The Topography of Beach Waves

Teahupoo: Teahupoo is said to be the longest and heaviest wave in the world. The unique shape and the effect of almost breaking below sea level is due to the specific shape of the reef beneath the wave. The shape of the reef at Teahupoo is so unique that it is almost an impossible find. Waves formed at Teahupoo come from deep water and enter shallow water dramatically as the water climes 350 meters in a distance of only 50 meters. This instantly throws the wave over into a gigantic plunging wave able to fit a truck. Teahupoo comes to life during the summertime when the big south swells are active. These swells occur when high and low pressure systems merge causing intense wind and air pressure to create high waves and long wave lengths. Most of the best days at Teahupoo seem to happen when there is virtually no wind and it is perfectly flat.

Peahi: The Peahi waves need specific, rare weather conditions to reach there extreme heights. Because ocean swells large enough to produce this kind of surf occur only during winter months, primarily between December and February, they typically coincide with very strong winds which have a large effect on the surf. Other swells, particularly the small but powerful trade wind swells, can make the surf choppy and difficult to ride. This is caused by high pressure in the Pacific causing bumpy and vigorous waves as wind speeds intensify. The reef and rocks at "Jaws" are shaped in a way that magnify incoming swell energy and produce clean and well defined  waves with gigantic plunging sections.


Cribbar: The reef at Pipe is a flat tabletop reef, with several caverns on the inside, creating a giant air bubble that pops on the front of the wave when the wave lurches upwards just before breaking. Sand can build on the reef at Pipeline, and that can cause waves to "close out". This means the hollow tube of the wave collapses all at once making it impossible to surf. A strong current from the west, caused by low pressure systems, clears out the sand in the reef, and after that, a strong north swell can create the best waves. The Summer months create these waves as Low Pressure systems mix with High Pressure Systems causing fetch and wave height to increase creating a large area of mixed waters.
When the reef is hit by a north swell, the peak becomes an A-frame shaped wave. As the size at Pipe increases, Second Reef on the outside starts breaking, with longer walls and more size. At an extreme size an area called Third Reef even further outside starts to break with giant waves.

The Science of Big Waves

Pre-viewing:

1. Where do ocean waves come from? What gets them started?

The waves begin thousands of miles off the coast and are created by wind, fetch and duration. This constant force drives energy through the water as they increase in size and strength.

2.      What do you think a surfer should know about waves before they try and ride a wave while surfing?

A surfer should know about the intensity and speed of waves before they try to ride it as some can rock tectonic plates. They should understand that the height and intensity of waves is just way to overwhelming for a basic surfer.

Question for the Video:

1. Observe all the waves that you see and describe how they form and break. Use as many words found in the segment for you descriptions.

When wind increases waves are formed which increase in size and strength when approaching the shore line. The energy within the waves form constant cycles beneath the water as it moves. When this energy hits low land, the cycles are compressed causing the wave to increase in height, strength and intensity creating a long wavelength.

2. Describe how waves are formed, how they originate, and how they are measured?

Waves are formed when the climate is just right, thousands of miles from the impact zone. The wind and fetch intensifies resulting in waves which approach coastlines. Waves are measured by three things: Wave Height, Wave Length and Period (the time between two waves)

3. What is a maverick wave and what is special about the way it is formed?

A maverick wave is a wave which crashes on the California coast in Maverick. These waves are formed by Low Pressure Systems in the South and High Pressure Systems in the North during November, December, January and February. In-between these two pressure systems, the intensifying waves gather strength. In Maverick, there is a large layer of rocks near the shore which is what creates these mammoth waves

4. How is energy stored and transferred during wave?

When wind, fetch and duration pick up, energy is densely stored under the water in a chain of circular cycles. When this energy hits the coast, it turns into enormous amounts of kinetic energy as the water falls under the weight of gravity into swash.

5. List any kind of advice given by the surfers about how to survive these “big waves.”

When surfing, be extremely careful to be at the right position to surf as these large waves can shake a continent. If you have to wait for another wave, do so, you don’t want to take a risk with these monsters and be caught under the wrath of the Gods.

Quiz 3 Definitions

7.4
erosion-accretion cycle: The cycle of eroded material creating sand dunes and fore dunes
groynes: Constructed perpendicular to the beach to catch sand and make beaches wider
revegetation - The re-plantation of vegetation after sand dunes
sea walls - Built to stop erosion of the coastline and to protect property

7.5
rock wall: A wall made out of rock
beach nourishment: A process by which sediment lost by longshore drift is replaced by sediment from outside the beach.
sand bar: When large storms cause sand to be moved into the ocean creating platforms of sediment

7.7
environmental impact study - The study of environmental impacts on the coast
impact assessment - The study of damage and effects to the environment

7.3 Geographical Processes shaping the Coastal Environment

1. The three key geographical processes that shape the coastal environment are:

·         Erosion

·         Transportation

·         Deposition

2. Wave refraction is when water bends and is caused due to headlands and the contours of the ocean floor.

3. Waves are refracted and energy is concentrated around headlands and more dispersed along beaches located in bays.

4. The most common erosional features found on coasts are around headlands.

5. The three wave action processes that shape headlands are:

·         Hydraulic Action: When water is compressed into cracks due to waves which cause erosion and create blowholes

·         Corrasion: When wave action moves rock and other material across the rock shelf and wears away the rock

·         Corrosion: When waves break they rocks. When it dries, the salt in the sea water crystallises and acts on the minerals in the rock to erode material

6. The Erosion-Accretion Cycle:

During severe storms beaches can lose large quantities of sand through erosion by waves. This sand will often be deposited offshore, forming a sand bar off the beach where it helps to limit the impact of the erosive waves on the coast. The sand that is removed will be eventually returned naturally by smaller waves restoring the beach.

7. The three forces that shape depositional landforms of beaches are:

·         Wind

·         Waves

·         Prevailing Ocean Currents

8. The most common depositional landforms found along the coastline are beaches.

9. Coastal dunes are formed by the action of the wind. When sand is deposited on the beach it is then subject to wind transportation. The wind blows the sand landward and is captured by low lying vegetation. The foredune may be eroded away or continue to grow. If it is eroded, the plants can grow back very quickly and the dunes can form again. 

The role of vegetation in the coastal dunes cycle plays a highly important role as they are the foundation of sand dunes.

10. When waves travel at an angle, longshoredrift occurs. Once waves crack, they start to loose their energy. As the swash travels up the beach it slows until gravity causes it to go back. The water will then be hit by the next wave and the sand will be transported up the coast.

11. Blowholes: As waves crash into the headland, water can be forced into cracks and crevasses causing erosion and thus creating blowholes.

Sea stacks: Sea stacks a made when sea  gradually erodes soft limestone cliffs.

Tombolos: Due to shallow water, water refracts and bends to cause erosion. This erosion stays at a constant force causing areas of land to stick out.

Offshore Sand Bar’s: When storms occur near the coast, loads of sand is taken out to sea causing large masses of sand called sand bars.

12. Fore dunes play an important part in protecting coastal areas as they provide a buffer zone for the fragile dune vegetation located on the hind dunes. When eroded, plants return and dunes are created again.

13. a.) The Twelve Apostles are located on the Great Road in Victoria

b.) They are a popular tourist location as they are very rare, beautiful and are made up of rock from 20 million years ago.

c.) The Twelve Apostles were made due to wave erosion on the coastal headlands

d.) The ‘London Bridge’ was a natural bridge that linked the mainland to offshore rock which collapsed in January 1990.

e.) No, I do not think that the collapse of the landforms could have been prevented as the erosion of waves and the transportation of weathered material is an unstoppable cycle.
14. Good Afternoon, My name is William Gulson and this is the Port Campbell National Park. As you can see, the Twelve Apostles over there stick out independently and are an amazing site known world wide. These beautiful creations are known as seastacks that are made of rock formed up to 20 million years old. The plateau behind the beach was actually joined to these rocks millions of years ago and were slowly eroded by the sea waves as refraction compressed energy into certain spots. Things like sand and rock material continuously rubbed the limestone causing these 12 rocks to stand out. In 1990, the most famous feature called London Bridge, which was a natural arch linking the mainland to offshore sea sadly collapsed. Eventually the rest of these seastacks will eventually fall apart as erosion will continue to attack these monuments.
15. Residents of a residential property were stunned earlier this week when a proposal from the local council stated that they would like to buy back the area. Local residents who own the property say the council is depriving them of their spectacular views, relaxed lifestyle and valuable property. Some of the residents believe that this is a just decision as it is believed that a neighboring fore dune is subject to major erosion. Although, there are still many shocked and appalled by the decision and there have been many letters of complaint sent to the council. Those of the property displeased with the offer have formed a group and have been discussing these offers. One woman stated, "Why should we have to move for this bloody council, I paid could money for my house and am not throwing it away". Although, an elderly man and his 70 year old wife stated, "Yes, it has been a growing concern that the wave erosion would soon get to us." In my opinion, I believe that the local council can't do such things to people that own the apartments. You cannot just put them on the street!

Quiz 2 Definitions

7.3
Aeolian - The transportation of sand via wind
Spinifex - Low-lying vegetation which traps sand blown by the wind
Constructive Waves - Waves which deposit eroded material
Corrasion - When waves crash over rock shelves moving rock and other material causing erosion  
Corrosion - When water on rock dries causing the salt in the sea water to crystallize and act on minerals to erode material
Refraction - When waves bend to the headlands and the contours of the ocean floor
Deposition - The transport and deposited material which has been eroded by the ocean
Destructive Waves - Waves which erode material
Erosion - The transportation of weathered material which wears down  material due to wind, water etc
Hydraulic Action - When waves force air into cracks and holes in headlands causing blow holes
Longshore Drift - The transportation of sand along beach in a zig-zag movement

Waves - Water on the Move

1.     Waves are formed in three stages by the action of the wind blowing across the ocean. First the wind forms ripples, then these form wavelets and finally waves.

2.    The fetch is the distance the wind travels over the ocean to form a wave. It is an important factor in determining the size and speed of a wave as it is influenced by the strength of the wind and the length of the fetch.

3.    Waves in the open waves cause things to move in an up and down motion only and tend to be contained and have a longer wavelength. Waves closer to the shore interact with the sea floor causing the speed to decrease, the wavelength to decrease and the top of the wave to travel faster than the base, cracking the wave.

4.    

5.     

                     

6.    Spilling Waves: These are fairly light waves which break far from the shore on beaches with gentle slopes.

Plunging Waves: Break on beaches where the slope is moderately steep. These are waves which create tubes for surfers to surf in.

Surging Waves: Occur on very steep beaches. The waves role up the steep face rather than breaking over it. They cause erosion.

7.    Wind Swell: Marked by a short wavelength and high frequency of waves hitting the coast.

Ground Swell: Has a longer wavelength and the waves hit the coast less frequently.

8.    Dear Tourist,

How are you enjoying the beaches? The three types of waves you have to look out for are:

Surging Waves – Don’t worry these are harmless and are found in very deep beach slopes with little waves.

Spilling Waves – These are slightly stronger than Surging Waves and are found in very shallow waters which break far from the coast.

Plunging Waves – These are very strong so be careful. These are found in moderately steep waters which cause tubes where surfers surf.

So have fun and enjoy your time in Australia!

9.    Today was reasonably quiet and started off sunny. In the morning the beach was reasonably well covered by people as it was very sunny and hot. By around mid-day, the sky had darkened and clouds had begun to cover the sun. Most people left except the surfers as they wanted to pick up the storms waves. The wind, wave height and length had increased significantly by the early afternoon creating a few ground swells, forcing me to move the red and yellow flags to areas non-affected. By 3:00, rain and lightning was spotted in the distance and was forced to close the beach. A cyclone had begun to form in the distance.

7.1 Geographical Issues in the Coastal Environment

1. The settlement pattern of Australia is related to issues in the coastal environment as people are the leading cause to coastal environment issues. Pollution and introduced plants are some of the leading causes behind the change in coastal environment as 80% of Australians live within 50km of the coast.
2. The sustainable development of the coastline is the aim of coastal management strategies as the coast is effected by pollution, population growth, Tourism and recreational pressures, introduced plant and inappropriate development.
3. Population growth has been labelled 'sea change'.
4. Some towns along the east coast of Australia have imposed residential caps and a population ceiling of their town in an effort to stop overdevelopment of the area.
5. Population Growth: The migration from rural areas of Australia to the coastal regions.
    Pollution: Humans have treated the coast badly by leaving various rubbishes and plastics changing ecosystems along the coast.
    Tourism and Recreational Pressures: Humans increase the population during holidays placing pressure on the infrastructure and the environment surrounding the area.
     Introduced Plants: Australia introduced the Bitou Bush from South Africa to stabilize sand dunes overtaking vegitation across the beach areas.
6. Geographers assist the development of management solutions to issues in coastal environments by assisting with residents, tourists and commercial-related activities.
7. b.) I for one think that the construction of these amazing flats shows just how luxurious life can be. To be able to sit in your room watching the ocean and the beach just bellow you is staggering. I had been living in one of the Holdfast Shores flats for 2 years now and so far, my life has been one big holiday ever since.

Quiz 1 Definitions

7.1:
Breakwaters: A barrier that breaks the force of a wave
Silting: When earth or sand is deposited as a sediment
Tidal Flushing: When water enters an area due to high tides
Sea Change: The rapid increase of beach populations
Urban Stormwater: The pollution of water due to urbanisation
Dredging: The removal of sand, mud etc from harbours, rivers etc
Introduced Plants: Plants new to an area

7.2
Ground Swell: A large swell in the ocean caused by a long wavelength hitting the beach
Plunging Waves: A type of wave which forms tubes for surfers to ride
Spilling Waves: Waves which break far from the shore used for body surfing
Surging Waves: Waves which role up the shore instead of breaking over it causing erosion
Wind Swell: A swell in the ocean caused by a short wavelength hitting the beach.
Wave Height: The height of a wave
Wavelength: The distance between two waves
Fetch: The distance the wind travels to form a wave
Surf and Swash Zone: The area where waves a broken causing erosion and decomposition