melt in spring Lots of water going into river in short time Increases discharge is too much for it to hold Impermeable rocks Water cannot percolate through the rocks Soils quickly become saturated and this increases overland flow
Human causes of floods .... Cause .... Because .... So.... Urban area Tarmac and concrete is impermeable Increases surface run off so more water flows into the river Deforestation If trees are removed there is nothing to break the rain hitting the ground which may cause soil erosion Eroded soil is washed into channel causing flooding
Flood protection *Dams hold back flood waters *reservoirs store floodwater *straighten channels Increases speed of flow *Dredging Makes channel deeper so can hold more water *levees and embankments Prevents river from overflowing *land use zoning Restricts development to uses unaffected by flooding *afforestation Increases interception etc, reduces run off
Study Figure 9, which shows a plan for flood plain zoning Flood plain zoning is a ‘soft management strategy’. What does this mean? (1mark) Using Figure 9, describe the flood plain zoning and explain why strategies such as this are sustainable. (6marks) AQA A 2005
Strategy How does it work? Advantages disadvantages Dams hold back flood waters River flow can be controlled Reservoirs used for HEP or leisure Costly unsightly Straightening channel Increases speed of flow Flooding risk passed downstream Build levees Prevents river from overflowing Effectively increases channel capacity before overflowing Can provide walkways, leisure routes Costly unsightly Hard engineering strategies summary
RIVERS •Traction •Saltation •Suspension •Solution •Abrasion •Attrition •Solution •Hydraulic action •Vertical erosion •Weathering valley sides •Interlocking spurs -winding •Hard + soft rock •Plunge pool •Overhang •Gorge •Fast flow •Erosion •River cliff •Deep water •Slow flow •Deposition •Slip off slope •Shallow water •Alluvium •Levees •Oxbow lakes •Flat floor •Gentle sides •Heavy rain •Rapid run off •Steep slopes •Deforestation •Urbanisation •Draining farm land •Dredging •Afforestation •Dams + reservoirs •Straighten channels •Strengthen levees •Diversion channels
With the aid of diagram (s) Explain the formation of waterfalls (6) • Alternating bands of hard and soft rock • Rapids • River erodes the softer, less resistant bands of rock • Hard rock undercut • Soft rock worn away through processes of hydraulic action (force of running water, compresses air in cracks in rock and leads to rock weakening and crumbling) and abrasion (action of running water and it’s load, wearing away at channel sides) • Plunge pool is formed at base of waterfall • Overhang eventually collapses providing more material for river to further deepen plunge pool • Process continues repeating, eventually river erodes further back upstream, leading to the formation of a gorge downstream
Meander bend A B A cross section through a meander CONVEX CONCAVE Slow SPEED OF FLOW Fast Shallow DEPTH Deep Deposition PROCESS Erosion Slip off slope FEATURE River Cliff
2007 Q2 (b) Explain why the meander cross- section has this shape The meander cross section is asymmetrical. The river cliff is formed on the outer bend of the meander. This is where the water is deeper and moves more quickly. Hydraulic action and abrasion wear away at the side of the channel, undercutting the river bank to form a river cliff. The slip-off slope is formed on the inside bend by deposition of alluvium. Because the water is shallow and moving more slowly at this point the river load gets deposited to form a gentle slope.
River features: Ox – bow lakes • With the aid of diagrams, explain the formation of an oxbow lake (6 marks) (AQAA04) •Form from a meander •erosion on outside bend especially by hydraulic power •deposition on inside bends where water is shallower and lower velocity •neck narrows, breaks through in time of flood •deposition seals ox bow lake •eventual loss of lake to form meander scar
Formation of a floodplain The floodplain is the wide, flat area of land either side of the river in its lower course. Floodplains contain sediments, often accumulations of sand, gravel, loam, silt, and/or clay. Features of a floodplain include: meanders, ox- bow lakes & levees.
How does a floodplain form? The floodplain is formed by both erosion and deposition. 1. Lateral erosion is caused by meanders and the slow migration downstream to widen the floodplain. 2. The river carries large quantities of suspended load. 3. The deposition on the slip off slopes provides sediment to build up the valley floor. 4. As the water floods onto the floodplain it loses energy, there is greater friction, the water is shallow and the rivers velocity falls so deposition of its suspended load occurs. Regular flooding results in the building up of layers of nutrient rich alluvium which forms a flat and fertile floodplain 5. Over thousands of years the deposits build up to form great thicknesses of alluvium which is why floodplains have fertile soil for farming.
The Physical Causes of the Floods • Most of the country is less than 1 metre above sea level • Snowmelt from the Himalayas • Bangladesh experiences heavy monsoon rains, • Tropical storms (= cyclones) bring heavy rains and coastal flooding • The main cause was the above average & long period of heavy rain which caused all 3 rivers to have their peak flow at the same time!!!
The Human Causes of the Floods 1. Deforestation in Nepal and the Himalayas increases run off and soil erosion which adds to deposition and flooding downstream 2. Urbanisation of the flood plain has increased magnitude & frequency of floods 3. Global warming is blamed for sea level rise, increased snow melt & increased rainfall in the region 4. Poorly maintained embankments (levees) leak & collapse
floods occurred July to Sept July 2004 - 40% Dhaka was under water 60% of country was flooded 600 reported deaths 20 million homeless 100,000 in Dhaka suffered from diarrhoea as floodlwaters left mud and sewage 35cm of rain fell in 1 day on 13th Sept Death toll rose to 750 Airport, roads and railways flooded Bridges destroyed $7billion damage Rice crop destroyed along with food supplies – vegetables Cash crops – jute and sugar Textbook page 115
Short Term Responses • Boats to rescue people • Emergency supplies for food, water, tents and medicines • Fodder for livestock • Repair houses, as well as services such as sewage etc • Aid from other countries Long Term Responses • Reduce deforestation in Nepal & Himalayas • Build 7 large dams in Bangladesh to store excess water $30-$40 million and 40 yrs to complete • Build 5000 flood shelters to accommodate all the population • Build 350km of embankment - 7 metres high at a cost of $6 billion to reduce flooding along the main river channels • Create flood water storage areas • Develop an effective Flood Warning Scheme
2006 Q 7c Kielder Case study • Many urban areas get their water from upland reservoirs. • Using an example of an upland reservoir that you have studied, explain the physical and human advantages of its location. Detailed elaborated or linked statements with precise reference to case study exemplar. Must cover both physical and human advantages of the location. Kielder Water is in the relatively narrow valley of the River North Tyne so the (linked statement) size and cost of building the dam was relatively small (physical). The local geology is shale, which is impermeable so the (linked statement) water does not drain away. (physical) The high rainfall of over 1000mm meant that there (linked statement) was an ample supply of water.(physical) The area was sparsely populated so when (linked statement) the valley was flooded there was not too much disruption to the local population.(human) The water could be used in the densely populated industrial areas of North East England which are near by.(human) The population of the north east could also use the reservoir for leisure pursuits such as fishing(human). (6 marks)
Recap – what is the driving mechanism for plate movement?
Two distinct types of crust Continental Crust Characteristic Oceanic Crust 35-50 km Thickness 5-12 km Granite (light) Composition Basalt (dark) to 3.8 billion B.P. Geological age to 150,000,000 B.P. 2.7 Density 3.0 Ave. +1,000 m Elevation Ave. - 3,000 m No Remelted and destroyed Yes Yes Deformed No 33% Current distribution 67% Rate of Plate Movement San Andreas Fault - 5.5 cm/yr Mid-Atlantic Ridge: Iceland - 1.8 cm/yr; South Atlantic (Ascension Island) - 3.9 cm/yr East Pacific Rise - off South America Most rapid movement - 17.1 cm/yr
Type of boundary Processes Feature example Constructive margins Spreading Divergent Two plates move apart from each other, new oceanic crust is formed Mid ocean ridges, volcanic activity Mid Atlantic ridge Destructive margin Subduction zone The oceanic crust moves towards the continental crust and sinks beneath it due to its greater density. Deep sea trenches and island arcs are formed Volcanic activity Nazca plate sinks under the South American plate Collision zone Two continental crusts collide as neither can sink they are folded up into fold mountains Fold mountains Indian plate collided with Eurasian plate to form Himalayas Conservative margins Passive margins Transform plates Two plates move sideways past each other but land is neither destroyed nor created Fault San Andreas fault California
Supervolcanoes Yellowstone, USA sits on top of a hot spot where light molten magma rises towards and collects in a store beneath the surface. When the store of magma is emptied quickly the land collapses into the emptied chamber and leaves a caldera
How is the distribution of supervolcanoes different from that of volcanoes? 1. Volcanoes occur in linear belt unlike supervolcanoes which are more scattered and occur individually. 2. Volcanoes can occur at destructive, constructive margins and hot spots unlike supervolcanoes which can only be found along destructive boundaries and hot spots.
Describe the ways in which a supervolcano is different from a volcano (Sp paper) Shape – supervolcanoes are flat and surrounded by higher mountains unlike volcanoes which are cone shaped, either gentle or steep. Supervolcanoes form a caldera whereas volcanoes have a crater Size – supervolcanoes are much bigger than a volcano Scale of eruption – supervolcanoes are much more violent and emit far more material than a volcano. Impact – a volcano will affect the local area whilst a supervolcano has a global effect
2011 Describe the likely worldwide effects of a supervolcano eruption. Effects likely to refer to impact in immediate area of an eruption – many deaths(87000 predicted), large ash cloud rising 40 – 50km into atmosphere, destruction of10000 square km of land, ash 15cm think covering buildings within 10000km, flights suspended, livestock and farmland affected. The UK would see the arrival of the as h5 days after the eruption; temperatures would fall between 12 and 15 degrees. Parts of Europe and America and Asia would see constant snow cover for 3 years, cropswould fail, monsoon rains would fail, 40% of population could face starvation. (6marks) Level 1 Basic (1-4 marks) Describes effects of a supervolcano eruption. Statements are general in a random order. Lots of people will die. There will be huge amounts of ash. People will choke to death. Buildings will collapse. Crops and animals will die. People will starve. In Yellowstone, there would be no planes. Level 2 Clear (5-6 marks) Effects are clearly described, in an organised way. There is clear reference to global aspect. Statements are linked. One in three people will be killed within 1000km of an eruption. Buildings would collapse within this area due to the weight of the ash. This would ground planes and make road transport difficult. Livestock would die as they would choke in hot ash. UK (England) would see the arrival of the ash about 5 days later. This will circle the Earth, changing the climate. Temperatures will fall by 10 degrees and this will make it difficult to grow food in many areas. Certain parts of northern Europe will be snow covered for 3 years, so no food will be able to be grown.
SHIELD VOLCANO COMPOSITE VOLCANO Constructive Hot spots Type of plate boundary destructive basic Type of magma acid Runny, fluid Sticky, viscous Gentle, effusive Type of eruption explosive Gentle sides shape Steep sides Wide base Area at base Narrow base Mauna Loa, Hawaii example Mt St Helens, Montserrat
Monitoring and Predicting volcanoes 1. Earthquakes 2. Tiltmeters can identify small changes in slopes 3. Global positioning systems (GPS) use satellites to detect movement of as little as 1mm. 4. Change in temperature of magma can be monitored. 5. Escaping gases from the vent change before an eruption – increase in sulphur dioxide. 6. Seismometers used to measure earthquake waves. 7. Analysis of past eruptions; gap between them and pattern of flows can all help with predictions. However, volcanoes can still be very unpredictable.
Describe the distribution of volcanoes 1. Not found everywhere –largely found in certain linear belts 2. Located on plate boundaries – found on destructive (Pacific Rim) and constructive plate boundaries (Mid Atlantic Ridge) 3. Destructive plate boundary e.g. Mt St Helens, N. America 4. Constructive plate boundary – Heimaey, Iceland, Mid Atlantic Ridge 5. A few volcanoes are located away from plate boundaries e.g. Mauna Loa in Hawaii – hot spots, plumes of magma caused by radio active heat within the mantle
Q1a (ii) Explain why volcanoes are found at destructive plate boundaries (3 marks) At a destructive boundary an oceanic plate and a continental plate are moving towards each other due to convection currents in the mantle The denser oceanic crust is subducted below the lighter continental crust. Pressure is exerted as the plates grind past each other and friction causes the oceanic plate to melt along with sediments. The lighter magma then gets pushed up to the surface via cracks until it erupts.
Volcano case study Primary impacts Secondary impacts Immediate responses Long term responses
Volcano Mt St Helens pg 19 Primary impacts Secondary impacts 57 died Trees uprooted Logging camps destroyed River temperatures raised Sediment and mud choked channel Loss of wildlife Farming crops ruined Death of fish in rivers Flood waters washed away road and railway bridges car engines affected by ash Electricity supplies interrupted Telephone wires cut Planes grounded
Volcano Mt St Helens pg 19 Immediate responses Long term responses Mobilised helicopters to search for survivors Finding shelter for stranded tourists Emergency medical treatment Providing citizens with face masks Clearing ash from roads to allow traffic to flow Buildings and bridges need rebuilding Drainage needed to be monitored to ensure no flooding occurred as a result of debris Forest needed replanting
Formation of fold mountains Destructive boundary (subduction = oceanic crust meets continental crust) 1. Sediment brought down by rivers collects in a geosyncline, which is a depression under the sea; this is often near a subduction zone, along a destructive plate margin. 2. As more sediment collects on top, the sediment is compressed and turns into rock. 3. Plate movement, caused by convection currents in the mantle, causes compression of the rocks, which leads to folding, which causes fold mountains. Eg. Rockies, Collision boundary (continental crust meets continental crust) • Himalayas (which are formed along a collision zone).
How do people adapt to fold mtns Farming: Valley floors – flat, deep fertile soils, sheltered Transhumance – seasonal movement of cattle up mountainside allowing hay and fodder to be grown on valley floor Milk butter cheese Plastic tubes carry milk down mountainside New roads, quad bikes and cable cars give easier access to upland pastures Farms are on south facing sides which is warmer Crops: hay, cereals, sugar been, vines and fruits
tourism • Chamonix – skiing • Important industry • Vast amounts of money spent on roads, railways tunnels avalanche shelters cable cars houses and restaurants • Tourist facilities benefit locals as well as providing jobs • Skiers, climbers, walkers, scenery • Glaciated mountains, snow capped peaks and forests • Lakes • Winter sports resorts • Alps – close to affluent parts of Europe • Alpine climate has good snowfall, crisp clear days for winter sports and warm summers
HEP Steep slopes, high perecipitation and summer melting of glaciers produce fast flowing rivers that are ideal for generating HEP Narrow valleys are easy to dam Lakes in which to store water Electricity an be used by industries that use large amounts of electricity – saw mills, electro chemicals, aluminium smelting
forestry • Trees grow up to 1800m • Timber industry • Soft wood felled and used as fuel, for building and in the manufacture of wood pulp and paper • Switzerland – craft industries – wood carving, cuckoo clocks
problems • High altitude and steep slopes mean it is hard to build houses, industries and communications • Roads and railways need expensive tunnels, passes, shelters and bends • Little flat land for farming, hard to use machinery • Cold wet climate – short growing season • Avalanches and rockfalls block roads • Need avalanche protection
Legacy 2005
Any 3 facts from Figure 1 e.g. earthquakes occur in linear clusters (1), many occur on plate boundaries (1) especially destructive and/or conservative plate boundaries(1); with example (1). Clustering around edge of Pacific plate (1). Maximum 1 for negative
Precautions against earthquakes Individuals Authorities Long term planning Emergency pack – water, food, blankets, first aid kit, radio and torch Monitor hazard so people can be warned Ensure road and railways are built to reduce effects of earthquakes Shelter under table or bed Have emergency supplies ready Ensure new buildings are earthquake proof Turn off gas and electricity Make plans for shelter, food and water supplies and for emergency services Provide education and advertising so people know what to do. After earthquake – move to open ground Plan to broadcast information for people affected
1. Computer controlled movable roof weights to counter the shock waves 2. Steel frames that can sway during earth movements. Building needs to be stiff vertically but flexible horizontally 3. ‘Birdcage’ interlocking steel frame, cross bracing to give added strength and prevent twisting 4. Automatic window shutters to prevent falling glass 5. Sheer core of reinforced concrete and tensioned cables around lift shaft 6. Fire resistant building materials 7. Outer panels flexibly attached to steel structure 8. Automatic sprinkler system and gas shut off to prevent fires 9. Strengthened steel and reinforced concrete road supports 10. Foundations set deep into the ground 11. Rubber shock absorbers to absorb earth tremors, foundation piles made out of alternative layers of steel and rubber to make building flexible 12. Open areas where people can assemble if evacuated
Impact of earthquake • Depends on magnitude of earthquake and density of the population in an area • Wealth - People and authorities in richer areas are generally more prepared than those in poorer areas • Wealth means they are able to develop – Earthquake proof buildings – More effective emergency services – Speedier response
Tsunamis are caused by earthquakes at sea. Earthquakes happen when the plates that make up the Earth's surface suddenly move against each other. A tsunami forms when energy from an earthquake vertically jolts the seabed by several metres, displacing hundreds of cubic kilometres of water. Large waves begin moving through the ocean, away from the earthquake's epicentre. In deep water, the tsunami moves at great speeds. When it reaches shallow water near coastal areas, the tsunami slows but increases in height.
Cause Effect Response 9.1 Richter Scale earthquake caused by the subduction of the Indo-Australian plate beneath the Eurasian plate. The sudden movement of the plate under the sea caused the giant wave 5-40 metres high, which first hit Sumatra, then Sri Lanka and Thailand. Primary effects •>220,000 people died •650,000 seriously injured •2 million homeless •Many buildings were swept away by the waves as they were made of wood •Roads, bridges and utilities destroyed Secondary effects •Spread of diseases such as cholera, dysentery •Loss of coastal fishing industries •Loss of tourism revenue from areas such as Thailand •Many orphans left due to children surviving without parents Immediate response: •Panic in the first instance; scale of disaster meant rescue services and could not cope. •Injured people were untreated for days. •Bodies left to rot in streets. •Immediate response from international aid agencies and governments, providing US$7billion. •160 aid organisations and UN agencies helped to provide food, shelter and medical help •Provided water purification tablets, food, sheeting and tents. Longer term response •Governments struggled to spend all of money donated, but progress made. •Banda Aceh in Sumatra rebuilt, although still 60,000 Indonesians still living in tents. •Indian Ocean Tsunami Warning system was set up June 2006 to try and give warning of tsunamis with 39 tsunami buoys •289 hospitals been rebuilt or rehabilitated
Weathering and erosion work together. Weathering breaks up and weakens the surface of rocks but leaves debris in situ Erosion wears away and removes the loosened material.
Mass movement: movement of material downhill due to the force of gravity. Can be very slow eg soil creep, or fast eg mud-slide or rock fall or rotational slip causing slumping. Mass movement is increased if there is presence of water to lubricate; also if there is no vegetation holding slope in place.
Mass movement - slump
Why are soft coastlines vulnerable to rapid erosion? •Many parts of the UK have coastlines of softer rocks such as clay which is very susceptible to erosion and weathering. •These rocks do not have a strong structure and become unstable when wet •A combination of heavy rainfall soaking through the rock and wave attack at the base of the cliff may trigger slumping and landslides
June 2010 Mass movement is a process affecting the coastal zone. Describe this process. (3 marks) Mass movement occurs when loose material on the land surface (1) moves downslope (1) due to gravity (1) sliding and slumping (1). This is often fast and sudden (1) as with landslides (1) when the base of the cliff has been eroded, making the cliff unstable (1). With a landslide, the whole column of material moves in one go (1), slumping is similar, but this involves a curved movement (1).
Paper 1 revision 29.5.13 bv

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Paper 1 revision 29.5.13 bv

  • 1.
  • 2.
  • 4.
    Hydrograph Baseflow = thenormal day to day discharge of the river The result of groundwater seeping into the river channel. The rising limb of the hydrograph = the rapid increase in discharge resulting from rainfall causing surface runoff and then later throughflow The time difference between the peak of the rain event and the peak discharge is known as the lag time or basin lag The falling limb (= recession limb) is when discharge decreases and the river’s level falls. It is mainly throughflow which is making up the river water. Peak discharge occurs when the river reaches its highest level
  • 5.
    2010Q5c(i) 3 marks 5c(ii)suggest why the hydrographs are different (4 marks)
  • 6.
    Which part ofthe hydrological cycle is shown here? Where is the soil able to absorb most rainfall? Why?
  • 7.
    CAUSES EFFECTS STRATEGIES PHYSICALHUMAN •v.heavy relief rain •High, steep land – rapid run off •Series – steep v shaped tributary valleys-fast flowing •V. wide flat floodplain •River meanders •Farmland drained •Urbanisation on floodplain •Massive flooding – towns, farmland •Homes •Businesses •Crops •Possessions •Transport •Drinking water •Gas, electricity LOST •Dredging ? Costly, unsightly •Flood walls, embankments ? •Allow farmland to flood ? •Objections – farmers, too costly •Temporary aluminium planks ?
  • 8.
    What causes flooding? Impermeablerock deforestation Arable farming Building on floodplains Heavy rainfall Lots of tributaries Marshy areas Very wet soil Hard dry soil steep slopes
  • 9.
    Physical causes of floods Cause.... Because..... So.... In steep valleys Water runs down steep slopes quickly because water flow faster on steeper slopes Increases discharge quickly which causes flood Heavy rain falling over a long period of time Soil becomes saturated Water table rises, no more rain can infiltrate, causes more run off to rivers which fill and overflow their banks Heavy rain falling over a short period of time If intense rain falls on hard, baked ground then water flows quickly to rivers Causes flash floods as river levels rise rapidly Snow melt in spring Lots of water going into river in short time Increases discharge is too much for it to hold Impermeable rocks Water cannot percolate through the rocks Soils quickly become saturated and this increases overland flow
  • 10.
    Human causes offloods .... Cause .... Because .... So.... Urban area Tarmac and concrete is impermeable Increases surface run off so more water flows into the river Deforestation If trees are removed there is nothing to break the rain hitting the ground which may cause soil erosion Eroded soil is washed into channel causing flooding
  • 11.
    Flood protection *Dams hold backflood waters *reservoirs store floodwater *straighten channels Increases speed of flow *Dredging Makes channel deeper so can hold more water *levees and embankments Prevents river from overflowing *land use zoning Restricts development to uses unaffected by flooding *afforestation Increases interception etc, reduces run off
  • 12.
    Study Figure 9,which shows a plan for flood plain zoning Flood plain zoning is a ‘soft management strategy’. What does this mean? (1mark) Using Figure 9, describe the flood plain zoning and explain why strategies such as this are sustainable. (6marks) AQA A 2005
  • 13.
    Strategy How doesit work? Advantages disadvantages Dams hold back flood waters River flow can be controlled Reservoirs used for HEP or leisure Costly unsightly Straightening channel Increases speed of flow Flooding risk passed downstream Build levees Prevents river from overflowing Effectively increases channel capacity before overflowing Can provide walkways, leisure routes Costly unsightly Hard engineering strategies summary
  • 14.
    RIVERS •Traction •Saltation •Suspension •Solution •Abrasion •Attrition •Solution •Hydraulic action •Vertical erosion •Weathering valleysides •Interlocking spurs -winding •Hard + soft rock •Plunge pool •Overhang •Gorge •Fast flow •Erosion •River cliff •Deep water •Slow flow •Deposition •Slip off slope •Shallow water •Alluvium •Levees •Oxbow lakes •Flat floor •Gentle sides •Heavy rain •Rapid run off •Steep slopes •Deforestation •Urbanisation •Draining farm land •Dredging •Afforestation •Dams + reservoirs •Straighten channels •Strengthen levees •Diversion channels
  • 15.
    With the aidof diagram (s) Explain the formation of waterfalls (6) • Alternating bands of hard and soft rock • Rapids • River erodes the softer, less resistant bands of rock • Hard rock undercut • Soft rock worn away through processes of hydraulic action (force of running water, compresses air in cracks in rock and leads to rock weakening and crumbling) and abrasion (action of running water and it’s load, wearing away at channel sides) • Plunge pool is formed at base of waterfall • Overhang eventually collapses providing more material for river to further deepen plunge pool • Process continues repeating, eventually river erodes further back upstream, leading to the formation of a gorge downstream
  • 17.
    Meander bend A B Across section through a meander CONVEX CONCAVE Slow SPEED OF FLOW Fast Shallow DEPTH Deep Deposition PROCESS Erosion Slip off slope FEATURE River Cliff
  • 18.
    2007 Q2 (b)Explain why the meander cross- section has this shape The meander cross section is asymmetrical. The river cliff is formed on the outer bend of the meander. This is where the water is deeper and moves more quickly. Hydraulic action and abrasion wear away at the side of the channel, undercutting the river bank to form a river cliff. The slip-off slope is formed on the inside bend by deposition of alluvium. Because the water is shallow and moving more slowly at this point the river load gets deposited to form a gentle slope.
  • 20.
    River features: Ox– bow lakes • With the aid of diagrams, explain the formation of an oxbow lake (6 marks) (AQAA04) •Form from a meander •erosion on outside bend especially by hydraulic power •deposition on inside bends where water is shallower and lower velocity •neck narrows, breaks through in time of flood •deposition seals ox bow lake •eventual loss of lake to form meander scar
  • 21.
    Formation of afloodplain The floodplain is the wide, flat area of land either side of the river in its lower course. Floodplains contain sediments, often accumulations of sand, gravel, loam, silt, and/or clay. Features of a floodplain include: meanders, ox- bow lakes & levees.
  • 22.
    How does afloodplain form? The floodplain is formed by both erosion and deposition. 1. Lateral erosion is caused by meanders and the slow migration downstream to widen the floodplain. 2. The river carries large quantities of suspended load. 3. The deposition on the slip off slopes provides sediment to build up the valley floor. 4. As the water floods onto the floodplain it loses energy, there is greater friction, the water is shallow and the rivers velocity falls so deposition of its suspended load occurs. Regular flooding results in the building up of layers of nutrient rich alluvium which forms a flat and fertile floodplain 5. Over thousands of years the deposits build up to form great thicknesses of alluvium which is why floodplains have fertile soil for farming.
  • 23.
    The Physical Causesof the Floods • Most of the country is less than 1 metre above sea level • Snowmelt from the Himalayas • Bangladesh experiences heavy monsoon rains, • Tropical storms (= cyclones) bring heavy rains and coastal flooding • The main cause was the above average & long period of heavy rain which caused all 3 rivers to have their peak flow at the same time!!!
  • 24.
    The Human Causesof the Floods 1. Deforestation in Nepal and the Himalayas increases run off and soil erosion which adds to deposition and flooding downstream 2. Urbanisation of the flood plain has increased magnitude & frequency of floods 3. Global warming is blamed for sea level rise, increased snow melt & increased rainfall in the region 4. Poorly maintained embankments (levees) leak & collapse
  • 25.
    floods occurred Julyto Sept July 2004 - 40% Dhaka was under water 60% of country was flooded 600 reported deaths 20 million homeless 100,000 in Dhaka suffered from diarrhoea as floodlwaters left mud and sewage 35cm of rain fell in 1 day on 13th Sept Death toll rose to 750 Airport, roads and railways flooded Bridges destroyed $7billion damage Rice crop destroyed along with food supplies – vegetables Cash crops – jute and sugar Textbook page 115
  • 26.
    Short Term Responses •Boats to rescue people • Emergency supplies for food, water, tents and medicines • Fodder for livestock • Repair houses, as well as services such as sewage etc • Aid from other countries Long Term Responses • Reduce deforestation in Nepal & Himalayas • Build 7 large dams in Bangladesh to store excess water $30-$40 million and 40 yrs to complete • Build 5000 flood shelters to accommodate all the population • Build 350km of embankment - 7 metres high at a cost of $6 billion to reduce flooding along the main river channels • Create flood water storage areas • Develop an effective Flood Warning Scheme
  • 27.
    2006 Q 7cKielder Case study • Many urban areas get their water from upland reservoirs. • Using an example of an upland reservoir that you have studied, explain the physical and human advantages of its location. Detailed elaborated or linked statements with precise reference to case study exemplar. Must cover both physical and human advantages of the location. Kielder Water is in the relatively narrow valley of the River North Tyne so the (linked statement) size and cost of building the dam was relatively small (physical). The local geology is shale, which is impermeable so the (linked statement) water does not drain away. (physical) The high rainfall of over 1000mm meant that there (linked statement) was an ample supply of water.(physical) The area was sparsely populated so when (linked statement) the valley was flooded there was not too much disruption to the local population.(human) The water could be used in the densely populated industrial areas of North East England which are near by.(human) The population of the north east could also use the reservoir for leisure pursuits such as fishing(human). (6 marks)
  • 29.
    Recap – whatis the driving mechanism for plate movement?
  • 30.
    Two distinct typesof crust Continental Crust Characteristic Oceanic Crust 35-50 km Thickness 5-12 km Granite (light) Composition Basalt (dark) to 3.8 billion B.P. Geological age to 150,000,000 B.P. 2.7 Density 3.0 Ave. +1,000 m Elevation Ave. - 3,000 m No Remelted and destroyed Yes Yes Deformed No 33% Current distribution 67% Rate of Plate Movement San Andreas Fault - 5.5 cm/yr Mid-Atlantic Ridge: Iceland - 1.8 cm/yr; South Atlantic (Ascension Island) - 3.9 cm/yr East Pacific Rise - off South America Most rapid movement - 17.1 cm/yr
  • 31.
    Type of boundaryProcesses Feature example Constructive margins Spreading Divergent Two plates move apart from each other, new oceanic crust is formed Mid ocean ridges, volcanic activity Mid Atlantic ridge Destructive margin Subduction zone The oceanic crust moves towards the continental crust and sinks beneath it due to its greater density. Deep sea trenches and island arcs are formed Volcanic activity Nazca plate sinks under the South American plate Collision zone Two continental crusts collide as neither can sink they are folded up into fold mountains Fold mountains Indian plate collided with Eurasian plate to form Himalayas Conservative margins Passive margins Transform plates Two plates move sideways past each other but land is neither destroyed nor created Fault San Andreas fault California
  • 32.
    Supervolcanoes Yellowstone, USA sitson top of a hot spot where light molten magma rises towards and collects in a store beneath the surface. When the store of magma is emptied quickly the land collapses into the emptied chamber and leaves a caldera
  • 34.
    How is thedistribution of supervolcanoes different from that of volcanoes? 1. Volcanoes occur in linear belt unlike supervolcanoes which are more scattered and occur individually. 2. Volcanoes can occur at destructive, constructive margins and hot spots unlike supervolcanoes which can only be found along destructive boundaries and hot spots.
  • 35.
    Describe the waysin which a supervolcano is different from a volcano (Sp paper) Shape – supervolcanoes are flat and surrounded by higher mountains unlike volcanoes which are cone shaped, either gentle or steep. Supervolcanoes form a caldera whereas volcanoes have a crater Size – supervolcanoes are much bigger than a volcano Scale of eruption – supervolcanoes are much more violent and emit far more material than a volcano. Impact – a volcano will affect the local area whilst a supervolcano has a global effect
  • 36.
    2011 Describe thelikely worldwide effects of a supervolcano eruption. Effects likely to refer to impact in immediate area of an eruption – many deaths(87000 predicted), large ash cloud rising 40 – 50km into atmosphere, destruction of10000 square km of land, ash 15cm think covering buildings within 10000km, flights suspended, livestock and farmland affected. The UK would see the arrival of the as h5 days after the eruption; temperatures would fall between 12 and 15 degrees. Parts of Europe and America and Asia would see constant snow cover for 3 years, cropswould fail, monsoon rains would fail, 40% of population could face starvation. (6marks) Level 1 Basic (1-4 marks) Describes effects of a supervolcano eruption. Statements are general in a random order. Lots of people will die. There will be huge amounts of ash. People will choke to death. Buildings will collapse. Crops and animals will die. People will starve. In Yellowstone, there would be no planes. Level 2 Clear (5-6 marks) Effects are clearly described, in an organised way. There is clear reference to global aspect. Statements are linked. One in three people will be killed within 1000km of an eruption. Buildings would collapse within this area due to the weight of the ash. This would ground planes and make road transport difficult. Livestock would die as they would choke in hot ash. UK (England) would see the arrival of the ash about 5 days later. This will circle the Earth, changing the climate. Temperatures will fall by 10 degrees and this will make it difficult to grow food in many areas. Certain parts of northern Europe will be snow covered for 3 years, so no food will be able to be grown.
  • 37.
    SHIELD VOLCANO COMPOSITE VOLCANO Constructive Hotspots Type of plate boundary destructive basic Type of magma acid Runny, fluid Sticky, viscous Gentle, effusive Type of eruption explosive Gentle sides shape Steep sides Wide base Area at base Narrow base Mauna Loa, Hawaii example Mt St Helens, Montserrat
  • 38.
    Monitoring and Predictingvolcanoes 1. Earthquakes 2. Tiltmeters can identify small changes in slopes 3. Global positioning systems (GPS) use satellites to detect movement of as little as 1mm. 4. Change in temperature of magma can be monitored. 5. Escaping gases from the vent change before an eruption – increase in sulphur dioxide. 6. Seismometers used to measure earthquake waves. 7. Analysis of past eruptions; gap between them and pattern of flows can all help with predictions. However, volcanoes can still be very unpredictable.
  • 39.
    Describe the distributionof volcanoes 1. Not found everywhere –largely found in certain linear belts 2. Located on plate boundaries – found on destructive (Pacific Rim) and constructive plate boundaries (Mid Atlantic Ridge) 3. Destructive plate boundary e.g. Mt St Helens, N. America 4. Constructive plate boundary – Heimaey, Iceland, Mid Atlantic Ridge 5. A few volcanoes are located away from plate boundaries e.g. Mauna Loa in Hawaii – hot spots, plumes of magma caused by radio active heat within the mantle
  • 40.
    Q1a (ii) Explainwhy volcanoes are found at destructive plate boundaries (3 marks) At a destructive boundary an oceanic plate and a continental plate are moving towards each other due to convection currents in the mantle The denser oceanic crust is subducted below the lighter continental crust. Pressure is exerted as the plates grind past each other and friction causes the oceanic plate to melt along with sediments. The lighter magma then gets pushed up to the surface via cracks until it erupts.
  • 41.
    Volcano case study Primaryimpacts Secondary impacts Immediate responses Long term responses
  • 42.
    Volcano Mt StHelens pg 19 Primary impacts Secondary impacts 57 died Trees uprooted Logging camps destroyed River temperatures raised Sediment and mud choked channel Loss of wildlife Farming crops ruined Death of fish in rivers Flood waters washed away road and railway bridges car engines affected by ash Electricity supplies interrupted Telephone wires cut Planes grounded
  • 43.
    Volcano Mt StHelens pg 19 Immediate responses Long term responses Mobilised helicopters to search for survivors Finding shelter for stranded tourists Emergency medical treatment Providing citizens with face masks Clearing ash from roads to allow traffic to flow Buildings and bridges need rebuilding Drainage needed to be monitored to ensure no flooding occurred as a result of debris Forest needed replanting
  • 44.
    Formation of foldmountains Destructive boundary (subduction = oceanic crust meets continental crust) 1. Sediment brought down by rivers collects in a geosyncline, which is a depression under the sea; this is often near a subduction zone, along a destructive plate margin. 2. As more sediment collects on top, the sediment is compressed and turns into rock. 3. Plate movement, caused by convection currents in the mantle, causes compression of the rocks, which leads to folding, which causes fold mountains. Eg. Rockies, Collision boundary (continental crust meets continental crust) • Himalayas (which are formed along a collision zone).
  • 45.
    How do peopleadapt to fold mtns Farming: Valley floors – flat, deep fertile soils, sheltered Transhumance – seasonal movement of cattle up mountainside allowing hay and fodder to be grown on valley floor Milk butter cheese Plastic tubes carry milk down mountainside New roads, quad bikes and cable cars give easier access to upland pastures Farms are on south facing sides which is warmer Crops: hay, cereals, sugar been, vines and fruits
  • 46.
    tourism • Chamonix –skiing • Important industry • Vast amounts of money spent on roads, railways tunnels avalanche shelters cable cars houses and restaurants • Tourist facilities benefit locals as well as providing jobs • Skiers, climbers, walkers, scenery • Glaciated mountains, snow capped peaks and forests • Lakes • Winter sports resorts • Alps – close to affluent parts of Europe • Alpine climate has good snowfall, crisp clear days for winter sports and warm summers
  • 47.
    HEP Steep slopes, highperecipitation and summer melting of glaciers produce fast flowing rivers that are ideal for generating HEP Narrow valleys are easy to dam Lakes in which to store water Electricity an be used by industries that use large amounts of electricity – saw mills, electro chemicals, aluminium smelting
  • 48.
    forestry • Trees growup to 1800m • Timber industry • Soft wood felled and used as fuel, for building and in the manufacture of wood pulp and paper • Switzerland – craft industries – wood carving, cuckoo clocks
  • 49.
    problems • High altitudeand steep slopes mean it is hard to build houses, industries and communications • Roads and railways need expensive tunnels, passes, shelters and bends • Little flat land for farming, hard to use machinery • Cold wet climate – short growing season • Avalanches and rockfalls block roads • Need avalanche protection
  • 50.
  • 51.
    Any 3 factsfrom Figure 1 e.g. earthquakes occur in linear clusters (1), many occur on plate boundaries (1) especially destructive and/or conservative plate boundaries(1); with example (1). Clustering around edge of Pacific plate (1). Maximum 1 for negative
  • 53.
    Precautions against earthquakes IndividualsAuthorities Long term planning Emergency pack – water, food, blankets, first aid kit, radio and torch Monitor hazard so people can be warned Ensure road and railways are built to reduce effects of earthquakes Shelter under table or bed Have emergency supplies ready Ensure new buildings are earthquake proof Turn off gas and electricity Make plans for shelter, food and water supplies and for emergency services Provide education and advertising so people know what to do. After earthquake – move to open ground Plan to broadcast information for people affected
  • 54.
    1. Computer controlledmovable roof weights to counter the shock waves 2. Steel frames that can sway during earth movements. Building needs to be stiff vertically but flexible horizontally 3. ‘Birdcage’ interlocking steel frame, cross bracing to give added strength and prevent twisting 4. Automatic window shutters to prevent falling glass 5. Sheer core of reinforced concrete and tensioned cables around lift shaft 6. Fire resistant building materials 7. Outer panels flexibly attached to steel structure 8. Automatic sprinkler system and gas shut off to prevent fires 9. Strengthened steel and reinforced concrete road supports 10. Foundations set deep into the ground 11. Rubber shock absorbers to absorb earth tremors, foundation piles made out of alternative layers of steel and rubber to make building flexible 12. Open areas where people can assemble if evacuated
  • 55.
    Impact of earthquake •Depends on magnitude of earthquake and density of the population in an area • Wealth - People and authorities in richer areas are generally more prepared than those in poorer areas • Wealth means they are able to develop – Earthquake proof buildings – More effective emergency services – Speedier response
  • 57.
    Tsunamis are causedby earthquakes at sea. Earthquakes happen when the plates that make up the Earth's surface suddenly move against each other. A tsunami forms when energy from an earthquake vertically jolts the seabed by several metres, displacing hundreds of cubic kilometres of water. Large waves begin moving through the ocean, away from the earthquake's epicentre. In deep water, the tsunami moves at great speeds. When it reaches shallow water near coastal areas, the tsunami slows but increases in height.
  • 58.
    Cause Effect Response 9.1Richter Scale earthquake caused by the subduction of the Indo-Australian plate beneath the Eurasian plate. The sudden movement of the plate under the sea caused the giant wave 5-40 metres high, which first hit Sumatra, then Sri Lanka and Thailand. Primary effects •>220,000 people died •650,000 seriously injured •2 million homeless •Many buildings were swept away by the waves as they were made of wood •Roads, bridges and utilities destroyed Secondary effects •Spread of diseases such as cholera, dysentery •Loss of coastal fishing industries •Loss of tourism revenue from areas such as Thailand •Many orphans left due to children surviving without parents Immediate response: •Panic in the first instance; scale of disaster meant rescue services and could not cope. •Injured people were untreated for days. •Bodies left to rot in streets. •Immediate response from international aid agencies and governments, providing US$7billion. •160 aid organisations and UN agencies helped to provide food, shelter and medical help •Provided water purification tablets, food, sheeting and tents. Longer term response •Governments struggled to spend all of money donated, but progress made. •Banda Aceh in Sumatra rebuilt, although still 60,000 Indonesians still living in tents. •Indian Ocean Tsunami Warning system was set up June 2006 to try and give warning of tsunamis with 39 tsunami buoys •289 hospitals been rebuilt or rehabilitated
  • 59.
    Weathering and erosionwork together. Weathering breaks up and weakens the surface of rocks but leaves debris in situ Erosion wears away and removes the loosened material.
  • 60.
    Mass movement: movementof material downhill due to the force of gravity. Can be very slow eg soil creep, or fast eg mud-slide or rock fall or rotational slip causing slumping. Mass movement is increased if there is presence of water to lubricate; also if there is no vegetation holding slope in place.
  • 61.
  • 62.
    Why are softcoastlines vulnerable to rapid erosion? •Many parts of the UK have coastlines of softer rocks such as clay which is very susceptible to erosion and weathering. •These rocks do not have a strong structure and become unstable when wet •A combination of heavy rainfall soaking through the rock and wave attack at the base of the cliff may trigger slumping and landslides
  • 63.
    June 2010 Mass movementis a process affecting the coastal zone. Describe this process. (3 marks) Mass movement occurs when loose material on the land surface (1) moves downslope (1) due to gravity (1) sliding and slumping (1). This is often fast and sudden (1) as with landslides (1) when the base of the cliff has been eroded, making the cliff unstable (1). With a landslide, the whole column of material moves in one go (1), slumping is similar, but this involves a curved movement (1).