Coastal Defences Flashcards
Describe hard engineering
Uses man made structures to reduce or halt erosion
Highly effective
High cost
Have significant environmental impact due to use of concrete
Describe soft engineering
Uses more natural materials to reduce erosion
Aims to complement physical environment
Describe managed retreat
Allows erosion rates to carry on unchanged
Rate of erosion monitored and ways of adapting to this erosion are put in place
Factors affecting management strategies
- economy
= jobs, industry, insurance - social
= is coast historic, is it a home or village - environmental
= endangered species, nature reserves at risk, farms at risk
List soft engineering strategies
Dune stabilisation
Beach nourishment
Describe fine stabilisation
Marram grass planted
= roots help bind the dunes the protect land behind
= fences can be put in place to catch wind too
Advantages and disadvantages of dune stabilisation
- cost effective
- creates an important wildlife habitat
- cheap
- minimal impact of natural environment
- planting is time consuming
- can easily be damaged in a storm
Describe beach nourishment
Sand is added to the beach to replace material lost through erosion and transportation
Advantages and disadvantages of beach nourishment
- maintains the beach which is a major tourist attraction
- blends in with rest of beach so it isn’t unattractive
- large quantities of sand needed on a regular basis
- must transport sand regularly
Hard engineering strategies
Groynes
Sea walls
Rock armour
Revetments
Describe groynes
- wooden fences built down beach at right angles to coastline
- stop material moving down beach by longshore drift
- work by building up amount of sand on updrift side
= create wider beach
= increase tourists and economy
Advantages and disadvantages groynes
- builds up beach protecting cliff and increasing tourist potential
- cost effective
- visually unappealing
- deprives areas downwind of sediment increasing erosion elsewhere
Describe sea walls
- protect coast using concrete, steel or stone
- protect cliffs from erosion and act as barrier to prevent flooding
- deflect wave energy back to sea
= give people sense of security
Adv of dis of sea walls
- effective erosion prevention
- promenade has tourism benefits
- visually unappealing
- expensive to construct and maintain
- wave energy reflected elsewhere with impacts on erosion rates
Describe rock armour
- consists of massive blocks of natural rock piled up at base of cliff
- rocks dumped on top of each other
= leaving gaps to let water through - disperses energy of waves and reduces their erosion alr power
- quick to build and easy to maintain
Adv and dis of rock armour
- cost effective
- rocks are sources from elsewhere so don’t fit with local geology
- pose a hazard if climbed upon
Describe revetments
Wooden or concrete ramps that help absorb wave energy
Adv and dis of revetments
- cost effective
- visually unappealing
- can need constant maintenance which creates additional cost
Describe gabions
- wire cages filled with rocks that can be built up to support cliff
- often structured using local pebbles
- cheap to produce
- last 20/25 years
- can improve drainage cliffs
