Coastal management

Coastal management

1. Hard engineering

   • Heysham and Morecambe
     • Rock armour/rip rap to enhance and protect the existing sea wall- Boulders of locally sourced limestone were placed along the majority of the existing promenade and sea walls from the western end of the promenade to about one kilometre east of the town centre. In total 436,000 tonnes of rock armour was installed
     • Breakwaters or rock groynes- Around ten breakwaters and rock groynes were built at intervals in front of the worn. Just under a million tonnes of locally sourced limestone boulders were used
     • Gabions- Over 500 cages, measuring 2x1x1m, filled with small limestone boulders were used in various locations to reinforce the coast
     • Traditional recurved sea wall along the prom. A project of further improvements and repair begun in 2015
     • Concrete revetment and sea wall- To the west of Heysham Head, extending to the port and power station, the existing sea wall and large concrete revetments were repaired and left in place
     • As well as encouraging beach formation between the breakwaters, 89,000 tonnes of sand and 19,000 tonnes of shingle were used for beach nourishment
   • Making physical changes to the landscape, using resistant materials, like boulders, wood and metal. It interferes or stops the natural processes
   • Sea walls- Aim to dissipate wave energy. The recurve structure throws waves back out to sea, into the path of the next incoming wave, thus also reducing its wave impact. They also provide a physical barrier to flooding by raising the height of the coastline
   • Rock armour (rip-rap)- Consists of large boulders dumped in front of a cliff or sea wall to take the full force of the wave. They are left angular in appearance to present a large surface area to the waves, and create gaps for water to filter through. The boulders are not secure so they take energy out of the wave by rocking
   • Gabions- Small boulders are contained within steel wire-mesh cages, each of which can be joined together to form larger structures, or walls
   • Revetments- Concrete or wooden structures placed across a beach to take the full force of the wave energy, preventing further erosion of the coast
   • Groynes- Wooden, stone or steel breakwaters built nearly at right angels to the waves. They control longshore drift by trapping sediment to create a wider beach which will then dissipate wave energy. They may have serious effects down the coast
   • Cliff fixing- Done by driving iron bars into the cliff face, both to stabilise it and to absorb some wave power
   • Offshore reefs- Force the waves to break offshore, which reduces their impact on the base of cliffs
   • Barrages- Large structures built to prevent flooding on major estuaries and other large sea inlets. A barrage acts as a dam across an estuary and prevents incursion of seawater. A good example is those that are part of the Delta Plan in the Netherlands and the Cardiff Bay barrage in Wales which was completed in 1999
   • Hard engineering strategies are generally long lasting and effective over their planned lifespan. However, they are expensive to build and maintain (to repair a sea wall ca cost over £5,000/m), defence in one place can have serious consequences for another area of the coast and structures are sometimes an eyesore, spoiling the landscape and physically disrupting natural habitats

2. Soft engineering

   • Formby Point on the Sefton Coast
     • 'Planting' used Christmas trees on the seaward edge of the dunes to trap more sand and encourage dune regeneration
     • Fencing off areas of sand dunes to restrict pedestrian access
     • Wooden posts placed in front of the dunes to encourage dune regeneration
     • Building boardwalks to stop people trampling on the dunes
     • Signage to direct people to the beach via routes avoiding the dunes
     • Ranger services to educate local children about the protection and conservation of dunes
     • Controlling the extraction of sand for commercial purposes
     • Banning off-road vehicles from the dune system
   • Using natural systems for defence such as beaches, dunes and salt marshes which can absorb energy. It tends to work with the natural processes
   • Beach nourishment- This is the attempt to replace material that has been lost through longshore drift
   • Dune regeneration- Includes replanting vulnerable areas with plants such as marram grass and stabilising the surface with sacking or wire mesh, selective grazing, afforestation with quick-growing conifers, restricting access by fencing off areas, providing boardwalks for tourists and giving tourists information about potential damage
   • Managed retreat- This involves abandoning the current line of sea defects and then developing the exposed land in some way, perhaps with salt marshes, to reduce wave power. If old sea defences such as walls are abandoned, low-lying land will be flooded and reclaimed naturally by marsh plants which act as a defence against rising sea levels
   • Land-use management- Involves addressing people's behaviour and educating the local community. E.g. caravan parks on cliff tops can be moved and re-sited quickly. Giving land at risk of flooding over to grazing rather than growing crops means the sheep of cattle can be moved if storms are forecast
   • Do nothing- Tens of millions of pounds are spent annually in the UK on coastal protection and it might be cheaper to let nature take its course and pay compensation to those affected. Some argue that the limited funds available for coastal protection should be targeted to places that have significant infrastructural or economic value for large numbers of people

3. Sustainable approaches to coastal management

   • Shoreline management plan
     • Developed by coastal groups with members mainly from local councils and the Environment Agency
     • They identified the most sustainable approach to managing the flood and coastal erosion risks to the coastline in the: short-term (0-20 years), medium term (20-50 years) and long-term (50-100 years)
     • Introduced in 1995, there are 22 SMPs around the UK coastline. A most short-term plans are near completion many now have a second generation plan
     • Introduced to avoid piecemeal approach to coastal management
   • Integrated coastal zone management
     • A set of principles to guide planning on the whole coastal zone
     • It looks at the environmental, social and economic development at the coast
     • Idea constructed at Rio Earth Summit in 1992 (Agenda 21)

4. Sea level change

   • It is very likely that sea level will rise in more than about 95% of the ocean area
   • About 70% of the coastlines worldwide are projected to experience sea level change within 20% of the the global mean sea level
   • Global sea level rise during 1901-2010 can be accounted for by ocean thermal expansion, ice loss by glaciers and ice sheets, and change in liquid water storage on land
   • Major road and rail networks are at risk and many nuclear power plants are on low lying land
   • Water supplies could be contaminated as water used for human consumption may now be affected by salt water
   • Further abroad, the Maldives very existence is under threat as the result of sea level change. The highest point of the Maldives is only 8m above sea level