Coastal Revision Ppt


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A large presentation based on the full AS level coastal environments course with a little bit of everything for revision purposes

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Coastal Revision Ppt

  1. 1. Coasts AS Revision
  2. 2. Transportation Landforms Classification Waves Sand Dunes Erosion Importance Management COASTS
  3. 3. Importance <ul><li>Why are costs important? </li></ul>
  4. 4. <ul><li>Economic sites for industry and fishing </li></ul><ul><li>Habitats and ecosystems </li></ul><ul><li>Tourism and recreation </li></ul><ul><li>Coastal Protection </li></ul><ul><li>Defence and development </li></ul>
  5. 5. Inter Coastal Zone Management <ul><li>1992 – Earth Summit (Agenda 21 Ch.17) Protection of the Oceans </li></ul><ul><li>Climate Change </li></ul><ul><li>1993 – World Coast Conference </li></ul><ul><li>All of these and more have pointed to the need for sustainable management of the diverse issues affecting coasts today </li></ul>
  6. 6. <ul><li>Successful ICZM requires 3 stages </li></ul><ul><li>Stage One – Development and understanding of systems and processes </li></ul><ul><li>Stage Two – Use knowledge to create a sustainable long term environmentally acceptable plan </li></ul><ul><li>Stage Three – Implementation and enforcement as well as education </li></ul>
  7. 7. Waves <ul><li>Oceans cover 70% of earth’s surface </li></ul><ul><li>Coast is the narrow overlap between land and sea </li></ul><ul><li>Waves and tides are used to divide the coast into zones </li></ul>
  8. 9. Waves In Deep Water <ul><li>Swell – Often travelled large distance </li></ul>
  9. 10. Shallow Water Waves <ul><li>when the depth is less than one twenty-fifth of their wavelength </li></ul><ul><li>water particle orbits inside the wave become elliptical rather than circular as the “up-down” component of the motion is “squeezed” by the presence of the bottom </li></ul>
  10. 11. Breaking Waves <ul><li>Spilling breakers </li></ul><ul><li>Plunging breakers </li></ul>
  11. 12. Wave Refraction
  12. 13. Tides <ul><li>Oscillations of the sea surface </li></ul><ul><li>Tidal movements </li></ul>
  13. 14. Erosion <ul><li>Action of the waves </li></ul><ul><li>Sub Ariel processes </li></ul>
  14. 16. Sub Ariel <ul><li>Those from above </li></ul><ul><li>Wind </li></ul><ul><li>Rain </li></ul><ul><li>Cold </li></ul><ul><li>Heat </li></ul><ul><li>Human </li></ul>
  15. 17. Factors Effecting Rates Of Erosion <ul><li>Breaking Point of Wave </li></ul><ul><li>Wave Steepness </li></ul><ul><li>Depth of Sea – length of fetch and shape of coast </li></ul><ul><li>Supply of beach material </li></ul><ul><li>Beach Width </li></ul><ul><li>Lithology </li></ul>
  16. 18. Transportation
  17. 19. Longshore Drift
  18. 20. Landforms <ul><li>Landforms are created by erosional processes </li></ul>
  19. 21. Wave Cut Platform
  20. 22. Tombolos
  21. 23. Barrier Islands <ul><li>Develop on coasts with high energy waves and low tidal ranges </li></ul>
  22. 24. Formation <ul><li>Seen on eastern coast of North America, where they extend from New England south to Mexico. </li></ul><ul><li>long, narrow, offshore deposits of sand or sediments that parallel the coast line. </li></ul><ul><li>formation of barrier islands is complex and not completely understood </li></ul><ul><li>current theory is that barrier islands were formed about 18,000 years ago when the last Ice Age ended </li></ul><ul><li>glaciers melted and receded sea levels rose, flooded areas behind the beach ridges </li></ul><ul><li>rising waters carried sediments from those beach ridges and deposited them along shallow areas just off the new coast lines </li></ul><ul><li>Waves and currents continued to bring in sediments </li></ul><ul><li>In addition, rivers washed sediments from the mainland that settled behind the islands and helped build them up </li></ul>
  23. 25. <ul><li>Barrier islands serve two main functions: </li></ul><ul><li>they protect the coastlines from severe storm damage . </li></ul><ul><li>they act as habitats that are refuges for wildlife </li></ul>
  24. 26. Factors affecting landforms
  25. 27. Rock Structure and Shape
  26. 28. Sand Dunes <ul><li>They grow when sand is deposited on the beach by longshore drift or shoreward movement of sediment sand accumulates into ridges which originally lie parallel to the direction of the prevailing winds </li></ul><ul><li>Sand dunes are dynamic elements of the landscape </li></ul>
  27. 29. Pioneer Stage - Foredunes <ul><li>pioneer species form on dunes. Tolerant of salt such as Marram grass </li></ul><ul><li>They stabilize new dunes with their networks of root systems. </li></ul><ul><li>Each plant can also spread sideways by up to 3 metres a year, helping to trap the sand and keep it in one place. </li></ul>
  28. 30. Yellow (White) Dune Stage <ul><li>begin to show a greater diversity of plants as conditions become more favourable </li></ul><ul><li>As plants die and decay, a humus layer builds up and this traps both water and nutrients </li></ul><ul><li>more shelter and less salt spray. Marram usually still dominates the vegetation </li></ul><ul><li>Plants may include creeping fescue, sand sedge, mosses, lichens, sea holly and sea spurge </li></ul><ul><li>dunes by this stage may well have reached 5-10 metres in height </li></ul><ul><li>Rabbits and other mammals may add their droppings to help enrich the developing soil </li></ul>
  29. 31. Grey Dune Stage <ul><li>much more stable, mosses and lichens fill the remaining spaces vegetation cover may reach 100% </li></ul><ul><li>Marram grass becomes less common </li></ul><ul><li>Red fescue, sand sedge, sea spurge begin to dominate </li></ul><ul><li>Small shrubs (gorse, buckthorn) appear for the first time </li></ul><ul><li>50-100 metres from the sea </li></ul><ul><li>humus begins to darken the surface layers a true soil begins to form </li></ul><ul><li>commonly 10 metres in height and wider than those dunes nearer the shore </li></ul>
  30. 32. Dune Slacks <ul><li>dune slacks are found in between the more mature dunes where the water table reaches the surface causing seasonal or even permanent waterlogging and surface water </li></ul><ul><li>Plants which are well adapted to these damp, sheltered hollows include rushes, sedges, cotton grass and creeping willow . If decay is slow, a peaty soil may develop </li></ul>
  31. 33. Mature Dunes <ul><li>Most found several hundred metres from the shore </li></ul><ul><li>these dunes develop a soil which can support shrubs and trees </li></ul><ul><li>Humans may plant fast-growing conifers which flourish in the sandy soil </li></ul>
  32. 34. Fragility
  33. 35. Coastal Classification <ul><li>Johnson 1919 </li></ul><ul><li>Emergent – fall in sea level </li></ul><ul><li>Submergent – rise in sea level </li></ul><ul><li>Stable – no change </li></ul><ul><li>Compound – mixture of two of the above </li></ul>
  34. 36. <ul><li>Shepard 1963 </li></ul><ul><li>Primary – Influence of sea is minimal: (fjords [Glaciers], deltas [Rivers], islands Volcanic]) </li></ul><ul><li>Secondary – Marine processes dominate e.g.. Headlands and bays, spits etc </li></ul>
  35. 37. <ul><li>Valentin 1952: </li></ul><ul><li>Advancing – marine depositation or uplift of land dominates </li></ul><ul><li>Retreating – Where marine erosion or submerging land dominates </li></ul>
  36. 38. Sea Level Rise <ul><li>Thermal Expansion of the oceans – warmer water is less dense than so occupies greater area </li></ul><ul><li>Melting of small alpine glaciers </li></ul>
  37. 39. <ul><li>Tectonic Coasts Inman and Nordstrom 1971: </li></ul><ul><li>Diverging plates - Red Sea </li></ul><ul><li>Converging plates – Island arcs Japan and Philippines </li></ul><ul><li>Major transform faults - California </li></ul><ul><li>Stable plate boundaries – India and Australia </li></ul>
  38. 40. <ul><li>Energy Produced Coastlines Davis 1980 </li></ul><ul><li>High Energy environments – Where destructive waves are more typical </li></ul><ul><li>Low energy environments – Where constructive one prevail </li></ul><ul><li>Protected Environments – Wave action is limited </li></ul>
  39. 41. Coastal Management
  40. 42. Case Studies <ul><li>Holderness – Coastal Erosion </li></ul><ul><li>Formby Sand - Dunes </li></ul><ul><li>N. Carolina - Barrier islands </li></ul>