Our coast is shaped by many forces - the sea, the wind, the structure of the rock and earth along different parts of the coast, and even people and their activities. Coastal landscapes are formed by a combination of erosion, transportation and deposition processes.
Coastal erosion is a complex natural process, where waves wear away and break up the edge of the land along the coast. The stronger the wave the more erosion it will cause. Waves are created by wind blowing over the surface of the sea.
The size of a wave depends on:
When a wave breaks, water is washed up the beach - this is called the swash. The water then runs back down the beach - this is called the backwash. The strength of the swash and backwash determines the type of wave created. There are two types of waves - constructive and destructive waves.
Constructive waves break on the shore and deposit material, building up beaches. They occur when the swash is stronger than the backwash.
Destructive waves are created in storm conditions. They are created from large, powerful waves when the wind is strong and has been blowing for a long time. These waves occur when the backwash is stronger than the swash, the waves are said to be destructive.
Destructive waves erode the coastline to create our beaches, bays and harbours in four ways:
Coastal erosion becomes a hazard where people's homes, properties, road or services are threatened by loss of land.
Inundation is the flooding of coastal areas during storms. The flooding results from a combination of sea storms and high tides, which will drive high, strong waves onshore onto normally dry, but low lying coastal land.
Sea water can damage homes, property and even contaminate coastal aquifer water supplies.
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