Case Study- Mangawhai-Pakiri Coastline: Unintentional consequences of economic development Location = East coast of New Zealand’s Northland Peninsula. Reasons for economic development = High quality sand for modern economy; glass, concrete, beach replenishment...
Eustatic = Changes in volume of water in global ocean store. Isostatic = Changes in land-level. Physical factors include variations in earth’s orbit around the sun (400,000yrs), variations in solar energy (ll yrs), atmospheric composition due to volcanic eruptions and...
Raised Beaches and Abandoned Cliffs: Areas of former shore platforms that are left at a higher level than present sea level. • Inland from present coastline, possibly with abandoned cliffs, wave cut notches, caves, etc behind beach. • After emergence no longer...
Shingle Beach: When sea levels fell as the volume of land-based ice grows, areas of ‘new’ land emerged from the sea. As sea levels rose former coastal sediment is pushed onshore by wave action. • Sediment accumulates on new land due to river deposition, meltwater...
Case Study- Adelaide Metropolitan Beaches: Human and physical factors affecting coastal landscapes Location = City in S Australia, Indian Ocean and Great Australian Bight to the South. Unintentional changes = Littoral drift north and sand removed for development...
Beaches: Formed by the accumulation of material deposited between high and low tides. As sediment size increases so does beach angle. Storm beach – Storm waves hurl pebbles to back of beach. Berms – Smaller ridges that develop at high tide mark. Cusps – Small,...
Wind: Aeolian energy is the primary source for other processes. Influence wave type created by frictional drag of wind on water. Fetch is the distance of open water the wind blows over and prevailing wind is the most frequent wind direction. Waves: • Formation =...
Sediment budget: The balance between inputs and the removal of sediment. Positive budget is accretion of material on shoreline, negative budget causes the shoreline to recede landwards. Human – Beach nourishment Offshore – Marine deposition Terrestrial – Fluvial (90%...
Mechanical Weathering: • Freeze thaw = Water expands in rocks by 10% when frozen. Pressure causes splits. • Pressure release = Underlying rock fractures parallel to surface as it expands when overlying rock is removed. • Thermal expansion = Rocks expand when heated...
Cliffs and wave-cut platforms: • High energy waves concentrate erosion at cliff base. • Cliff undercut to form wave-cut notch. • Undercut cliff collapses and retreats, leaving a gently-sloping forefront (wave-cut platform). • Wave cut platform extended by abrasion,...
Inputs = Kinetic energy from wind/waves. Sediment from weathering, mass movement and fluvial discharge. Outputs = Aeolian and marine erosion, dredging and mining and offshore sediment transfer. Throughputs = Stores of beach sediment and flows such as longshore drift....