Term
| how many types of coastal deffenses are there and what are they? |
|
Definition
| 7 types - sea wall, groynes, gabions, rip-rap, revetment, offshore breakwater, beach rebuilding |
|
|
Term
| what is the most expensive and least expensive types of coastal defense? |
|
Definition
most expensive - sea wall
least expensive - beach rebuilding |
|
|
Term
| describe what a groyne is |
|
Definition
| a low wall built out into the sea that traps and reduces erosion |
|
|
Term
|
Definition
made of stone or concrete. reflects waves and withstands waves breaking on it. can also include flat decks for walking or car park.
Advantage - capable of withstanding high energy waves, efficienf and effective, strenght and height reassures public fear of flooding.
Disadvantages - High cost of building and repair, reflection can cause turbulence and scouring of the beach, not very attractive, access to the beach can be difficult. |
|
|
Term
|
Definition
strong wire baskets, filled with stones that eventually get covered with grass and sand
Advantages - trap sand and often become covered in vegetation, visually less obstructive
Disadvantages - not as effective as a sea wall, shorter life span if exposed |
|
|
Term
|
Definition
a sloping concrete wall that is laid like a carpt along the coast
Advantages - beach scouring is less than a sea wall, relatively cheap form of (hard) defense, less intrusive than a sea wall
Disadvantages - unsuitable for high energy conditions, short life span |
|
|
Term
|
Definition
jumble barrier of large or irregular shaped concrete
Advantages - very efficient, relatively cheap
Disadvantages - cost rises if rock is imported, rocks must be large enough to remain stable, difficult to access beach, dangerous to young children |
|
|
Term
| describe beach redevelopment |
|
Definition
| the beach is made hicher and wider by seeding sand and shingle brought in by trucks or dredgers. Often used to protect (hard) defenses. |
|
|
Term
| describe an offshore breakwater |
|
Definition
located in the sea below the water mark. may be dumped interlocking material or concrete wall and protects shore from all waves.
Advantages - protects the shore from all waves
Disadvantages - difficult to access the beach from the ocean |
|
|
Term
| what are the 3 reasons that coasts need to be defended? |
|
Definition
some human activities are under threat from coastal erosion
Preserve the coast for heritage or conservation reasons.
Protect them from over development. |
|
|
Term
| what are the 4 planning options? |
|
Definition
do nothing - allow natural erosion to continue
Prevent and discourage
Managed retreat
Build defenses |
|
|
