Ithome 4sept 4q - Ans

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Geography Sec 3 IT Home Learning HWA CHONG INSTITUTION High School Section

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Sec 4 Q

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1a) Fig. 1 below shows two coastal regions X and Y. Identify the region that will receive greater impact from the energy of waves. Explain your answer. [3] Region Y [1m] • Due to it fetch [1m] • The greater the fetch, the more energy the waves have. Region Y has a greater fetch then X. [1m] Account for other factors that will affect coastal erosion. At least 2 factors must be mentioned. Award 1m for each identified factor. Award 1m for elaboration of factor.

[4]

Types of waves [1m] Destructive waves cause more erosion than constructive waves. [1m] Structure and composition of coastal rocks [1m] Rocks with greater lines of weaknesses (cracks and joints) and soft rocks made up of materials like shale and clay will erode faster.[1m] Position of Coast [1m] Open and unprotected coasts will erode faster than sheltered and protected coasts. [1m] b) Study photograph A which shows a coastline protected by groynes. State the direction and describe the process of longshore drift.

[5]

Direction of longshore drift: Northwest to Southeast [1m] • Waves approach the coast at an angle • Swash carries materials up the beach at an oblique angle • Backwash carries materials perpendicularly down the beach due to gravity • Zig-zag movement of the materials along the beach is known as longshore drift c) With the help of well-labeled diagrams, describe the formation of headlands and [5] bays. Award 2 marks for diagrams. At least 2 diagrams must be shown. Minus ½m for every missing label. Diagrams should include: wave direction, resistant/less resistant rocks, headlands/bays

Nancy Tay

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04/09/2009

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Exposed coast has alternate bands of resistant and less resistant rocks Less resistant rocks will be eroded faster than more resistant rocks, forming bays More resistant rocks are eroded more slowly and protrude/extend into the sea forming headlands

d) ‘Constructing groynes are more important than planting vegetation in the management and protection of coasts.’ Do you agree? Explain your answer. [8] Students may include the following materials:

Nancy Tay

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04/09/2009

Groynes

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Vegetation • • •

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Strength Constructed at right angles to the sea to trap beach materials Absorb/reduce energy of waves Materials deposited on side of groyne facing longshore drift Beach is extended and enalarged Also protect cliffs/structures behind from wave erosion Example of groynes: Coast of Eastborne, England / Sussex, UK Planting vegetation like mangroves help to trap sediments Protects coasts and reduces coastal erosion Trapping of enough sediments from roots of mangroves can form small islands Helps to extend coasts seawards and expand mangrove community Eg. Planting of mangrove seedlings in Aceh, Indonesia due to 2004 Tsunami Eg. Cordgrass planted along coast of Chandeleur islands, USA

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Weakness Erosion still takes place on coast not protected by groynes No supply of fresh beach materials on downdrift side of groynes Eyesore: groynes makes the beach less attractive

Not all coastal regions and support mangroves Destructive waves can still destroy mangrove community Depth of coasts become shallower due to build up of sediments, affecting countries such as Singapore that depend on maritime trade May cause problems to coastal navigation

Level 1 (0-3marks) Simple statements on 1 or more of the measures No examples given No reference coastal management Level 2 (4-6marks) At least 1 or more detailed statement on each measure General examples given Award 4m – one sided answer Level 3 (7-8marks) Balanced answers must be given, clear counter arguments Detailed statements on each measure

Nancy Tay

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04/09/2009

Specific examples given

Nancy Tay

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04/09/2009