A beach is a narrow strip of land that lies along the edge of a body of water, such as an ocean or lake. It is made of materials such as sand, pebbles, and rocks, which are formed by erosion over time. Some beaches are rocky, while others have gentle slopes covered with sand and seashell fragments. Beaches have a wide variety of uses, including recreation and tourism. Beaches are often populated by animals such as crabs, birds, and sea turtles. Sea grasses and other plants also grow on some beaches. Many beaches are lined with buildings and other structures, such as lifeguard stands and shacks. Beaches are often popular for recreational activities, such as sunbathing, swimming, and surfing.
The characteristics of a beach depend on the nature and quantity of the sediments, their state of compaction, the speed and turbidity of wind and wave action, and the availability of freshwater. Sediments that have been compacted by the action of waves or by water that percolates through them are more resistant to erosion than uncompacted sediments. Beaches are usually sandy, but can also be muddy or made of gravel.
Beach erosion is a result of the natural process of waves pounding a coastline, but also is affected by human activity. For example, the destruction of a coral reef offshore can change the shape of the coast, and in turn affect the beach. In addition, people can remove beach vegetation and dig up sand to use for construction or other purposes. This can increase erosion by removing the material that prevents sand from moving inland.
One of the most important ways to protect a beach is to reduce pollution, which can include debris and trash that is washed ashore or left behind by humans. Plastic can harm wildlife, especially sea lions and other marine mammals that become tangled in it. In addition, the presence of trash can deprive sea anemones and other algae and plants that live in tide pools of nutrients they need to grow.
Other natural processes that contribute to beach erosion include long shore drift, which is the movement of sediments down the shoreline. This is caused by the combined action of ocean currents, wind direction, tidal movements, and oblique wave action on the shore.
Other factors that can influence beach erosion include the amount of freshwater available, whether it is available in the vicinity of a beach, and the availability of food to coastal plants and animals. For example, if freshwater runoff is diverted into drains near the beach head, this can deprive coastal plants of their freshwater supply and expose them to increased erosion by salty sea water. In addition, the loss of natural beach vegetation can also reduce the ability of beach soils to resist erosion by wave action. A technique known as beach nourishment can be used to replenish a beach that has been reduced by erosion. Beach nourishment involves importing and depositing sand to restore the beach.