Water and Geomorphological Processes Learning Centres

Learning Centre 1: Wave definitions

Fill in the definitions for the features of a wave.

· Wave crest: _____________________________________________________

· Wave trough: ____________________________________________________

· Wave height: ____________________________________________________

· Wave length: ____________________________________________________

· Swash: _________________________________________________________

· Backwash: ______________________________________________________

Draw a diagram of a wave. Use the definitions above to label your diagram.

Learning Centre 2: Types of waves

Use the computers at this station to access http://www.curriculumbits.com/prodimages/details/geography/geo0003.html

Use the information provided to fill in the table below.

Characteristics of Deconstructive Waves

Characteristics of Constructive Waves

Label the diagrams below.

Learning Centre 3: Coastal Topography

The shape of the coastline and its orientation to oncoming waves is also an important factor to consider. Its orientation it may be sheltered from destructive waves. In small bodies of ocean or coastlines that are protected by offshore barriers or islands, prevailing wind is unable to influence wind direction and so waves approach the coast parallel to the shore. In this case coasts are said to be swash aligned. Swash aligned beaches build up large beaches with possible dunes that offer protection from erosion. For coastlines exposed to large open ocean, prevailing wind dominates wind direction and waves approach the coast at an angle. These coasts are said to be drift aligned and associated with long shore transportation of sediment. Generally these coasts have narrower beaches and may, depending on geology, be exposed to higher rates of erosion.

Look at the photographs of Maroubra Beach and Coogee Beach. Compare and contrast the coastal topography of these two beaches.

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Explain how the topography of Maroubra Beach effects the formation of waves.

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Maroubra Beach:

https://www.google.com.au/maps/@-33.9509184,151.2607,2340m/data=!3m1!1e3

Coogee Beach:

https://www.google.com.au/maps/@-33.9233351,151.2614923,2358m/data=!3m1!1e3

Learning Centre 4: Coastal Erosion

The sea shapes the coastal landscape. Coastal erosion is the wearing away and breaking up of rock along the coast. Destructive waves erode the coastline in a number of ways:

· Hydraulic action. Air may become trapped in joints and cracks on a cliff face. When a wave breaks, the trapped air is compressed which weakens the cliff and causes erosion.

· Abrasion. Bits of rock and sand in waves grind down cliff surfaces like sandpaper.

· Attrition. Waves smash rocks and pebbles on the shore into each other, and they break and become smoother.

· Solution. Acids contained in sea water will dissolve some types of rock such as chalk or limestone.

Look at the photograph of Maroubra’s north headland.

Describe how this headland may have been formed.

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Predict what may happen to Maroubra’s north headland in the future.

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Maroubra’s North Headland

http://en.wikipedia.org/wiki/Maroubra,_New_South_Wales

Maroubra Beach’s storm water outlet

http://richardelliot.blogspot.com.au/2010/10/coogee-to-maroubra.html Learning Centre 5: Longshore Drift

There are various sources of the material in the sea. The material has been:

· eroded from cliffs

· transported by longshore drift along the coastline

· brought inland from offshore by constructive waves

· carried to the coastline by rivers

Waves can approach the coast at an angle because of the direction of the prevailing wind. The swash of the waves carries material up the beach at an angle. The backwash then flows back to the sea in a straight line at 90°. This movement of material is called transportation.

Continual swash and backwash transports material sideways along the coast. This movement of material is called longshore drift and occurs in a zigzag.

Look at the photograph of the storm water outlet on Maroubra Beach. Draw a diagram of Maroubra Beach and show how the storm water outlet may effect longshore drift.