Please enable JavaScript.

Coggle requires JavaScript to display documents.

Coast, IMG_E6106, IMG_E6108 - Coggle Diagram

- - - - Development of energy from wind blowing across the sea
      - Ocean is transferred to the water surface
      - Movement of wind is affected by wind direction
      - Onshore wind push waves towards the coast, resulting in waves crashing onto shore
    - - Wind duration
        
        The longer the wind blows, the larger the waves are
        
        Greater wave energy
      - Fetch
        
        The greater the fetch, the more energy the waves have
      - Wind speed
        
        The faster the wind blows, the greater the wave energy is
    - - When waves break, water rushes up a beach( Swash)
      - Swash loses energy due to gravity and friction with land, and returns to the sea( Backwash)
    - - Constructive waves
        
        Characteristics
        
        Low gradient, low energy environment
        
        Small, low waves
        
        Long wave height
        
        Long wave length
        
        Wave frequency: 6-8 per minute
        
        Swash > backwash
        
        Occur on gentle coastal slope and sheltered coast
        
        Deposition process more prominent
      - Destructive waves
        
        Characteristics
        
        Steep gradient, high energy environment
        
        Large, high waves
        
        Short wave length
        
        Wave frequency: 10-14 per minute
        
        Backwash more powerful than swash
        
        High wave height
        
        Occur on steep coastal slope and open coast
        
        Erosion process more prominent
    - - Defintion:
        
        Process by which waves change direction as they approach a coast
      - Occurs as waves slow down due to interaction with the sea bed as they move towards the coast
      - Impact of wave refraction on the shoreline is uneven
      - Process:
        
        Waves tend to converge on or bend towards headlands, giving rise to increased wave height and greater erosive energy
        
        Waves encounter friction with the headland as they approach the coast, causing them to slow down and break onto it
        
        When waves approach bays, they diverge or bend away, resulting in decreased wave height and reduced erosive energy
        
        Parts of the wave that reach shallow water first slow down while other parts of the wave continue at the same speed
    - - Coastal erosion
        
        Hydraulic action
        
        When waves strike against a rock surface, the waves trap air in the rock joints
        
        Air is compressed by oncoming waves, exerting pressure on joints
        
        As air repeatedly compressed, the joints weaken and the rocks shatter
        
        Abrasion
        
        As waves break, sediments carried by waves such as sand and rocks are hurled against the rocks
        
        Loosened sediments knock and scrape against the coastal cliffs
        
        Weakens the surface and breaks down the coast
        
        Overtime, the impact from abrasion is powerful enough to undercut a cliff
        
        Attrition
        
        When rock particles are carried by the waves rub or hit against one another, they break down into smaller pieces and become more smoothen and more rounded overtime
        
        Solution
        
        Sea water reacts chemically with water-soluble minerals in coastal rocks and dissolves them
        
        When solution of minerals occurs, rocks are weakened and eventually disintegrate
    - - Movement of materials along the shore by wave action which happens when waves approach the beach at angle
      - The swash carries the materials up and along the beach
      - The Backwash carries the materials down at the beach at right angles
      - Process slowly moves materials along the beach and provides a link between erosion and deposition
      - Spits
        
        Definition:
        
        A long narrow ridge of sediments with one end attached to the land
        
        Formed by longshore drift
        
        When there is an abrupt bend in the coastline, longshore drift may continue to transport materials in original direction for some distance
        
        When there is an abrupt bend in the coastline, longshore drift may continue to transport materials in the original direction for some distance
        
        Materials are deposited in the sea after the bend where they accumulate over time along the original direction of the coastline
        
        This forms a ridge of sediments from the point where the coastline change direction
        
        A hook or curve may develop at one end of the spit, most likely to wave refraction concentrating at that point
        
        Tombolo
        
        A spit has one end connected to a mainland and has another end projecting out into the sea
        
        Spit may continue to extend until it connects the offshore island to the mainland
  - - - These parts of the headlands will be eroded more quickly, especially by hydraulic action and abrasion
      - Wave attacks at the weakness at the base of the headland and undercut it
      - Forms a cave at the area that is hollowed by wave action
      - Within headlands, some rocks may be less resistant to erosion than other rocks
    - - Caves may develop on each side of the headland
      - Erosion may eventually join caves together, leaving a bridge of rock known as an arch above the opening
- - - - Where people farm fishes in fisheries like cage enclosures in coastal areas with water and contributes up to 33% of the world's fish supply
    - - Ca Mau, Vietnam
    - - Shrimp production in 2010 valued U$800 million
    - - Coastlines are prone to erosion and pollution and its high in maintenance cost in running the farm sustainable way
  - - - Where fisherman built stilt houses standing in water
      - Boats served as transportation and communication while they do their business
    - - Kukup, Malaysia
    - - Attractive tourist destination, with its economy largely driven by the income earned from local and foreign tourist
      - Money is also made from fishing which is the main source of economy
    - - Catching in close proximity makes fisherman susceptable to diseases
      - Intense waves of the coast make it hard to build the stilt houses
  - - - Involves temporary movement of people, primarily for leisure or recreational purposes
      - Coastal areas that are sandy and bright make an ideal hotspot for tourism
    - - Sentosa, Singapore
    - - Building of tourism infrastructure like resorts or
        theme parks as well as conservation of marine ecosystems
    - - -Building of tourism infrastructure may require
        more land space.
      - Limited land space
      - Dumping of sediments into the sea, which may be harmful to aquatic life
- - - - Coral reefs are structures that develop at, or slightly below sea level on the
        seabed
      - They are built and made out of thousands of tiny animals known as coral polyps,
      - secreting rock-like deposits of calcium carbonate to protect their soft and delicate
      - They are built and made out of thousands of tiny animals known as coral polyps,
    - - Between the Tropics of Capricorn and Cancer
      - Along coasts where sea is shallow. The Southeast Asian Region has the largest
        area and the highest biodiversity of coral reefs in the world.
    - - Salinity of 34-37 per thousand is optimal per thousand is optimal
      - A moderate amount of water movement ensures that corals receive sufficient amount of oxygen
      - Sea surface temperature not lower than 17 to 18 degrees centigrade
      - Clear, saline water between 10 to 60 metres deep allows sufficient sunlight to penetrate allowing algae
        photosynthesis
      - Turbidity of water must be low enough to allow sufficient sunlight to penetrate
    - - Allows small marine animals like parrot fish to feed on the dead algae and breed as it
        also serves as a breeding ground
        
        Example:
        
        support about 25% marine fish species worldwide. It also shelters them from
        larger predators like sea snakes
      - Absorbs and reflects some of the wave energy to reduce erosion
      - The ability of corals to support natural ecosystems by providing homes to different
        species allows others to find their sources of food.
        
        Example:
        
        Fishermen can use coral reef sites to hunt for fish as coral reefs are home to
        many fish species
    - - Over-collection of coral reefs
        
        Corals are collected and used for souvenirs or commercial use.
        
        The over-collection of corals weakens and disrupt the coral ecosystem, thus endangering them
        
        Example:
        
        Philippines
        
        Red
        Sea in Egypt
      - Fishing methods
        
        Releases cyanide which poison the coral reefs, killing them.
        
        Spearfishing uses electric powered spear gun to hunt fishes
        
        Selective depletion of fish populations disrupts the ecosystem’s food
        chain.
        
        Example:
        
        Indonesia
        
        Philippines
        
        Netherlands
        
        Elize Bonaire
      - Recreation of coast
        
        Expansion of resort leads to discharge of waste into the sea
        Boat’s oil spillage pollutes seawater
        
        This damages and kills the corals from suffocation as both activities blocks sunlight from reaching the algae on the corals that provide them oxygen
        
        Example:
        
        Sri Lanka
      - Coastal development
        
        Land reclamation and extension involves dumping rocks and
        sediments which suffocate and destroy the coral reefs
        
        Coral reefs are suffocated by sediments and are destroyed
        
        Example:
        
        Japan
        
        Florida, USA