Hard engineering involves building artificial structures which try to control natural processes.
Hard engineering approaches to coastal management tend to be expensive, last only a short amount of time, are visually unattractive and unsustainable. They often increase erosion in other places further down the coast.
The image below shows a range of hard engineering strategies at Hornsea, Holderness Coast.
Sea defences at Hornsea
Groynes are wooden barriers constructed at right angles to the beach to retain material. The material is trapped between these groynes and cannot be transported away by longshore drift. Groynes encourage a wide beach which helps absorb energy from waves, reducing the rate of cliff erosion. The image below illustrates the difference in how far waves travel inland when sediment is trapped by a groyne raising the height of the beach.
A groyne at Hornsea on the Holderness Coast
Cheap, retain wide sandy beaches and do not affect access to the beach.
Beaches beyond the defences are starved of beach material due to their impact on longshore drift.
Typically around £7000 each
Seawalls are usually built along the front of cliffs to protect settlements or another land of high economic importance. They are often recurved which means waves are reflected back on themselves. This can cause the erosion of material at the base of the seawall.
Recurved sea wall and rock armour at Scarborough
The video below shows the sea wall at Scarborough.
Provide excellent defence where wave energy is high, reassures the public and long lifespan.
They are expensive and can affect beach access, recurved sea walls can increase the erosion of beach material.
Traditionally these have been wooden slatted barriers constructed towards the rear of beaches to protect the base of cliffs. Energy from waves is dissipated by them breaking against the revetments. In recent times concrete revetments such as accropodes have been used in places such as Scarborough.
Less beach material is eroded compared to a seawall. Cheaper and less intrusive than a sea wall.
Short lifespan and unsuitable where wave energy is high.
These are often large boulders placed along the base of a cliff to absorb energy from waves.
Cheap and efficient at reducing energy in waves that approaching the coast.
Unattractive, dangerous access to the beach, costs increase when the rock is imported.
This is where rocks and boulders are encased in a wired mesh. They absorb the energy from waves.
The image below shows a gabion.
Coastal erosion defences in the form of interlocking concrete blocks in the foreground and stone-filled wired gabion baskets behind
Cheap and efficient.
Shorter lifespan than a sea wall. Visually unattractive.
£100 per metre.
These are large concrete blocks and boulders located offshore to change the direction of waves and reduce longshore drift. They also help absorb wave energy.
Beaches retain a natural appearance.
Difficult to maintain, unattractive, does not protect the cliffs directly and does not stop beach material from being eroded.
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