Year 11 Managing Coastlines Flashcards
What are sea walls
Provides barrier between waves and the land placed at back of beach
curved walls better than straight as reflect energy back out to sea.
steps often added at base to give stability
Benefits of sea walls
Provides sense of security, visual protection
Doesn’t affect longshore drift
Walkway can be added on top for leisure
Can last many years if maintained
Costs of sea walls
Restricts access to beach
Expensive to build and maintain
reflected waves can scour beach, undermining foundations leading to beach nourishment
Can look ugly and damage natural habitats
What are groynes
Wooden or stone structures built in foreshore built at right angles to beach
trap sediment moved by longshore drift, building up beach so can absorb wave energy and act as a buffer
What are the benefits of groynes
Larger ones can be used as mini piers for fishing etc.
Acts as windbreak
relatively cheap and long lasing if maintained
Can act as tourist attraction
What are the costs of groynes
Impede walking along the beach
Can make beach dangerous as create ares of deep and shallow water
restricts flow pf sediment downstream
Needs regular maintenance
What is rock armour (rip rap)
Made up of thousands of tonnes of hard rock (granite)
act as a barrier between sea and land
as waves break against them water enters gaps and energy is dispersed
What are the benefits of rock armour
Quick to build and easy to maintain so long lasting
versatile can be placed in front of sea walls to protect them or stabilise sand dunes
What are the costs of rock armour
Make access to beach difficult
can be expensive depending on distance travelled
ugly and need reguar maintenance
trap things in the rocks e.g. litter
What are gabions
Steel wire-mesh cages filled with pebbles or rocks
placed at back of sandy beaches creating a low wall structure
energy dispersed same as rip rap reducing rate of erosion
What are the benefits of gabions
Cheapest hard engineering method and easy to construct
last for 20-25 years
blends better with environment especially when sand and vegetation added
What is beach nourishment
Replacement of lost sediment from the beach
means fewer waves reach back of the beach so more energy dissipated by beach
can be completed through beach recharge (sand taken from bay and added to beach)
or completed by beach recycling (down drift sand moved up)
What are the benefits of beach nourishment
Wider beach means more room for beach users
wider beach means less need for sea wall maintenance as better protected
More natural and blends with environment
What are the costs of beach nourishment
During process access to beach restricted and hose living near donor beaches may be resentful
Although cheaper than hard engineering expensive to higher dredger
What is beach reprofiling
Artificial reshaping of beach using existing beach material
bulldozers move material back up beach after winter storms move it down to the foreshore creating buffer for wave energy
