L8 - Lyme Regis Management Flashcards
What are the advantages and disadvantages of rock armour?
advantages:
- relatively cheap
disadvantages:
- environmentally ugly
- rests on sand / shingle - undermined
What is advancing the line out to sea?
building new defences out to sea and reclaiming the land between the defences and the current coastline for development
What is a shore line management plan (SMP)?
a detailed plan produced by the Environment Agency for how to manage the coastline in an area
what are the advantages and disadvantages of groynes?
advantages:
- stops long shore drift and keeps beaches in place
disadvantages:
- starves down coast, increasing erosion there
What are the advantages and disadvantages of sea walls?
advantages:
- stops erosion, but less sediment down coast
- energy is reflected (not absorbed)
disadvantages:
- expensive to build (£1m/km)
- waves scour base, undermining, collapsing
what are groynes?
wooden, rock, or concrete structures built perpendicular to the shoreline that act to trap material that would have been transported by long shore drift
what does it mean to do nothing?
allowing nature to take its course, not interfering or managing the retreat of the coastline
what is a cost benefit analysis (CBA)?
a comparison of social, economic and environmental cost with the costs of building defences
what is managed retreat?
the shoreline is allowed to retreat but actions are taken to minimise the impact such as compensation for land owners.
Advantages:
- encourages development of beaches ( a natural defence ) and salad marshes ( important for environment )
- can provide sediment to build up beaches in areas of higher land value
what is holding the line?
maintaining the position of the current shoreline by building sea defences
what are sea walls?
large concrete structures built at the back of a beach, often with a curved top to reflect wave energy back out to sea
what is slope stabilisations?
a useful soft engineering strategy to employ on cliffs that are prone to mass movement processes
what is soft engineering?
less expressive than hard engineering options, usually more long-term and sustainable with less impact on the environment, to be to be less effective in holding the line
what is beach replenishment?
artificially adding to the amount of material (e.g. sand and shingle) on a beach to protect the back of the beach or cliff face from wave attack
what is hard engineering?
coastal management options that tend to be expensive and need maintenance. typically associated with a ‘hold the line’ approach. may also have a high impact on the landscape or environment as they involve the construction of substantial sea defences.
