Upper Sec Elective Geography - Coasts
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Upper Sec Elective Geography - Coasts

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  • During WWII, the Japanese sought to capture Singapore to use its port as a launch pad against other Allied interests in the area, and to consolidate the invaded territory.
  • It opened up a second front the Germans had to fight on, relieving pressure on the soviet forces on the eastern front. Until that point the Germans were fighting the Russians in the East and holding the line in Italy. The Italian front didn't tie up very many troops because the terrain favored the German defenders. By attacking into France, the Allies forced the German army to defend itself there as well. This took some pressure off the Russians, and directly resulted in the liberation of France and the low countries.
  • Sound waves
  • Light waves. Black is the absence of color (and is therefore not a color).
  • Heat waves.
  • http://www.youtube.com/watch?v=7nS_aR8XX_U
  • Waves attack lines of weaknesses along the rocky surface
  • Instead of horizontal layers of hard/soft rocks, these are vertical layers.
  • Under normal circumstances, when the coastline is straight and even, as waves approach the shore, its energy is being dispersed evenly throughout the coastline.
  • In the presence of headlands and bays however, the opposite occurs. Energy becomes concentrated along the headlands.
  • Waves will bend and contour to follow the shape of the coast. Areas protruding outwards (headlands) will thus be exposed to more destructive waves while areas at the back are protected and receive more constructive waves.
  • Hence why beaches tend to be found in bays and cliff/shore platforms tend to be found along headlands.
  • The surrounding cliffs and hills are rich in iron, and is why the beach's sand is such a deep red.
  • Black sand is actually broken down lava. Such beaches are only found near volconoes.

Transcript

  • 1. CoastsEye for Geography, Pg. 86
  • 2. By the end of the chapterYou should all be able to DIEE1. Describe what is a coast.2. Identify landforms/features of a coast.3. Explain how those landforms are formed.4. Evaluate the measures taken to protect coastal environments
  • 3. What is a coast?
  • 4. Is this a coast?
  • 5. Is this a coast?
  • 6. Is this a coast?
  • 7. Is this a coast?
  • 8. They are all coasts!
  • 9. What is a coast?The zone where the sea orocean meets the landA precise line that can becalled a coastline cannot bedetermined due to thedynamic nature of tides.
  • 10. Coast vs. beachA beach is a coastal landform.Can also be found in lakes or rivers!
  • 11. WHY ARE COASTSIMPORTANT?
  • 12. Importance to humans Many of the worlds major cities were founded along coasts  WHY? Historically, coasts were a crucial battleground during times of war.
  • 13. The Battle of Sarimbun Beach was thefirst stage of the Japanese assault onSingapore during WWII
  • 14. The Battle of Normandy: It was the largest amphibiousassault ever taken place in human history. Helped changethe course of WWII to the Allies favour.
  • 15. Importance to humans Many of the worlds major cities were founded along coasts  ports facilitated trade Historically, coasts were a crucial battleground during war. Coasts, especially those with beaches are an important draw for tourists.
  • 16. In many island nations such asthose of the Mediterranean, SouthPacific and Caribbean, tourism iscentral to the economy.
  • 17. Environmental importance Coastal ecosystems are unique and cannot be replicated  mangroves, marshes, coral reefs etc These ecosystems support a wide range of plant and animal species  these can be harnessed for human needs
  • 18. Local economies near major coralreefs and mangroves benefit from anabundance of fish and other marinecreatures as a food source.
  • 19. In medicine, chemical compounds from corals areused as research for AIDS and cancer. Coralskeletons are also used for bone grafting in humans.
  • 20. Coral reefs form natural barriers that protect nearbyshorelines from the eroding forces of the sea, therebyprotecting coastal dwellings, agricultural land.
  • 21. Environmental importance Coastal ecosystems are unique and cannot be replicated  mangroves, marshes, coral reefs etc These ecosystems support a wide range of plant and animal species  these can be harnessed for human needs
  • 22. How are coasts created?
  • 23. WavesEye for Geography, Pg. 88
  • 24. There are many different types of waves
  • 25. FormationResult from wind blowing overa stretch of water.Energy of wind is transferred tothe waterSize = dependent on type ofwind blowing
  • 26. Big Wave Surfing
  • 27. Wave EnergyFactors determining size andenergy of waves: Wind speed Duration of wind Fetch
  • 28. Fetch: the distance travelled by winds over open waters
  • 29. Wave MovementsAll waves have twomovements Swash Forward movement of waves Carries materials up the shore Backwash Backward movement due to gravity Carries materials back toward the sea
  • 30. What causes a wave to ‘break’?
  • 31. Types of WavesConstructive Waves Waves that build up a coastDestructive Waves Waves that erode a coastSee p.89
  • 32. Constructive WavesLow energy wavesOccurs on gentle-sloping shoresShort wave heightLonger wave intervalStronger swash and weakerbackwashDeposits materials more than iterodes
  • 33. Constructive Waves
  • 34. Destructive WavesHigh energy wavesOccurs on steep-sloping shoresWaves are tallShorter wave intervalStronger backwash andweaker swashErodes more than it deposits
  • 35. Destructive Waves
  • 36. ConstructiveDestructive
  • 37. Checkpoint 1 Explain why some waves tend to be more destructive. Describe the difference between constructive and destructive waves.
  • 38. Coastal Processes Eye for Geography, Pg. 92
  • 39. By the end of the lesson…You should be able to…1.Describe the three coastal processes2.Their factors
  • 40. Coastal Processes
  • 41. Coastal Erosion CASH: Corrasion/Abrasion Attrition Solution Hydraulic action
  • 42. Coastal Processes
  • 43. Coastal Erosion Types of waves Recap: constructive vs. destructive waves Recap: wave energy
  • 44. Coastal Erosion Amount of protection Natural (Headlands vs. Bays) or man-made structures (Engineering measures) may protect coasts from prevailing winds and destructive waves See p.97, 102
  • 45. Why are some rocksmore easy to erode than others?
  • 46. Coastal Erosion Composition of rocks Lines of weaknesses Cracks or joints Hardness Granite vs. clay Solubility Limestone vs. slate
  • 47. Coastal Processes
  • 48. Beaches are the most dynamic environments in the world andare constantly being sculpted by the action of waves
  • 49. Coastal Transportation Sediments are transported along the coast by longshore drift
  • 50. Recap: Wave EnergyFactors determining size and energyof waves: Wind speed Duration of wind FetchSimilarly, the longshore drift is a typeof wave that is determined by: Direction of wind
  • 51. The Longshore DriftCOAST DIRECTION OF CURRENTSEA SWASH BACKWASH SEDIMENT
  • 52. How to explain Longshore Drift:1. The waves approach the coast at an angle, depending on the direction of the wind.2. The swash will bring along materials to deposit on the coast at that angle.3. However, due to gravity, the backwash will drag some materials back into the sea at a perpendicular angle.4. The materials which are dragged back will then be picked up by the next oncoming swash, creating a zig-zag movement of sediments along the coast known the longshore drift.
  • 53. COAST 2 4 6 BACKWASH H AS SW1 3 5 DIRECTION OF CURRENTSEA
  • 54. Coastal Processes
  • 55. CoastalDeposition Occurs when the waves are low in energy RECAP: constructive waves.
  • 56. DepositionalFactors: Supply of materials More materials = more energy required = more deposition Gradient of slope Gentler slopes = gradual displacement of wave energy = more deposition Position of coast Sheltered areas = less exposure to wind = less destructive waves
  • 57. Exposed Headlands Protected Bays
  • 58. Exposed HeadlandsProtected Bays
  • 59. Coastal Processes
  • 60. Checkpoint 2 Describe two factors that affect coastal erosion. [4] With a well-labelled diagram only, explain the process of longshore drift. [6]
  • 61. Coastal LandformsEye for Geography, Pg. 95
  • 62. Cliffs and Wave- Cut PlatformsCliff: steep rock faceWave-cut platform: flat, rockysurface found at the base of a seacliff and exposed during low tides
  • 63. CliffWave-cut platform
  • 64. How are they formed? Cliff Wave-cut platform
  • 65. Stage 1
  • 66. Stage 2A wave-cutnotch if formed
  • 67. Stage 3The notch/s expandsinto a cave/s
  • 68. Stage 3 Guess what happens next?
  • 69. Stage 4Overhanging ‘roof’collapses
  • 70. When the tide is high, only Stage 5the cliff face is visible
  • 71. Stage 5
  • 72. When the tide is low, anunderlying rock platform Stage 5is exposed
  • 73. Stage 5
  • 74. Stage 5
  • 75. How are they formed?1. Wave erosion via hydraulic action and abrasion attack lines of weakness on the rock surface forming a notch overtime2. As erosion continues, the notch will further develop into a seacave.
  • 76. …(continued)3. Further erosion will deepen the cave until the overhanging roof becomes unstable and collapses, leaving behind a steep rock face known as a cliff.4. This process is repeated, causing the cliff to retreat further inland over the years while a gently sloping wave-cut platform, that is exposed during low tides, forms at the base.
  • 77. Coastlines are not always straight or even
  • 78. Sometimes, they can look like this:
  • 79. And this…
  • 80. Headlandsand Bays Protruding areas along a coast Indented areas along a coastline
  • 81. Headlands Bay
  • 82. See videoExposed Headlands Protected Bays
  • 83. Hanauma Bay, Hawaii USA
  • 84. San Sebastián, Spain
  • 85. THERE IS ANOTHER WAY…
  • 86. Ha Ro rd ck So ft R oc Hard k R ock Sof tR ockHa r dR ock
  • 87. How are they formed?Formed from coastswith alternate strips ofhard and soft rocksAs the waves poundagainst the coast, thesofter rock layer willerode faster thanharder rock layer.
  • 88. …(continued)The areas made ofsofter rocks will thuscurve inwards to formbaysThe harder rock layerswill remain behind,protruding out to thesea, formingheadlands.
  • 89. Wave Refraction (p.97-98)
  • 90. Wave Refraction (p.97-98)A common phenomenonassociated with headlandsand baysRefraction: means to bend/divert/deflect
  • 91. Hence why beaches tend to be found in bays……and cliffs/shore platforms are found at headlands.
  • 92. Wave RefractionRefraction: means to bend/divert/deflectWith constant erosion alongthe headlands and depositionalong the bays, the indentedcoastline will eventuallystraighten out.
  • 93. Quiz 31. What are shore platforms and how are they formed? [4]2. Why is deposition more dominant at the bay areas? [2]
  • 94. BeachA depositional landformUSUALLY consisting of fine,sandy materials and sedimentsBut can be made up ofcoarser materials too.
  • 95. CoastalDepositionRECAP: Occurs when the waves arelow in energy Q: What factors that affectdeposition?
  • 96. DepositionalFactors: Supply of materials More materials = more deposition Gradient of slope Gentler slopes = gradual displacement of wave energy = more deposition Position of coast Sheltered areas = less exposure to wind = less destructive waves
  • 97. Spits Long narrow ridges of sand deposits projecting out from the coastline and into the sea
  • 98. TombolosA spit that has joined up to anoffshore island
  • 99. St Ninians Isle,Shetland Islands,Scotland
  • 100. East Coast Park
  • 101. How are they formed?Materials are alsotransported by longshorecurrents that flow parallelalong the coastWhen there is an abruptturn in the coastline, thematerials continue to bedeposited in the same Swashdirection. Backwash
  • 102. Back…(continued)Over time, the depositsaccumulate and riseabove the water,forming a spit.As the spit continues togrow, it may join up to anearby offshore islandand a tombolo is Swashformed. Backwash
  • 103. Land Spit Island Longshore Drift ion ect Dir Sea veWa
  • 104. Land Tombolo Island Longshore Drift ion ect Dir Sea veWa
  • 105. CoastalManagement Eye for Geography, Pg. 101
  • 106. By the end of the lesson…Let’s all be able to…1.Evaluate the effectiveness of strategies in managing coastal processes
  • 107. Coastal ManagementWhy do we need to protect our coasts? Are coasts important? How so? (see Telegraph Article)
  • 108. Kingscliff in New South Wales , Australia 2006  2012
  • 109. Questions to consider:1. Why is the beach important to the locals?2. How serious is the damage? What makes you say so?3. What is causing the rapid erosion?4. How have the locals been affected?
  • 110. Importance to humans Many of the worlds major cities are located along coasts  ports facilitated trade Tourism and recreation. In Singapore, erosion along reclaimed coasts are threatening the safety of nearby residents and users of the beach.
  • 111. Environmental importance Coastal areas serve as an important habitat for many plants and animals  mangrove forests, coral reefs, deltas etc. May hold potential cures to human diseases Protect the land from natural disasters  tsunamis, flood etc.
  • 112. ApproachesHard Engineering Construction of physical structures to defend against wave erosion. Effects are immediate but often expensive and unsustainable.Soft Engineering Uses ecological principles and practices to manage erosion. Effects not immediate but cheaper and more sustainable.
  • 113. Case Studies
  • 114. Gabions Gabions are wire cages filled with small rocks piled up and placed along the coast
  • 115. Gabions
  • 116. GabionsPros + They are able to absorb and dissipate wave energy hence preventing coastal erosion. Can be used to strengthen other measures. Cheap and easy to construct.
  • 117. Easthead, West Sussex, EnglandA large sandy spit thatwas rapidly eroding dueto wave action.Gabions used to reinforcethe narrow sandy hingethat separated it from themainland.
  • 118. GabionsCons – Gabions offer only short-term protection (< 15 yrs) as the cages rust easily. Need to be vigilant about maintenance  expensive The cages are also an eyesore and dangerous when broken  wire ends are sharp and can cut
  • 119. Seawalls What possible problems do you foresee?Describe what you see here How does this structure prevent erosion?
  • 120. SeawallsSeawalls are solid concrete walls builtparallel along the coastline.
  • 121. Pros They absorb and deflect wave energy away from the coast Especially good for cliffs. Examples: see readings and textbook!
  • 122. Pondicherry, India
  • 123. Vancouver, Canada
  • 124. Cons May collapse over aperiod of time as waveenergy is redirected to thebase, resulting in a strongerbackwash. This can cause it todestabilize and collapse. Thus, constantmaintenance and repairshave to be made. Example?
  • 125. Kamaishi & Fukushima, Japan
  • 126. Breakwaters Breakwaters are solid structures made of granite built away from the coastline or, with one end still attached.
  • 127. BackBreakwatersPros + Causes waves to break against it before reaching the coast hence preventing coastal erosion. Example: Portland Harbour, England  Was effectively expanded through the construction of an offshore breakwater  protected the coastline from the destructive waves while creating a zone of calm water for the ships to dock.
  • 128. BackBreakwatersCon - Only the zones behind the breakwaters are protected leaving exposed areas of the coast to erosion. Coastline becomes very uneven and unnatural. Example: breakwaters have been constructed along East Coast Park, in Singapore  only protected certain portions from erosion.
  • 129. Groynes Groynes are solid walls usually made of granite or wood built perpendicular to the coast.
  • 130. GroynesPro + They disrupt the flow of longshore drift, thereby encouraging deposition on the side of the groyne facing the drift. For example, groynes have been built along the beach in Eastbourne, England and have helped to ensure that it remains wide enough to be effective.
  • 131. GroynesCon – It disrupts the replenishment of materials downdrift  beach becomes thinner. Ruins the natural shape of the coastline. Can wear and age overtime  need money to maintain.
  • 132. Too much?
  • 133. E.g. Since 1995, the managementcouncil in Eastbourne has spentover £30 million on reinforcing the94 timber groynes along the beach.
  • 134. BeachNourishmentDescription: Beach nourishment refers to the addition of large quantities of sand to a rapidly ‘thinning’ beach.
  • 135. Beach Nourishment Beneficial as by extending the width of the beach, areas behind are protected so long as the added sand remains. Example: Used extensively along the beaches in Singapore (e.g. East Coast). Has been successful in buffering against the effects of coastal erosion thus far and is a popular weekend destination for locals.
  • 136. a re re ! he ns roject) t t tio h P Bu ita eac m exico B li M id on(se ev
  • 137. Beach Nourishment However, importing sand is expensive and costs millions of dollars Example: Miami Beach, Florida  over US$64 million was spent on importing sand If left unprotected, the deposits will still erode away eventually  unsustainable? Damage to marine life Example: Sentosa Island, Singapore. Sand used to reclaim land and form artificial beaches  corals and small marine animals in the area were permanently smothered and destroyed.
  • 138. Re-planting mangroves Mongroves A unique type of rainforestfound along muddy coastal environments where waters are calm and high in salt.
  • 139. Re-planting mangroves Importance: prop roots buffer shorelines from the erosive impacts of waves and storms. Acts as a sponge, absorbing and slowing down the flow of flood waters inland.  Example: after the 2004 Tsunami disaster  villages in Sri Lanka protected by mangroves recorded a lower death toll  Since then, other reforestation projects have been organized (e.g. Aceh, Indonesia, see video)
  • 140. BackRe-planting mangroves However, not all coastal regions or climates can support mangroves. If the waves are too destructive or violent, re-planting would be futile  seedlings will be swept away. Example: West coast of Ireland  temperate climate not suitable for mangroves + large, destructive waves due to long fetch as winds blow over Atlantic Ocean
  • 141. West Coast of Ireland
  • 142. BackRe-planting mangroves Planting mangroves can also cause the shore to become shallower hence affecting port activities Example: Singapore – mangroves were cleared in the 1970s to make way for land reclamation projects. Replanting is not feasible anymore as the waters in these areas are used extensively for industrial and recreational purposes.
  • 143. Mangroves???
  • 144. Stablising Sand DunesRefers to the strengthening sand dunes byre-planting vegetation such as small treesand shrubs along the coast. (See Greenbelt Report Video)
  • 145. Stablising Sand Dunes This is effective as vegetation will help to trap sand and allow the dunes to build up overtime  the dunes act as natural barriers to coastal erosion. They also act as a natural ‘sand reservoir’, replenishing the sand along the beach during storm erosion.
  • 146. Example: Spencer Park Beach, New Zealand.Local council has been actively re-plantingnative dune vegetation along the beach toencourage the restoration of sand dunes,
  • 147. BackStablising Sand Dunes However, human activities will need to be minimized as trampling can occur  will destabilize the already fragile dunes  difficult to enforce and regulate Public needs to be educated on the management schemes  encourage public interest and support for the management objectives.
  • 148. Example: Spencer Park Beach, New Zealand.Newly planted grasses are fenced up usingchicken wires to protect the them from trampling
  • 149. Example: Spencer Park Beach, New Zealand.Walkways and signs have also been put up toguide visitors to the beach without needing tocross the dunes themselves
  • 150. Growth of Coral Reefs Coral reefs are underwater structures made from calcium carbonate. They form some of the most diverse ecosystems on Earth. They protect the coast by functioning as natural breakwaters, weakening wave energy as they approach the shore.
  • 151. Artificial Reefs Artificial reefs: created by placing eco- friendly structures on the sea floor  e.g. old shipwrecks Successful example: Florida  over 2,700 artificial reefs, many created by sinking old ships  have since gone onto become lucrative diving hotspots.
  • 152. Artificial ReefsCONTROVERSY!If unsuitable materials are used (e.g.rubber)  contaminate the marineenvironment by rusting or leakingtoxins into the water.Countries and businesses can use it asan excuse to leave their junk in theocean.
  • 153. Case Study:Osborne Reef, FloridaSee NY times article: Tires Meant to Foster Sea Life Choke It Instead
  • 154. “…its like the moon or something. Its weird, itdoesnt look like anything you could imagine, its justtires for as far as you can see...” - Army Diver Jason Jakovenko
  • 155. EPIC FAIL
  • 156. Even the US NAVY got involved!
  • 157. Growth of Coral ReefsUltimately the success is dependent onthe cooperation of local industries,environmentalists and governments.
  • 158. Relocation of Property Refers to the relocation of structures along the coast where erosion is inevitable Also involves the setting up of a setback line along the coast where no new developments are allowed to be built. Example: the East Coast of England has a ‘green line’ policy that discourages any developments beyond a given line.
  • 159. Relocation of PropertyBenefits Ensures shorefront developments are set back far enough so that it will not be threatened by erosion in the near future.Drawbacks However, coastal developments are highly lucrative and people with strong investment interests will oppose.
  • 160. Example: Waikiki Beach, HawaiiIgnorance and over-development along theshorelines has resulted inaccelerated erosionalong the once pristinebeach.See article and video on BeachErosion in Hawaii
  • 161. Fujiazhuang Beach, China
  • 162. ApproachesHard Engineering Construction of physical structures to defend against wave erosion. Effects are immediate but often expensive and unsustainable.Soft Engineering Uses ecological principles and practices to manage erosion. Effects not immediateb but cheaper and more sustainable.
  • 163. End
  • 164. Question Using named examples, evaluate the effectiveness of strategies used to manage and protect around the world. [8 marks]
  • 165. Step 1: State your point • An example of coastal management would be seawalls.
  • 166. Step 2: Describe thecharacteristics of your point • An example of coastal management would be seawalls. • Seawalls are solid walls made of resistant materials such as concrete, rocks, or wood. They are built parallel along the coastline.
  • 167. Step 3: Assess the effectivenessusing place-specific examples • They are effective in managing coastal erosion as they absorb and deflect wave energy away from the coast. • Seawalls were built along the coastline of Pondicherry, India and were highly effective in mitigating the effects of the 2004 Indian Ocean Tsunami on the town when it swept through the region.
  • 168. Step 4: Assess the ineffectiveness using place-specific examples • However, seawalls may collapse overtime if not maintained as wave energy is redirected to the base of the wall, resulting in a strong backwash that erodes the land beneath. They are also very expensive and can be overtopped by larger than expected waves • In Kamashi, Japan, despite the presence of the US$1.5 billion dollar seawall along the coastline, the town was badly ravaged when higher than expected waves surged through the town, overtopping the walls.
  • 169. Question Using named examples, evaluate the effectiveness of strategies used to manage and protect around the world. [8 marks] For a qn like this, you should have at least 2 well-explained measures, broken up into 2 well-structured paragraphs.