Task 1 Add information to the table below that gives specific information about location and use in Grand Bahama - In Blue!! Dune Stabalisation: Dune Cliff Regrading: This means stabalisation is planting make cliffs less steep. Cliffs vegetation on the berm of the often become unstable beach or on the dunes. By because of undercutting. By planting vegetation you should reducing the angle you should be making them more stable reduce the undercutting and (roots) and reducing the the risk of the cliff collapsing. moisture content (root uptake). Beach Nourishment: This is simply adding more sand to the Cliffs Beach or Cliff Drainage: beach. Beaches are natural often collapse because they defences, so by making them become saturated and the bigger, you are creating a increased stress causes them natural defence. Sand is to collapse. By removing some sometimes taken from the sea of the excess water you should bed or dunes inland. reduce stress on the cliff. Managed Retreat: This is not Gabion: Gabion also uses always a popular solution, large boulders, but this time the because it is basically allowing boulders are placed in cages. the sea to take back land. Low The gabion absorbs the power value land is often chosen to of the waves. be flooded by the sea. By allowing this you are changing The gabion can be installed some inland ecosystems by quickly and again is fairly adding salt water. This not the effective. However, it also looks same as doing nothing! Some ugly, reduces access and can areas are sacrificed to save be expensive. others Rip-rap or rock armour: Giant Groynes: Groynes stop boulders placed at the foot of longshore drift transporting
Task 1 Add information to the table below that gives specific information about location and use in Grand Bahama - In Blue!! Dune Stabalisation: Dune stabalisation is planting vegetation on the berm of the beach or on the dunes. By planting vegetation you should be making them more stable (roots) and reducing the moisture content (root uptake). Cliff Regrading: This means make cliffs less steep. Cliffs often become unstable because of undercutting. By reducing the angle you should reduce the undercutting and the risk of the cliff collapsing. Beach Nourishment: This is simply adding more sand to the beach. Beaches are natural defences, so by making them bigger, you are creating a natural defence. Sand is sometimes taken from the sea bed or dunes inland. Beach or Cliff Drainage: Cliffs often collapse because they become saturated and the increased stress causes them to collapse. By removing some of the excess water you should reduce stress on the cliff. Managed Retreat: This is not always a popular solution, because it is basically allowing the sea to take back land. Low value land is often chosen to be flooded by the sea. By allowing this you are changing some inland ecosystems by adding salt water. This not the same as doing nothing! Some areas are sacrificed to save others Gabion: Gabion also uses large boulders, but this time the boulders are placed in cages. The gabion absorbs the power of the waves. The gabion can be installed quickly and again is fairly effective. However, it also looks ugly, reduces access and can be expensive. Rip-rap or rock armour: Giant boulders placed at the foot of Groynes: Groynes stop longshore drift transporting
ppt13_coastal_defence_intro_sheet.docx