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[O] Geography(Pure) Smart Guides

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  1. Topic I: Coasts(Physical)

    1. How and why are coastal environments different and dynamic?
    5 Topics
  2. 2. Why are coastal areas valuable?
    4 Topics
  3. 3. How can we manage coastal areas in a sustainable manner?
    2 Topics
  4. Topic II: Living with Tectonic Hazards(Physical)
    4. Why are some areas more prone to tectonic hazards?
    2 Topics
  5. 5. What landforms and associated tectonic phenomena are found at plate boundaries?
    3 Topics
  6. 6. How do people prepare for and respond to earthquakes?
    3 Topics
  7. Topic III: Variable Weather and Changing Climate(Physical)
    7. Why do different places experience different weather and climate?
    7 Topics
  8. 8. What is happening to the Earth’s climate?
    5 Topics
  9. 9. Is the weather becoming more extreme?
    4 Topics
  10. Topic IV: Global Tourism(Human)
    10. How does the nature of tourism vary from place to place?
    2 Topics
  11. 11. Why has tourism become a global phenomenon?
    3 Topics
  12. 12. Developing tourism at what cost?
    2 Topics
  13. Topic V: Food Resources(Human)
    13. How and why have food consumption patterns changed since the 1960s?
    6 Topics
  14. 14. What are the trends and challenges in the production of food crops?
    4 Topics
  15. 15. How can the problem of food shortage be addressed?
    1 Topic
  16. Topic VI: Health and Diseases(Human)
    16. What are the global patterns of health and diseases?
    3 Topics
  17. 17. What influences the spread and impact of infectious diseases?
    3 Topics
  18. 18. How can we manage the current and future spread of infectious diseases?
    4 Topics
  19. Topic VII: Geography Skills and Investigations
    19. Map Reading
    11 Topics
  20. 20. Tourism Fieldwork
    1 Topic
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FACTORS AFFECTING WAVE ENERGY

Wind speed
The faster the wind blows, the greater the wave energy is
Duration of wind
The longer the wind blows, the larger the waves are
Fetch
The greater the fetch, the more energy the waves have

WAVES

Waves in the open ocean:

Have Long wavelength and a Low wave height. Water particles in the open ocean move in an orbit, a motion that rapidly decreases with depth. Water particles do not make full orbits, causing any object to move slightly forward in the ocean.

Waves close to the coastline:

  1. NEAR THE COASTLINE
    The water is shallow and the waves interact with the sea bed. The waves start to change their shape at a depth that is equivalent to about half of their wavelength.
  2. NEARER THE COASTLINE
    As the waves continue to move in the shallow water, the base of the wave starts to slow down due to friction. This causes the wave height to increase and the wavelength to decrease.
  3. NEAREST THE COASTLINE
    The base of the wave stops but the wave crest becomes steeper and topples over. This causes the waves to break onto the coast, releasing the energy of the wave. These waves also trap air to form white foams. When energy from within a wave is released on the coast, it breaks down rocks along the coastline into smaller particles. These particles are then moved away to other parts of the coast.

HOW DO WAVES AFFECT COASTAL AREAS?

  • Swash and backwash
    As the waves approach the coast, they slow down and break. When waves break, water rushes up the beach, and we call this swash.
    As swash moves up the beach, it carries sediments with it. Swash loses energy due to gravity and friction with the land and returns to the sea as backwash. The backwash carries sediments from the shore into the sea.

TYPES OF WAVES

Constructive waves

  • Constructive waves break far from the shore and with little energy. In such Low energy wave environments, finer material is deposited, which forms gentle slopes. They occur in calm weather on gently sloping coasts. Constructive waves have a strong swash but weak
    backwash.
  • Landforms such as beaches are constructed by strong swash accompanied by weak backwash. The strong swash deposits sediments on the coasts while the weak backwash removes only limited materials. Over time, the coasts are built up by the deposited sediments, forming sandy beaches.
  • wave frequency: 6 to 8 per min
  • aka swells and spilling breakers
  • occur on gentle coastal slope and sheltered coast

Destructive waves

  • Destructive waves break violently on the shore with high energy. In such high energy wave environments, finer materials tend to be transported away by the turbulent water, leaving only coarser materials which form steeper slopes. There is often a steep slope that causes the waves to break and plunge directly back down the beach.
  • Destructive waves produce a weak swash but a strong backwash. Instead of depositing sediments on coasts, destructive waves erode coasts and transport rocks and beach material away.
  • wave frequency: 10 to 14 per min
  • aka plunging and surging breakers
  • occur on a steep slope and open coast

WAVE REFRACTION

Wave refraction is the process by which waves change direction as they approach a coast. Waves tend to converge on headlands, giving rise to increased wave height and greater erosive energy. However, when waves approach bays, they diverge, resulting in decreased wave height and reduced erosive energy. This occurs as parts of the wave that reach shallow water first slow down while the other parts of the wave continue at the
same speed.

When waves approach a relatively straight coast at an angle, they are refracted and break almost parallel to the coast. The impact of wave refraction on the shoreline is uneven.

Wave refraction Process:

  1. Waves approach a headland and bend towards it. More erosion will occur at the
    headland where wave energy is concentrated
  2. Waves diverge when they reach the adjacent bays. More deposition will occur in bays
    where wave energy is spread out.
  3. Headland will retreat further inland due to erosion
  4. There will be more deposition at bays, straightening the coastline
  5. The cycle repeats