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Coast by Mind Map: Coast

1. Spit

1.1. Longshore drift transport materials along coast. Sudden change in the direction of coast, longshore drift continues to transport materials in original direction to deep sea. As longshore drift enters deep water, minerals are deposited. Overtime, materials accumulate above water to form spit.

2. Erosion

2.1. Corrasion

2.1.1. Waves crash against coast

2.2. Attrition

2.2.1. Materials collide

2.3. Solution

2.3.1. Water reacts with minerials and dissolve.

2.4. Hydraulic Action

2.4.1. Cracks to widen the rocks.

2.5. Size of Waves

2.5.1. Wind energy Higher wind speed = Higher wind energy = Larger waves

2.5.2. Fetch Greater fetch = Greater energy waves have

2.6. Backwash

2.6.1. Backward movement of wave. Removes materials away from beach.

2.7. Swash

2.7.1. Forward movement of waves. Bring eroded materials onto beach.

3. Erosional Features

3.1. Headlands & Bays

3.1.1. Less resistant areas, curve inwards = Bays

3.1.2. More resistant areas, protrude out = Headlands

3.2. Cliffs and Shore platform

3.2.1. Cliffs: high, steep rocks face along coast.

3.2.2. Waves cut notch, along line of weakness

3.2.3. Further erosion, notch becomes sea cave.

3.2.4. Overhanging part collapses, forming cliffs.

3.2.5. Cliffs retreats inland. Shore platform is formed at base of cliff.

4. Transportation - Longshore Drift

4.1. Waves approach shore at angle. Swash rushes up shore diagonally, carrying materials in same direction.

4.2. Backwash returns down shore at right angle due to gravity, carrying materials in same direction. Deposited materials move along beach in a zig zag manner parallel to the coast.

5. Depositional Features

5.1. Beach

5.1.1. Beach accumulation of sediments on coast. Forms when waves deposit materials onto shore. Different types of beaches comprising of different types of materials. Constantly changing shapes and sizes. Affected by waves, tides and currents.

5.2. Tombolo

5.2.1. Spit continues to grow with continuous deposition of materials. The spit joins nearby island to mainland to form a tombolo.

6. Coastal Protection Measures

6.1. Hard Engineering

6.1.1. Groynes Eg, England is a region that uses groynes to protect its coastline. Groynes is a low wall built at right angle. To prevent materials form being transported away by longshore drift. Enables transported materials to accumulate on the side of the groyne facing longshore drift. Disadvantages. On the other side of groyne, beach will not be replenished b materials carried by the longshore drift. Beach further down may be eroded away. Series of groynes cna help to reduce this effect. Spoil the natural beauty of coastal environment.

6.1.2. Breakwaters Built parallel to the coast. Usually made of granite. Creates a zone of shallow water between itself and coast. Waves will break against it before reaching coast. Eg. Singapore Siloso Beach [Sentosa] Disadvantages. Unable to provdie complete protection as it still leaves areas of coast unprotected, Unprotected areas will be prone to erosion. Expensive to build.

6.1.3. Gabions Wire cages containing smsall rocks are used up to form a wall to protect the coast. Also protect other structures like seawalls. Disadvantages. Can be easily destroyed by powerful waves during storms. Wire rusts easily. Ruin the natural beauty of coastal environment. Cheaper than other protection measures. Short lifespan.

6.1.4. Seawall Built in front of cliff or along coast. Made of concrete which absorbs energy of waves and protects coast against strong waves. Eg. The Queen Elizabeth Walk in Singapore Disadvantages. Not protect coast from erosion in long run. As waves break against seawall, the energy of waves redirected downwards, resulting in strong backwash. Backwash erode away the base of seawall, causing to weaken and collapse. Expensive to built.

6.2. Soft Engineering

6.2.1. Coastal Dunes Ridge of sand piled up by wind on the coast. Exposed to strong winds from oceans. Vegetation trao and stabilise sand and can accumulate up to a height of 100m. Act as barriers along coast and protect human property against coastal erosion and flooding. Human activites have disturbed coastal dunes. Loss of vegetation causes sand to be easily blown inland. Can cover nearby roads etc. Eg. St. Helen on east coast of Tasminia

6.2.2. Mangroves along shore. Have prop roots or kneed root that anchor trees firmly in muddy soil. Roots also bind loose soil and protect it from erosion. Areas planted with mangroves suffered less damage. Eg. Singapore Singei Buloh

6.2.3. Beach Nourishment Adding large amounts of sands to beach that is being eroded. Bring in sand from other areas and deposit in into beach again. Eg. In 1980, Miami Beach in Florida. Disadvantages. Lasts only 10 years. Quality sand is very expensive and require regular maintenance.

6.2.4. Growth of Coral Reefs Protect beaches against coastal erosion by reducing the speed of waves. Human activites like dynamite fishing have destroyed a number of coral reefs. Water pollution aggravate the situation as corals can only grew well in clear water.