Marine aggregate is playing a front-line role in replenishing Britain’s beaches and protecting the coastline and coastal communities. Replenishment, or nourishment, of beaches is part of a move toward use of “soft” coastal defence management methods that negate the need for previously favoured “hard” defences such as sea walls, groynes and rock dumping that can prove detrimental to natural coastal processes. Over 38 million tonnes of marine sand and gravel has been used for this purpose since 1990, and with the growing threats posed by sea level rise and increased storminess, the use of marine sand and gravel for coast protection purposes is likely to become increasingly important.
Many ongoing coast defence projects which protect communities and key infrastructure assets are entirely dependent on the continuing availability of marine aggregate supplies – with there being no practical alternative for large scale beach nourishment. Large scale beach nourishment is only possible from marine sources, where large volumes landed direct from dredgers avoid the need for fleets of heavy lorries. In many cases, as well as protecting the coastline, the amenity value is also improved, thereby benefiting the local economy.
Major schemes have included the east coast between Mablethorpe and Skegness and between Happisburgh and Winterton. On the south coast, major replenishment schemes have taken place at Hythe, Eastbourne, Hurst Spit, Bournemouth and Weymouth. Dredgers typically anchor approximately 500 metres offshore and pump their cargoes to shore via a floating pipeline at a rate equivalent to one lorry load (20 tonnes) every 15 seconds. Alternatively, cargoes may be back-loaded into smaller barges to be taken to shore, or sprayed directly onto the beach by dredgers through a process termed ‘rainbowing’.