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Hard Engineering - Coggle Diagram
Hard Engineering
Gabion
Benefits
Economic
At £110 a metre, they are relatively cheap and easy to construct. Gabions are often constructed on site using local pebbles. This makes them much cheaper than sea walls, rock armour or groynes. It also makes them ideal as a quick-fix solution. For the cost, they are good value for money, as they may last 20-25 years.
Environmental
They blend in better than other hard engineering methods, especially when sand is blown into them or when they are covered by vegetation.
Costs
Environmental
Damaged gabions are unsightly and sea birds may damage their feet in them.
Social
In a damaged state, gabions are dangerous. People may trip over them or cut themselves on the broken steel wire mesh
Economic
The use of gabions is restricted to sandy beaches, as shingle hurled at them would quickly degrade them. Gabions are easily destroyed, so regular maintenance is needed. Repair c embedded, vegetation-covered gabions can be expensive.
Groynes
Benefits
Economic
At £5,000 each, groynes are relatively cheap and, if well maintained, can last up to 40 years. A larger beach, with more space for activities, attracts more tourists, which boosts the local economy.
Social
Rock groynes at Sandbanks, Poole, have concrete crests for people to walk along to reach a viewing or fishing point. Groynes also act as windbreaks
Costs
Social
Groynes are barriers, which impede walking along a beach. They are also dangerous, as they have deep water on one side and shallow water on the other. This is a particular hazard to children who find it hard to resist climbing on them
Environmental
Groynes may be considered unattractive, especially degraded ones.
Economic
By trapping sediment, groynes restrict the supply of sediment down-drift. For example, the new groynes at Poole restrict sediment movement towards Bournemouth. The problem is merely passed on to incur more cost.
Rock Armour
Costs
Environmental
Rock armour is ugly and it often covers vast areas of a beach. Driftwood and litter become trapped in the structure and imported rocks do not blend in with the local geology.
Social
Rock armour makes access to the beach difficult, as people have to clamber over it or make long detours. People may have accidents when clambering over it as rocks may be unstable and, if rocks are regularly covered by the tide, they may collect slippery seaweed, which accentuates the hazard
Economic
Highly resistant rocks from Norway and Sweden are often used in preference to rocks from local quarries. This may cause resentment and it inflates the cost considerably.
Benefits
Economic
Rock armour costs £1000-3000 a metre, compared to £5,000 a metre for a sea wall. The structure is quick to build and easy to maintain. It can be built in weeks rather than the months it takes to make a sea wall. If well maintained, rock armour lasts a long time.
Sea Wall
Benefits
Social
A sea wall gives people a sense of security. It often has a promenade on top of it, which doubles up as a cycle route outside peak walking periods. Steps at the base of a wall act as seating areas for beach users
Economic
If well maintained, sea walls can last for many years
Environmental
Sea walls do not impede the movement of sediment downdrift, so they do not disadvantage other areas.
Costs
Social
They restrict people's access to the beach and if waves break over the sea wall (overtopping), coastal flooding may occur
Economic
sea walls are expensive to build. Repairs are also expensive. Reflected waves scour the beach in front of a sea wall and this undermines its foundations. If damage is not repaired quickly, the result may be devastating
Environmental
From the beach, a wall of concrete is ugly to look at. Sea walls can also destroy habitats. .