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Beaches as a Coastal DefenceThe whole of the Sefton Coast is fronted by a sediment foreshore generally dominated by sand except in the most northern reaches where silty sediments predominate. These beaches vary in width from approx 500 metres at Waterloo to approx 5 kilometres at Marshside. The beaches and their adjacent nearshore zones buffer the wave energy coming from offshore. Sefton's beaches cover approximately 40,000,000m2 and contains approximately 260,000,000m3 of sediments above the -5m AOD contour.The width and gradient of the beach affect the amount of energy reaching the top of the beach from the waves. Generally a wider, gently sloping beach will have less energy reaching the top of the beach than a narrow, steep beach. However, the shape of the beach is affected by the waves, tides, currents, wind, sediment supply and the nearshore conditions. Monitoring changes in the beach can assist in predicting coastal erosion, marine flooding, accretion and other processes. Changes can be deteced in beach height, beach width and sediment composition which can indicate the changes that are occuring in the energy flows of the coastal processes.
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