Hard engineering management schemes

Hard engineering management schemes

1. Sea wall- A concrete rock wall, placed at the foot of cliffs or top of the beach. It usually has a curved face to reflect waves back into the sea

   • Cost £6000 per metre
   • Effective at stopping the sea
   • Often has a promenade for people to walk along
   • Can be intrusive and unnatural to look at
   • Expensive to build with high maintenance costs

2. Groynes- Timber or rock structures, built at right angles to the coast. They trap sediment being moved along the coast by longshore drift

   • Built up beaches increase tourism and gives greater protection to the land behind it
     • Works with natural processes
   • Cost £5000-£10000 each (at 200 metre intervals)
   • Not too expensive
   • Interrrupting longshore drift starves beaches along the coast from sediment
   • Unnatural and unattractive to look at

3. Rock armour- Consists of large, tough rocks dumped at the foot of a cliff, or the top of a beach. It forms a permeable barrier to the sea- breaking up waves, but allowing some water to pass through

   • Relatively cheap and easy to construct and maintain
   • Often used for fishing on and sunbathing by tourists
   • Cost £100000-£300000 for 100 metres
     • Dangerous for people clambering over them
   • Rocks are usually imported from abroad, so do not fit with the local geology
   • Can be very intrusive

4. Revetments- Wooden or rock barriers placed at the foot of a cliff or the top of the beach. They break the energy of waves

   • Relatively inexpensive
   • Cost up to £4500 per metre
   • Intrusive and very unnatural looking

5. Gabions- Wire cages filled with small rocks that can be built pup to create walls and are sometimes used support weak cliffs

   • Relatively inexpensive and flexible
   • Encourages upper beach stability
   • Look very unsightly to begin with
   • Metal cage can rust and become damaged
   • Cost £5000-50000 for 100 metres

6. Offshore breakwater- A partly submerged rock barrier designed yo break up waves before they reach the cost

   • Cost similar to rock armour
   • Effective permeable barrier
   • Visually unappealing
   • Potential navigation hazard

7. Barrages- Involve the construction of a partly submerged wall in a bay or estuary. Sluice gates control water flow. They are sometimes used to create tidal power

   • Offers multi-purpose use e.g. tidal power
   • Very expensive
   • Potentially dangerous to habitats
   • Cost £200 million (Cardiff Bay)