Coasts 2014
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Coasts 2014 Presentation Transcript

  • 1. Coasts Coast and Factors Affecting Coastal Environments
  • 2. Guiding Questions 1. Where is the coast? 2. Why are coastal environments dynamic?
  • 3. By the end of the lesson… We will be able to, 1. Define the coast. 2. Explain the factors affecting coastal environments.
  • 4. Where is the coast?
  • 5. Where is the coast?
  • 6. Where is the coast? • The area where the land meets the sea. • Covers the area of land that is affected by waves and tides.
  • 7. Factors Affecting Coastal Environments 1. Waves 2. Tides and sea level changes 3. Currents 4. Geology 5. Types of ecosystems 6. Human activities
  • 8. Waves • A wave is a long body of water that curls into an arched form which breaks onto the coast. • Waves are formed when kinetic energy from wind blowing across surface of seas and oceans is transferred to the water. • Waves affect coastal environments by serving as the main agent for the coastal processes of erosion, transportation and deposition.
  • 9. Tides and Sea Level Changes • Tides refer to the daily alternate rise and fall in the sea level caused mainly by effects of gravitational pull of the moon and sun. • Tides affect coastal environments as they determines the activity of coastal processes. For example, erosion and transportation processes are more dominant during high tides then low tides. • Changes in sea levels may release massive volumes of water into seas and oceans, thereby creating new coastlines.
  • 10. Currents • Ocean currents are large-scale, continuous movement of water in seas and oceans driven largely by prevailing wind which generally blow in one direction. • Ocean currents affect coastal environments as they carry massive amounts of energy, which influences the extent and intensity of coastal processes.
  • 11. Geology • Geology refers to the arrangement and composition of rock. • Geology affects coastal environments as more resistant rocks such as granite and basalt erodes slower than less resistant rocks such as limestone and shale. • Rocks with more cracks and joints are more vulnerable to erosion.
  • 12. Types of Ecosystems • The type of ecosystem influences coastal environments through their interactions with coastal processes. • For example, coastal ecosystems serve as natural barriers that slow down the speed and impact of waves on coasts. • Mangroves ecosystems, in addition to serving as natural barriers, traps sediments hence reduce coastal erosion.
  • 13. Human Activities • Human activities influence coastal environments through activities such as shipping, recreational activities and building and operating marine structures. • These activities can result in significant changes to the coast over short periods of time.
  • 14. Coasts Waves
  • 15. Guiding Questions 1. What influences wave energy?
  • 16. By the end of the lesson… We will be able to, 1. Describe the factors influencing wave energy. 2. Describe the different types of waves and their associated landforms.
  • 17. Wave Terminology
  • 18. Factors Influencing Wave Energy 1. Wind speed 2. Duration of wind 3. Fetch
  • 19. 1. Wind Speed • The faster the wind blows, the greater the wave energy is.
  • 20. 2. Duration of Wind • The longer the wind blows, the larger the waves are and the greater the wave energy.
  • 21. 3. Fetch • Refers to the distance travelled by winds over open seas. • The greater the fetch, the more energy the waves have.
  • 22. Waves close to the coastline
  • 23. Wave Movements • All waves have two movements. – Swash • Forward movement of waves. • Transports sediments up the shore. – Backwash • Waves that flow back to the sea due to gravity. • Transports sediments back to the sea.
  • 24. Types of waves • Constructive waves • Destructive waves
  • 25. Constructive waves Destructive waves Swash vs. backwash Swash more powerful than backwash Backwash more powerful than swash Prominent process Deposition Erosion Breakers Swelling and spilling breakers Plunging and surging breakers Wave frequency 6–8 per minute 10–14 per minute Wave height Low High Wave length Long Short Occurs on Gentle coastal slope and sheltered coast Steep coastal slope and open coast Environment Low energy High energy
  • 26. Waves and Landforms • Constructive waves form depositional landforms. – Bay – Beach – Spit – Tombolo
  • 27. Bay
  • 28. Beach
  • 29. Spit
  • 30. Tomobolo
  • 31. Waves and Landforms • Destructive waves form erosional landforms. – Headland – Cliff – Shore platform/Wavecut platform – Cave – Arch – Stack
  • 32. Headland
  • 33. Cliff
  • 34. Shore platform
  • 35. Sea cave
  • 36. Arch
  • 37. Stack
  • 38. Coasts Wave Refraction
  • 39. By the end of the lesson… We will be able to, 1. Explain the process of wave refraction.
  • 40. Wave Refraction • Refers to the process whereby wave speed and direction changes as waves encounter different depth of water.
  • 41. Wave Refraction • Wave speed is reduced and wave direction changes as waves encounter friction from the seabed. • Waves experience more friction from the steeper seabed in front of headlands and converges. • This increased wave height and wave frequency which lead to more erosion at the headland.
  • 42. Wave Refraction • Waves experience less friction from the gentler seabed when it enters the bay than the headlands and diverges. • This decreased wave height and wave frequency which lead to less erosion at the bay area.
  • 43. 1. Waves converge at the headland. 2. Waves diverge at the bay.
  • 44. Coasts Coastal Processes
  • 45. Guiding Questions 1. What are coastal processes?
  • 46. By the end of the lesson… We will be able to, 1. Describe coastal processes.
  • 47. Coastal Processes 1. Erosion 2. Transportation 3. Deposition
  • 48. Coastal Erosion • Hydraulic action • Abrasion or Corrasion • Attrition • Solution or Corrosion
  • 49. Hydraulic Action • Waves striking against a rock surface trap air in its joints. • This air is compressed by the oncoming waves, exerting pressure on the joints. • Over time, these joints weaken and the rocks shatter.
  • 50. Abrasion or Corrasion • As waves break, sediments carried by waves such as sand and rocks are hurled against the coast. • These loosened sediments knock and scrape against the coastal cliffs. This weakens the surface, resulting in the breaking down of the coast. • Over time, the impact from abrasion is powerful enough to undercut a cliff.
  • 51. Attrition • When rock particles carried by waves rub or hit against one another, they break down into smaller pieces and become smoother and more rounded over time.
  • 52. Attrition
  • 53. Solution • Sea water reacts chemically with water- soluble minerals in coastal rocks and dissolves them. • For example, limestone rocks are easily eroded by carbonic acid in solution. • When solution of minerals occurs, rocks are weakened and will eventually disintegrate.
  • 54. Coastal Transportation • Waves approach the coast diagonally/at an oblique angle and create longshore currents, which are currents that flow parallel to the coast.
  • 55. Coastal Transportation • Swash carries material up the beach diagonally/at the same oblique angle. • while backwash carries material down the beach perpendicularly/at right angle due to the pull of gravity. • This results in a zig-zag movement of materials along the beach known as beach drift.
  • 56. Coastal Transportation • Both longshore currents and beach drift transport sediments along the coast. • The combined effect of sediment movement by longshore currents and beach drift is known as longshore drift.
  • 57. Coastal Deposition • Waves deposit when wave energy decreases such that waves are unable to carry sediments. • Larger sediments are deposited first followed by smaller sediments.
  • 58. Coastal Deposition • Deposition is more dominant along sheltered coasts where destructive waves are less common.
  • 59. Coasts Coastal Landforms
  • 60. By the end of the lesson… We will be able to, 1. Explain the formation of cliffs and shore platforms/wavecut platforms.
  • 61. Cliffs & Shore Platforms • Hydraulic action and abrasion attack lines of weakness on the rock surface forming a notch overtime. • As erosion continues, the notch deepens and develops into a seacave, which is an underground chamber with an overhanging roof.
  • 62. Cliffs & Shore Platforms • Overtime, the overhanging roof collapses due to the force of gravity, forming a steep rock face known as a cliff. • The materials from the collapsed roof are carried by waves and thrown against the base of the cliff, causing further erosion. • As this process repeats overtime, the cliff will retreat inland, leaving a gently-sloping platform known as a shore platform.
  • 63. By the end of the lesson… We will be able to, 1. Explain the formation of headlands and bays. 2. Explain the formation of caves, arches and stacks.
  • 64. Headlands and Bays • Formed when alternate bands of more resistant and less resistant rocks are arranged at right angles to the coast.
  • 65. HEADLANDS AND BAYS • The less resistant rocks erodes faster than the more resistant rocks, forming wide indented coasts, known as bays. • The remaining more resistant rocks extend into the sea and are known as headlands.
  • 66. Blue Grotto, Italy
  • 67. Caves • Waves attack lines of weakness and undercut the base of headlands. • Continuous action of waves hollowed out the headland, forming a cave.
  • 68. Cabo San Lucas
  • 69. Arches • As wave action continues, adjacent caves are eventually eroded through and joins, leaving a bridge of rock known as an arch.
  • 70. 12 Apostles, Australia
  • 71. Stacks • After a period of time, the roof of the arch collapses due to the force of gravity to form a pillar of rock in the sea, known as a stack.
  • 72. By the end of the lesson… We will be able to, 1. Explain the formation of spits and tombolos.
  • 73. Spit • As the direction of the coastline changes abruptly, longshore drift continues to transport materials in the original direction for some distance. • This results in the deposition of transported beach materials into the sea, which accumulate over time.
  • 74. Spit • As the materials continue to accumulate, they eventually appear above the surface as a long narrow ridge of sand or pebbles with one end attached to the land, which is known as a spit.
  • 75. Tombolo • If an offshore island lies near the mainland where the spit is forming, the spit may continue to extend until it connects the offshore island to the mainland, forming a tombolo.
  • 76. Coasts Geographical Investigation – Beach sediment size and beach gradient
  • 77. By the end of the lesson… We will be able to, 1. Describe the relationship between beach sediment size and beach gradient.
  • 78. Let’s Investigate • Turn to page 26. • Study “Investigate This 6”.
  • 79. Let’s Investigate Site Sediment size (mm) Beach gradient (°) 1 0.35 3 2 0.6 6 3 0.4 5 4 0.3 4 5 0.25 3 6 0.3 3 7 0.35 3 8 0.4 5
  • 80. Let’s Investigate
  • 81. Let’s Investigate • Describe the relationship between sediment size and beach gradient. Support your answer with the use of figures.
  • 82. Let’s Investigate • The bigger the sediment size, the steeper the beach gradient. OR • There is a direct relationship between sediment size and beach gradient. • For example, when sediment size is 0.25 mm. beach gradient is 3°, and when sediment size is 0.6 mm. beach gradient is 6°.
  • 83. Coasts Coastal ecosystems
  • 84. Guiding Question 1. What are the ecosystem services that people can obtain from the coastal ecosystem?
  • 85. By the end of the lesson… We will be able to, 1. Describe the four key ecosystem services obtainable from coastal ecosystem.
  • 86. Ecosystem Services 1. Provisioning services 2. Regulating services 3. Cultural services 4. Supporting services
  • 87. Ecosystem Services 1. What does the coast provide? 2. What does the coast regulate? 3. What culture does the coast inculcate? 4. What does the coast support?
  • 88. 1. Provisioning Services a. Fish and other types of seafood b. Water c. Building and ornamental materials
  • 89. 1. Provisioning Services a. The coast provides fish and other types of seafood which serves as the main dietary protein for more than 1 billion people and provides employment and income for over 100 million.
  • 90. 1. Provisioning Services b. The coast also provides water as seawater can be desalinated to become drinking water. For example, Singapore practices desalination to ensure the sustainability of fresh water.
  • 91. 1. Provisioning Services c. In addition, the coast is a source of building and ornamental materials. For example, mangroves is a source of wood that can be used for building boats, houses and converted into charcoal. Corals can also be crushed and made into cement or made into ornaments for sale as souvenirs.
  • 92. 2. Regulating Services a. Shoreline stabilization b. Flood prevention c. Storm and natural hazard protection
  • 93. 2. Regulating Services a. The coast helps to stabilize the shoreline as coral reefs and mangroves cause waves to break and lose their energy, thereby reducing the impact of shoreline erosion hence protecting existing shoreline.
  • 94. 2. Regulating Services b. The coast helps to prevent floods as sandy beaches are able to disperse water and sand dunes act as natural barriers to advancing waters, thereby reducing the risk of flooding.
  • 95. 2. Regulating Services c. The coast provides protection against storms and natural hazards. For example mangroves and corals offers protection against heavy storms and tsunamis as wave energy is absorbed or reduced hence reducing the full impact of destructive waves on the coast.
  • 96. 3. Cultural Services a. Recreational benefits b. Aesthetic benefits c. Spiritual benefits
  • 97. 3. Cultural Services a. The coast provides recreational benefits as they are popular venues for leisure activities such as swimming and sailing. For example, Gold Coast, Australia, with its 60 kilometres of beach, attracts around 1o million visitors every year.
  • 98. 3. Cultural Services b. The coast also provides aesthetic benefits as they are scenic places which draw visitors who enjoy the quietness of the sea and people who appreciate nature.
  • 99. 3. Cultural Services c. Coasts are spiritual places especially for coastal communities that depend on the seas for their livelihood. For example, it is common to find temples dedicated to sea deities along the coasts of Taiwan and Bali, Indonesia.
  • 100. 4. Supporting Services a. Mangrove habitat b. Beach habitat
  • 101. 4. Supporting Services a. The coast supports mangroves habitats as the area between the roots, mud and water of mangroves provide living creatures with food, protection from predators and grounds for breeding.
  • 102. 4. Supporting Services b. The coast supports beach habitats which play key roles in the life cycles of various sea creatures. For example, fish fry swims in the shallow waters and gain size before venturing into deeper waters and sea turtles lay their eggs in the beach sand.
  • 103. Coasts People and Coastal Areas
  • 104. Guiding Questions 1. How do people use coastal areas?
  • 105. Uses of Coastal Areas 1. Fisheries and aquaculture 2. Housing and transportation 3. Tourism and recreation 4. Ports, harbours and piers 5. Wind farming 6. Desalination 7. Sand mining, salt extraction 8. Oil refining
  • 106. Uses of Coastal Areas • Fisheries and aquaculture activities are found along coast which refers to the farming of fish in fisheries or fish farms to meet the growing demand of fish. • For example, the province of Ca Mau in Vietnam is the nation’s shrimp production centre and generates US$800 million in revenue in 2010.
  • 107. Uses of Coastal Areas • Coastal areas are spaces for housing and transportation and many people make use of boats as transport to facilitate economic activities like fishing and tourism. • For example, the people living in stilt houses and floating fish farms in the coastal town of Kukup, Malaysia, uses boat ferry services to carry out their daily activities.
  • 108. Kukup, Malaysia
  • 109. Uses of Coastal Areas • Coastal areas are popular spaces for tourism and recreation activities and make up the most important component of international tourism. • For example, the pristine beaches of Sentosa, Singapore is a popular tourism honeypot that drew millions of tourists every year.
  • 110. Uses of Coastal Areas • Coastal areas are home to ports, harbours and piers which are gateways to foreign trade. • For example, the Port of Shanghai, connected by the Yangtze River, serves the vast economically-developed areas of Anhui, Jiangsu and Zhejiang and moved 650 million tons of goods in 2010 to become the world’s busiest port.
  • 111. Uses of Coastal Areas • Higher wind speeds are available offshore compared to on land, hence wind farming operations can be conducted along coastal areas. • For example, the Greater Gabbard Wind Farm off the coast of Suffolk in England is the largest offshore wind farm in the world and estimated to generate 1.75TWh per year.
  • 112. Greater Gabbard Wind Farm, England
  • 113. Lillgrund Wind Farm Sweden
  • 114. Uses of Coastal Areas • Sea water can be desalinated to produce fish water by removing salt and other minerals from the saline water to produce fresh water suitable for human consumption or irrigation. • For example Australia, being the driest continent has invested heavily on desalination plants to boost drinking water supplies that traditionally depended on rainfall collected from behind dams.
  • 115. Uses of Coastal Areas • Coastal areas are sources of sand that can be mined or extracted for nourishing erosional beaches or for construction. • For example, about 219,000 cubic metres of sand is mined yearly from Kaipara Harbour, New Zealand to produce concrete for construction and asphalt for surfacing roads.
  • 116. Uses of Coastal Areas • Oil refining refers to the processing of crude oil into refined products such as petroleum, diesel and gasoline and are commonly found along coastal areas for easy access to ports. • For example, large oil refining plants are located on the offshore island of Jurong Island, Singapore with the capacity to refine over a million barrels of crude oil per day.
  • 117. Coasts Coral Reef Ecosystems
  • 118. Guiding Questions 1. Why are costal reef ecosystems distinctive and valuable? 2. What pressures are coral reefs facing?
  • 119. By the end of the lesson We will be able to 1. Describe the global distribution of coral reef ecosystems. 2. Describe the favorable conditions for growth. 3. Explain the value of coral reef ecosystems in the coastal environment. 4. Describe the pressures on coral reef ecosystems.
  • 120. Distribution
  • 121. Distribution
  • 122. Distribution • Mostly found between the Tropic of Cancer and the Tropic of Capricorn. • Highest concentration in Southeast Asia.
  • 123. Favourable Conditions for Growth • Suitably strong wave action that brings food and oxygen supplies. • Low levels of sedimentation to prevents suffocating living corals. • Sea surface temperature not lower than 17°C. • Average salinity. • Clear water between 10 – 60m to allow sunlight to penetrate for algae to photosynthesis. • Low turbidity.
  • 124. Value of Coral Reefs 1. Supports natural ecosystems 2. Absorbs wave energy 3. Serves as tourist attractions 4. Source of materials for jewelry and ornaments
  • 125. Value of Coral Reefs 1. Coral reef supports natural ecosystems by sustaining a wide range of marine creatures to breed and grow which include more than 25% of marine fish species.
  • 126. Value of Coral Reefs 2. Coral reefs protect the coast against the full force of waves by serving as natural protective barriers that absorb wave energy generated in the open seas.
  • 127. Value of Coral Reefs 3. Coral reefs are tourist attractions that attract divers and beach goers whose activities provide jobs and income for tourist industry.
  • 128. Value of Coral Reefs 4. Corals is a source of materials for making jewelry and ornaments which can then be sold as souvenirs to tourists, thereby generating jobs and income for the local communities.
  • 129. Pressures on Coral Reefs 1. Overfishing 2. Irresponsible fishing methods 3. Recreational use of coast 4. Pollution 5. Siltation 6. Costal development 7. Climate change
  • 130. Coasts Mangroves Ecosystems
  • 131. Guiding Questions 1. Why are mangroves ecosystems distinctive and valuable? 2. What are the pressures on mangroves?
  • 132. By the end of the lesson We will be able to 1. Describe the global distribution of mangroves. 2. Describe the value of the mangrove ecosystem in the coastal environment. 3. Describe the pressures on mangrove ecosystems.
  • 133. Distribution
  • 134. Distribution • Along coasts of countries between the Tropic of Cancer and Tropic of Capricorn. • For example, in countries of Southeast Asia, Venezuela and Brazil in South America and Senegal and Sierra Leone in Africa. • Patches of mangroves north of the Tropic of Cancer along the coasts of Mexico and south of the Tropic of Capricorn along the coasts of Australia.
  • 135. Zonation of Mangroves
  • 136. Adapting to the Coastal environment • Trees such as the Avicennia have pencil-liked aerial roots that enable them to take in oxygen in waterlogged conditions.
  • 137. Adapting to the Coastal environment • Trees such as the Rhizophora have prop roots that enable them to anchor to the soft, muddy ground for stability against waves.
  • 138. Adapting to the Coastal environment • Trees such as the Bruguiera have kneed roots that enable them breathe and also serves as anchor to the soft, muddy ground.
  • 139. Adapting to the Coastal environment • Some trees such as the Rhizophora bear fruits that are javelin-shaped so they can pierce the soft mud to germinate and grow into a sapling immediately without being washed away by the waves.
  • 140. Adapting to the Coastal environment • Mangrove trees are salt tolerant and some have developed ways to secrete salt. • For example the Avicennia leaves have special glands that secrete the salt taken in from the saline water.
  • 141. Adapting to the Coastal environment • Most mangrove trees produce fruits that are buoyant, allowing them to float away and germinate in other coastal areas.
  • 142. Value of Mangroves 1. Stabilizing shorelines 2. Breeding ground and habitat 3. Wood for fuel 4. Improves water quality
  • 143. Value of Mangroves 1. Mangroves are valuable as they stabilize shorelines with their dense roots system which absorbs energy of waves and slows down the water thereby reducing coastal erosion. In addition, sediments washed down by rivers and washed up by waves are collected and deposited amongst the mangrove roots. For example, some 5 million mangrove trees were planted along the coastal areas of Malaysia since 2005 as protection against the devastating impact of tsunamis and to manage the loss of sediments.
  • 144. Value of Mangroves 2. Mangrove ecosystems are valuable breeding grounds and habitats for marine life. For example, barnacles, oysters and sponges anchor on the hard surfaces of aerial roots and shrimps, crabs and lobsters forage for food in the middy sediments between the mangrove roots.
  • 145. Value of Mangroves 3. Mangrove forests is a source of wood for fuel, construction, charcoal and feed for livestock. For example, communities living near mangroves have been known to make charcoal from wood collected from mangrove trees and feed leaves from mangrove trees to their sheep and goats.
  • 146. Value of Mangroves 4. Mangrove trees improve water quality as their dense network of roots is able to trap waste materials and fine sediments hence acting as natural filters for purifying water.
  • 147. Pressures on mangroves 1. Demand for fuel wood and charcoal 2. Need for more farming areas 3. Land reclamation 4. Water pollution 5. Rising sea level
  • 148. Coasts Threats to coastal areas
  • 149. Guiding Question • What are the threats to coastal areas?
  • 150. By the end of the lesson We will be able to 1. Identify and explain the threats to coastal areas.
  • 151. Threats to Coastal Areas 1. Climate change 2. Eroding shorelines 3. Rising populations 4. Coastal development and habitat loss 5. Pollution
  • 152. Threats to Coastal Areas 1. Climate change have led to global warming, which have resulted in rising sea levels that could submerge low-lying coasts and landforms such as sandy beaches and deltas.
  • 153. Threats to Coastal Areas 2. Shorelines are eroding more rapidly as global warming has resulted in more severe storms capable of altering shorelines over a short period time and destroy corals.
  • 154. Threats to Coastal Areas 3. Close to half of the world’s population live within 100 km of the coast and as the world’s population increases, more coastal sites will be developed and more coastal resources will be exploited, leading to coastal degradation.
  • 155. Threats to Coastal Areas 4. Habitats are destroyed when coasts are altered with human structures such as ports and resorts.
  • 156. Threats to Coastal Areas 5. Pollution is largely caused by the disposing of waste into the sea that could destroy the coast and endanger marine life. For example, the Great Pacific Garbage Patch is a mass of garbage that has accumulated in the Pacific Ocean over time.
  • 157. Coasts Sustainable Management of Coastal Areas
  • 158. Guiding Question 1. How can coastal areas be managed?
  • 159. By the end of the lesson We will be able to 1. Assess the effectiveness of strategies to achieve sustainable management of coastal areas.
  • 160. Sustainable Management of Coastal Areas 1. Limit damaging activities 2. Protect coastal resources 3. Restrict development
  • 161. Sample Question 1. Assess the effectiveness of strategies to achieve sustainable management of coastal areas. [8] – Point (Describe your point) – Explain (Explain the significance of your point) – Examples [Explain how your point is effective with the use of named example(s)] – Limitations [Explain how your point is ineffective with the use of named example(s)]
  • 162. Limit damaging activities • Point: – Damaging activities such as blasting coral reefs and clearing mangroves can be limited to reduce the damage to coastal areas. • Explain: – National and local government bodies can work together to carefully manage the needs and demands of the people together with the nature of the coastal environment.
  • 163. Limit damaging activities • Example: – For example, sand dunes stabilized by vegetation along Port Philip Bay in southern Victoria, Australia were often trampled on by beachgoers leading to the destruction of the dune vegetation, resulting in houses behind the sand dunes being partly buried by the large volume of sand. This led the authorities to fence off the dunes hence allowing the coastal environment to recover.
  • 164. Limit damaging activities • Limitation: – However, the fences make the beach look less attractive and created inconveniences for residents and visitors when navigating the beach.
  • 165. Protect Coastal Resources • Point: – Protecting coastal resources aim to prevent resources from being exploited or depleted. • Explain: – Resources such as fish, corals and mangroves can be protected so as to allow the environment to rest and recover.
  • 166. Protect Coastal Resources • Example: – For example, in Goat Island Marine Reserve, specific areas known as marine reserves are created to protect marine ecosystems and allow fish and marine creatures to breed and thrive. Due to the effort of the reserve, there is now significantly more fish in the reserve than outside it, demonstrating the success of this strategy.
  • 167. Protect Coastal Resources • Limitation: – However, protecting coastal reserves are not without problems as local communities who have been depending on the coastal resources for a living are denied from accessing resources that have supported them for a long time.
  • 168. Restrict development • Point: – Restricting development in coastal areas especially prone to natural hazards refers to the implementation of management policies to deal with the threat of natural hazards. • Explain: – Despite the occurrence and unpredictability of natural hazards, coastal areas still draw visitors and investors who often have to spend large amounts of resources to repair and rebuild after a natural hazard .
  • 169. Restrict development • Example: – For example, the Federal Emergency Management Agency of the USA ensures that structures are built away from areas prone to natural hazards. • Limitation: – However, this strategy can only be effective with strong enforcement and are normally less effective in less developed countries such as Indonesia due to rampant corruption.
  • 170. Coasts Coastal Protection Measures
  • 171. Guiding Question 1. What are the coastal protection measures?
  • 172. By the end of the lesson We will be able to 1. Evaluate the effectiveness of coastal protection measures.
  • 173. Coastal Protection Measures • Soft engineering – Protecting the coast using natural processes and does not involve the construction of any physical structures.
  • 174. Coastal Protection Measures • Soft engineering 1. Beach nourishment 2. Planting vegetation 3. Stabilizing sand dunes 4. Encouraging growth of coral reef
  • 175. Coastal Protection Measures • Hard engineering – The construction of physical structures to protect coasts against the erosive power of waves.
  • 176. Coastal Protection Measures • Hard engineering 1. Seawalls 2. Gabions 3. Breakwaters 4. Groynes 5. Tetrapods
  • 177. Sample Question 1. Assess the effectiveness of coastal protection measures. [8] – Point (Describe your point) – Explain (Explain the significance of your point) – Examples [Explain how your point is effective with the use of named example(s)] – Limitations [Explain how your point is ineffective with the use of named example(s)]
  • 178. Seawalls • Point: – Seawalls are solid walls made of resistant materials such as concrete, rocks, or wood built parallel and on the coast. • Explain: – They are effective in managing coastal erosion as they absorb and deflect wave energy from attacking the coast.
  • 179. Seawalls • Example: – For example, seawalls built along the Esplanade, Singapore has been effective in preventing erosion from affecting human properties and structures along the coast. • Limitation: – However, seawalls are costly to maintain as the backwash of deflected waves washes away the beach materials at the base of seawalls, undermining their stabilitym which will eventually lead to their collapse.
  • 180. Gabions • Point: – Gabions are wire cages filled with small rocks piled up and placed along the coast. • Explain: – Gabions are effective in preventing coastal erosion as the gaps between the rocks allow water to filter through hence weakening wave energy.
  • 181. Gabions • Example: – For example, gabions placed along Hornsea Beach, England have been effective in reducing the impact of coastal erosion. • Limitation: – However, they offer only short-term protection as the rocks are easily eroded away by waves and the cages corrode easily and are unsightly.
  • 182. Breakwaters • Point: – Breakwaters are solid walls usually made of granite built off and parallel to the coast, or with one end attached to the coast. • Explain: – Breakwaters are useful as when constructed offshore, a zone of calm water is created behind them, which encourages deposition to form beaches.
  • 183. Breakwaters • Example: – Breakwaters have been installed along East Coast Park, Singapore and have been successful in mitigating the effects of coastal erosion. • Limitation: – However, breakwaters protect the coast unevenly as only the zones behind the breakwaters are protected while exposed sections are still vulnerable to erosion.
  • 184. Groynes • Point: – Groynes are solid low walls usually made of granite or wood built on and perpendicular to the coast. • Explain: – They are useful as they disrupt the direction of longshore drift thereby encouraging deposition on the updrift side of the groyne that faces longshore drift.
  • 185. Groynes • Example: – For example, groynes built along St Leonard Beach, Canada have successfully mitigated the effects of longshore drift. • Limitation: – However, no fresh materials are deposited on the downdrift side of the groyne, which leads to an uneven and unsightly coastline.
  • 186. Tetrapods • Point: – Tetrapods are four-pronged concrete structures stacked offshore in interlocking positions. • Explain: – Tetrapods are able to dissipate wave energy as they allow waves to pass around them rather than hit against them, reducing the possibility of them being damaged by waves.
  • 187. Tetrapods • Example: – Tetrapods have been used by Crescent City, northern California, for many years as defense against the impact of tsunamis, which occurred 31 times between 1933 and 2008. • Limitation: – However, tetrapods are aesthetically unappealing and also pose a danger to swimmers, surfers and boaters.
  • 188. Beach Nourishment • Point: – Beach nourishment refers to the replenishment of large quantities of sand to the beach. • Explain: – This is useful as it extends and improves the beach and protects the beach against storms.
  • 189. Beach Nourishment • Example: – Beach nourishments applied along East Coast Park, Singapore has been successful in mitigating the effects of coastal erosion. • Limitation: – However, beach nourishment is expensive and the eroded sand that washes out to seas may destroy marine life.
  • 190. Planting Vegetation • Point: – Vegetation such as mangrove trees can be planted along the coast to manage the coastline. • Explain: – This is effective as prop roots of mangroves are able to secure and trap sediments and extend the coastal land seawards.
  • 191. Planting Vegetation • Example: - For example, mangrove trees planted along the west coast of Peninsular Malaysia has been effective in preventing coastal erosion. • Limitation: - However, not all coastal regions can support mangroves and planting mangroves can cause the shore to become shallower hence affecting port activities.
  • 192. Stabilising Sand Dunes • Point: – Sand dunes can be strengthened by planting vegetation such as small trees and shrubs. • Explain: – This is effective as sand dunes act as natural barriers to coastal erosion and by anchoring the sand, coastal erosion can be managed.
  • 193. Stabilising Sand Dunes • Example: – For example, sand dunes along Triton Place, Western Australia, have been stablisedand preserved by planting marram grass. • Limitation: – However, human activities will need to be minimised along the coasts in order to preserve the sand dunes, hence this strategy may not be effective in serving all coastal communities.
  • 194. Encouraging Growth of Coral Reef • Point: – Coral reefs can be preserved or cultivated to manage the coastline. • Explain: – Encouraging the growth of coral reefs is effective as they act as natural breakwaters that can weaken wave energy hence protecting the coast against erosion.
  • 195. Encouraging Growth of Coral Reef • Example: – For example, the Maldives have invested heavily in the cultivation of corals to protect their economic interests along the coast. • Limitation: – However, corals are difficult to cultivate and requires constant maintenance in order to grow well.
  • 196. Geographical Skills
  • 197. Plotting Scattergraph • Give your scattergraph a title • Plot the independent i.e. what you control, on the x-axis • Plot the dependent i.e. derived value from the independent, on the y-axis • Label your axes with arrowheads • Use an appropriate scale i.e. graph must take up at least 50% of the graph paper
  • 198. Constructing Beach Profile • Give your beach profile a title • Plot full length of transects on x-axis • Plot angle of elevation on y-axis • Label your axes with arrowheads • Use an appropriate scale i.e. profile must take up at least 50% of the answer sheet e.g. writing paper, graph paper • Note that angles of elevation must be actual angles measured on a protractor.
  • 199. END