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Should Coastal Environments Matter?

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Presentation on theme: "Should Coastal Environments Matter?"— Presentation transcript:

1 Should Coastal Environments Matter?
CHAPTER 1 COASTS Should Coastal Environments Matter?

2 CHECK-IN: Surfing a monster wave
JR: linked the hyperlink to the photo Alternative link of the same event: Description for teacher: Garrett McNamara, a Hawaiian surfer caught a gigantic 24-metre tall wave off the coast of Praia do Norte, Portugal. This is the biggest wave ever surfed and Garrett is now in the Guinness Book of World Records. He beat the previous record by a foot about 30 centimetres. BBC News reports that the monster wave was located above an underwater canyon that is famous for generating these huge waves. McNamara has also been awarded $15,000 for his achievement at the Billabong XXL Global Big Wave Awards in California. Adapted from: Questions for students: Are all waves this size? No, smaller waves can be found on the beach. Make some guesses as to why waves are of different sizes? What caused this wave to be so big? According to the article, there are deep canyons below this area where the wave formed. That could have caused the wave to be big. The wind could be very strong here causing the waves to be big. 3. Which part of the ocean can one find such high waves? Further out in the ocean where it’s deeper. 4. What will happen if a wave this height reaches the beach where there are human activities? It could wash away houses or structures along the coastline. It could destroy lives and buildings. 5. Is this different from a tidal wave as in a tsunami? Tsunami is generated by plate movement in oceanic plates whereas this particular wave was generated due to the presence of deep canyons below the water surface together with wind energy allowing the waves to build up this height and move at high energy Note: Qn 1-3 leads onto KQ 1 which explores the dynamism and differences within a coastal environment. Qn 4 explores the impact of waves on the human environment. Qn 5 explores more difficult questions which teachers can choose to come back to at the end of this chapter, if students are ready for more information.

3 CHECK-IN: Which photograph represents the coastline
CHECK-IN: Which photograph represents the coastline? Explain your choice. 4 2 3 1 What is a coastal environment? Zones within a coastal environment For Express students: With reference to the four photographs, identify the characteristics of a coastal environment. Possible answers: A coastal environment spans across a large area. It consists of the area where the beach meets the ocean (photo 1), areas further out in the ocean (photo 2), areas right behind the high tide mark where trees and grass grow (photo 3) and areas where the waves cannot reach (photo 4). A coastal environment consists of the beach where there is sand and tall waves. For NA students: Compare the four photographs. What are the main features of the coast in each photograph? Photo 1 has large waves and a beach Photo 2 has a tall wave Photo 3 and 4 show that trees and grass growing on the sand away from the water

4 CHAPTER 1 COASTS Should Coastal Environments Matter?
In this Chapter, you will explore three key questions: How and why are coastal environments different and dynamic? Why are coastal areas valuable? How can we manage coastal areas in a sustainable manner?

5 CHAPTER 1 COASTS Should Coastal Environments Matter?
KQ 1: How and why are coastal environments different and dynamic? What is a coastal environment? (zones) What are the differences within coastal environments? What factors lead to the difference and dynamism in coastal environments? How do coastal processes differ? How do coastal processes shape coastal landforms differently

6 a. What is a coastal environment? (zones)
Cross reference to slide 1 to reinforce the horizontal zones that make up a coastline and define the spatial demarcations of a coastal environment.

7 CHAPTER 1 COASTS Should Coastal Environments Matter?
KQ 1: How and why are coastal environments different and dynamic? What is a coastal environment? (zones) What are the differences within coastal environments? What factors lead to the difference and dynamism in coastal environments? How do coastal processes differ? How do coastal processes shape coastal landforms differently

8 b. What is the difference between coastal environment?
What are the differences in the characteristics of the following coastal environments? Lulworth Cove, Britain Waikiki Beach, Hawaii Compare the four photographs. For Express: Students can be given the task without much scaffolding. Allow them to learn how to compare on their own. For NA: Divide the class into groups of four or five. Instruct each group to select two photographs to compare. Guide students with the comparison. For example, students can compare in physical terms -- shape of the coastline AND type of features (sediments, rocks, sand, vegetation) found along the coastline OR human terms – the human activities along the coastline. Suggested answers: Shape and material found at shoreline: The Lulworth Cove is cliffed and curves inwards, forming a U-shape. The coastline has steep sloping cliffs. The Waikiki Beach is a straight stretch of sandy beach with a big rock formation jutting out into the sea at the end. Cape Kumukahi is made up of a string of rocks rocky. The beach in Bunaken is muddy, with has plants and trees growing in the water. Human activities along shoreline: The Lulworth Cove has houses and buildings on top of the cliffs. Waikiki Beach is filled with buildings and beach side structures on the beach itself. The beaches in Cape Kumukahi and Bunaken have no human activities, probably because it is not feasible for human activities to occur where there are rocks and trees. Cape Kumukahi, Hawaii Bunaken, Indonesia

9 CHAPTER 1 COASTS Should Coastal Environments Matter?
KQ 1: How and why are coastal environments different and dynamic? What is a coastal environment? (zones) What are the differences within coastal environments? What factors lead to the difference and dynamism in coastal environments? How do coastal processes differ? How do coastal processes shape coastal landforms differently

10 c. What factors lead to the differences and dynamism of coastal environments?
Waves Tides and sea level changes Currents Geology (rock composition) Types of ecosystems (e.g. mangroves and coral reefs) Human activities (e.g. trading, fishing, recreation) Suggested activity Using the following photographs of coastal landforms, suggest how some of the six factors in this slide might possibly shape the landforms in terms of their shape, size, gradient, land use, environmental state (e.g. pollution)

11 c. What factors lead to the differences and dynamism of coastal environments?
Tombolo Suggested answers: Wave energy is low and tides are low. The sand bar between two pieces of land will not be eroded away. More deposition may occur and the tombolo may become more stable. Human activities can occur on the tombolo if it is stable enough. Tombolo is formed between 2 existing islands – formed when a spit extends to a nearby island Longshore drift brings Source:

12 c. What factors lead to the differences and dynamism of coastal environments?
Spit Suggested answers: Waves push the sand particles out to sea, wave energy is high and carry large amount of sediments. Currents move in the direction that the sandbar is forming and carry the sediments there too. Occurs where the direction of the coastline changes abruptly. Longshore drift transports sand or pebbles along the coast, and continues to transport the materials in the original direction after the direction of the coastline changes. The materials are deposited in the sea where they accumulate over time. Recreational activities can occur on the spit if it is stable enough. Source:

13 c. What factors lead to the differences and dynamism of coastal environments?
Beach Sandy beach Wave energy is low and causes more sand to accumulate on the beach. Human activities may occur on the coast, at places where the high tide will not affect them. There may be coral reefs in the water in front of the beach which reduces wave energy. Source:

14 c. What factors lead to the differences and dynamism of coastal environments?
Cliffs Chalk cliffs Tide is relatively high and waves may have eroded and weakened the rocks to form the steep cliffs. The rocks are probably soft rock which erode easily from wave action. Source:

15 c. What factors lead to the differences and dynamism of coastal environments?
Waves Wind energy transferred to water Blowing across surface of seas and oceans Affects: the power of waves to erode landforms Tides and sea level changes Rise/fall in sea level Caused by gravitational pull of moon and Sun on Earth Affects: transportation of sediments (depositional landforms) and erosion JR: high/low tides don’t only cause erosion

16 c. What factors lead to the differences and dynamism of coastal environments?
Wave energy Tide Low tide High tide Sources: Wave energy:http://www.ouramazingplanet.com/2016-mystery-moving-irish-boulders.html Tides:

17 c. What factors lead to the differences and dynamism of coastal environments?
Currents Large scale continuous movement of water in seas and oceans Driven by prevailing wind in one direction Affects: sediment distribution and erosion Geology (rock composition) Composition: more/less resistant rocks; hard/soft rock Composition: layered structure Affects: rate/speed of erosion

18 c. What factors lead to the differences and dynamism of coastal environments?
Geology Spit: Headlands and Bay: Currents

19 c. What factors lead to the differences and dynamism of coastal environments?
Types of ecosystems Natural barriers Corals: Slow down speed of waves Mangroves: trap sediments and reduce coastal erosion Affects: impact of waves on coasts Human activities Built-up area along coastline Pollution of coastal environment Affects: condition of coastal environment

20 c. What factors lead to the differences and dynamism of coastal environments?
Coral reefs Mangroves Mangroves: Coral reef:

21 Chapter 1 COASTS Should Coastal Environments Matter?
KQ 1: How and why are coastal environments different and dynamic? What is a coastal environment? (zones) What are the differences within coastal environments? What factors lead to the difference and dynamism in coastal environments? How do coastal processes differ? How do coastal processes shape coastal landforms differently

22 d. How do coastal processes differ?
Wave action How would you describe the waves? 1 2 4 Suggested activity: Using the photographs, ask students about the characteristics of the waves/describe the waves shown. Wave size (What does wave size suggest about wave energy?) Wavelength Wave length (photographs 2 & 4 show a series of waves) Then, lead onto next slide about parts of a wave. Possible answers: Photograph 1 and 4 seem to have very large waves with high wave energy. The waves are curling over and the wind seems to be blowing the water at the top of the wave in photo 4. Photograph 2 & 3 have smaller waves which seem to just roll on to the beach. They probably are lower energy waves. Photograph 4 shows that there is another wave right behind the wave in the front, the 2 waves are very close to each other, with a short wavelength wave length. Photograph 2 shows a series of waves with longer wavelengths wave lengths between the waves. Photograph 1: Photograph 2: Photograph 3: Photograph 4: 3

23 d. How do coastal processes differ?
Wave action Parts of a wave Can be taught together with the diagram in the TB pg 9.

24 d. How do coastal processes differ?
Why do waves curl? Come up with a hypothesis to suggest how waves go from Photograph A to Photographs B1 & B2. Photograph A Photograph B2 Photograph B1 Wave formation A: B1: B2: Could you add some suggested hypotheses here? E.g.: “Wind speed causes waves to curl” “The distance over which the wind is blowing over the ocean/sea causes waves to curl.” “The duration of which the wind blows over the ocean/sea causes waves to curl.”

25 d. How do coastal processes differ?
Why do waves curl? What do the photographs definitely tell me? What can I infer from the photographs? What do the photographs not tell me? What further questions do I need to ask? Photograph A Photograph B1 Wave formation The wave in Photograph A is flat and is not curling like in photograph B1 and B2. The waves are calmer than in Photographs B1 and B2. The waves in Photograph A are found in the nearshore zone. B1 and B2 seems to be further out at sea. Photograph B1 and B2 are found further offshore therefore there is higher wave energy there. Therefore the waves have enough energy to curl over. There could be coral reefs or rocks under the waves in Photograph A causing the waves to be low-energy waves. What is underneath the wave? How deep is the seabed? Does the wind affect the waves? What is the climate like in the photographs? Photograph B2

26 d. How do coastal processes differ?
Why do waves curl? Wave formation

27 Match the diagrams to the factors affecting wave energy
d. How do coastal processes differ? Match the diagrams to the factors affecting wave energy Factors Fetch (distance the wave travels) Duration of wind Wind speed Wind strength 1 A 2 B C Explain that the diagrams are a plan view of the coastline. A match to 4 Note: To explain fetch, use the following website: B match to 3 C match to 1 D match to 2 3 D 4

28 d. How do coastal processes differ?
Wave Action Swash Backwash 2 wave types: Constructive & Destructive Erosion Transportation Deposition Wave refraction

29 d. How do coastal processes differ?
Wave Type Constructive dominant process: swash carries sediments onto beach at an oblique angle) Destructive dominant process: backwash carries sediments away from beach into ocean at a right angle due to gravity) NOTE: A Swash and Backwash occurs for every wave that comes onto the shore)

30 d. How do coastal processes differ?
Wave Type Constructive Waves Destructive Waves Gradient Low High Energy environment Wave height Wave length Long Short Wave frequency 6–8 per minute 10–14 per minute Swash vs backwash Swash more powerful than backwash Backwash more powerful than swash Breakers Swells and spilling breakers Plunging and surging breakers Occurs on Gentle coastal slope and sheltered coast Steep coastal slope and open coast Prominent process Deposition Erosion

31 d. How do coastal processes differ?
Wave Action Wave Refraction

32 d. How do coastal processes differ?
Wave Action Wave Refraction (approaching a coast) The process by which waves change direction when they approach a coast Occurs only when there is friction between water and seabed Change in wave speed Waves converge on headlands and diverge on bays When waves converge – increased wave height and greater erosive energy When waves diverge – decreased wave height and lower erosive energy Uneven impact on shoreline Coastal processes

33 d. How do coastal processes differ?
Wave Action Coastal Erosion Focus on: Cause (wave action, rock particle movement) & Effect (outcome of wave action with rock particles) Hydraulic action Abrasion or corrasion Attrition Solution or corrosion Coastal processes

34 d. How do coastal processes differ?

35 d. How do coastal processes differ?
Use the above diagram to illustrate the 4 different coastal erosion processes that follow For NA students: Using students as examples of rocks and the classroom wall as a cliff is a good real life illustration of the different action of rocks and waves during the different erosional processes. Source:

36 1d. How do coastal Processes differ? – Wave Action
Coastal Erosion Focus on: Cause (wave action, rock particle movement) & Effect (outcome of wave action with rock particles) a. 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. JR: Suggest deleting this slide – covered in slide 34 already

37 1d. How do coastal Processes differ? – Wave Action
Coastal Erosion Focus on: Cause (wave action, rock particle movement) & Effect (outcome of wave action with rock particles) b. Abrasion 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. JR: Suggest deleting this slide – covered in slide 34 already

38 Cliff undercut by coastal abrasion
d. How do coastal processes differ? Cliff undercut by coastal abrasion Source

39 1d. How do coastal Processes differ? – Wave Action
Coastal Erosion Focus on: Cause (wave action, rock particle movement) & Effect (outcome of wave action with rock particles) c. 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. JR: Suggest deleting this slide – covered in slide 34 already

40 Rocks rounded by attrition
d. How do coastal processes differ? Rocks rounded by attrition

41 1d. How do coastal Processes differ? – Wave Action
Coastal Erosion Focus on: Cause (wave action, rock particle movement) & Effect (outcome of wave action with rock particles) d. 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 JR: Suggest deleting this slide – covered in slide 34 already

42 d. How do coastal processes differ?
Wave Action Sediment Transport Longshore drift and longshore currents Recap: Currents Large scale movement of water in oceans Driven by prevailing wind in one direction Affects: sediment distribution and erosion

43 d. How do coastal processes differ?
Wave Action Sediment Transport Longshore drift and longshore currents

44 d. How do coastal processes differ?
Wave Action Sediment Transport Longshore currents and longshore drift Longshore currents: Flows parallel to coast, forms when waves approach coasts at an angle Resultant zigzag movement of sediments known as beach drift: Carried up the beach at an oblique angle through swash due to wind direction Carried perpendicularly down the beach through backwash due to gravity

45 d. How do coastal processes differ?
Wave Action Longshore drift: A result of both longshore currents and beach drift Sediments are deposited when they meet an obstruction. These sediments are transported by both longshore current and beach drift, which produces longshore drift. Determined by direction of wind

46 d. How do coastal processes differ?
Wave Action Sediment Deposition What are some reasons for the man being unable to carry the boxes properly? What should the man do if the boxes are too much and too heavy? Source:

47 d. How do coastal processes differ?
Wave Action Sediment Deposition What are some reasons for the wave being unable to carry the sediments? What should the wave ‘do’ if the sediments are too much and too heavy/large? Reasons for deposition: Friction, low wave energy, too much sediments, large sediments Wave deposits the large sediments.

48 d. How do coastal processes differ?
Wave Action Sediment Deposition Sediment texture Sediment type Sediment size VERY FINE Clay less than mm Coarse / fine? Silt mm to mm Coarse / medium? Fine sand 0.125 mm to 0.25 mm Medium sand 0.25 mm to 0.5 mm Coarse sand 0.5 mm to 1 mm Very coarse sand 1 mm to 2 mm Fine / coarse? Pebble 2 mm to 64 mm Cobble 64 mm to 256 mm Boulder more than 256 mm Using information about sediment type and sediment size, identify the sediment texture. The first one has been done for you. Answers: Very fine Fine Medium Coarse JR: Would suggest removing text in red (except for ‘VERY FINE’)

49 Chapter 1 COASTS Should Coastal Environments Matter?
KQ 1: How and why are coastal environments different and dynamic? What is a coastal environment? (zones) What are the differences within coastal environments? What factors lead to the difference and dynamism in coastal environments? How do coastal processes differ? How do coastal processes shape coastal landforms differently

50 e. How do coastal processes shape coastal landforms differently
Coastal features/landforms: Process leads to an outcome/characteristic of landform Cliffs and shore platforms Headlands and bays Caves, arches and stacks Beaches Spits and tombolos

51 e. How do coastal processes shape coastal landforms differently
Coastal features/landforms: process leads to an outcome/characteristic of landform Cliffs and shore platforms Hydraulic action Erosion by waves Enlarged joints Notch Cliff collapse and cliff retreat Gently-sloping platform at cliff base

52 e. How do coastal processes shape coastal landforms differently
Coastal features/landforms: process leads to an outcome/characteristic of landform Headlands and bays Different rates of erosion on rocks of different resistance Bays (wide indented inlets in the coastline) Headlands (rocks which extend into sea)

53 e. How do coastal processes shape coastal landforms differently
Coastal features/landforms: process leads to an outcome/characteristic of landform Arches, stacks and stumps Further erosion of headlands (abrasion and hydraulic action) ‘Hollowing’ by wave action Roof of cave collapses Lines of weaknesses Cave Stack (pillar of rock)

54 e. How do coastal processes shape coastal landforms differently
Coastal features/landforms: process leads to an outcome/characteristic of landform Beaches Deposition of different sized particles Erosion by strong waves Zone of deposition Made of loose sand, gravel and pebbles Gentle gradient (fine grains) Steep gradient (coarse grains)

55 e. How do coastal processes shape coastal landforms differently
Coastal features/landforms: process leads to an outcome/characteristic of landform Spits and Tombolos Longshore drift Deposition and transportation Continued longshore drift even though coastline changes abruptly Accumulated materials Spits/tombolos

56 CHAPTER 1 COASTS Should Coastal Environments Matter?
KQ 1: How and why are coastal environments different and dynamic? What is a coastal environment? (zones) What are the differences within coastal environments? What factors lead to the difference and dynamism in coastal environments? How do coastal processes differ? How do coastal processes shape coastal landforms differently


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