A beach is a landform that is adjacent to a body of water. Beaches are primarily sandy but may also be gravelly, pebbly or rocky. They often have dunes and sometimes vegetation (such as seaweed) and are characterized by the presence of water and the ebbing and flowing of waves. Beaches are not just found in the ocean; they can be near lakes or alongside rivers. Beaches can be natural or constructed through human activities like beach nourishment.
Beach erosion is a constant process that slowly carries sediments from the shoreline to the deep water. The type of sediment that composes a beach may vary, but in general, the finer sandy particles are washed inland by wave action and become part of a river system while the coarser grains are carried offshore in longshore drift. Beaches are formed in a wide range of landscapes from rocky coastal features to delta-shaped rocky beaches. The composition of a beach is also influenced by the underlying geology, and in some cases, the location of a beach within a coastline can be determined by its proximity to a submarine canyon or river mouth.
Changing the size and shape of a beach is not easy. A beach can be enlarged through construction and beach nourishment, but the new material must be able to settle and compact before it can withstand aggressive wave or wind action. If not sufficiently stabilized, the new sediments can be eroded or deposited elsewhere in a landscape, forming a bar.
Sandbars are narrow areas of sand and sediment just offshore of a beach. They form when turbulence in the water of a breaking wave forms a trough that reaches back into the sandy bottom. As the wave retreats, a longshore current moves sand particles forward and off of a beach, depositing them at the rear of the trough. Occasionally, energetic incident waves can generate enough energy to reach the intertidal area of a beach and induce regular wave breaking and associated sand transport. This causes the outer bar to decay and a new one to form at its location offshore.
Many beaches are highly polluted by bacteria, raw sewage and other waste materials that wash up on the shore. This pollution is caused by storms and the movement of waste water from inland by rivers, drain pipes and sewer systems. In addition to this organic debris, some beaches are littered with plastics, glass and other man-made waste. This is an issue that is being addressed by various environmental organizations and local governments through beach cleanup programs. They are trying to educate the public and encourage people to clean up after themselves when they visit beaches. They are also working to implement policies that protect and preserve beaches. These include limiting the amount of construction that can take place in or around the shoreline, and encouraging beachgoers to use eco-friendly products when washing off the sand. They are also promoting the planting of trees that are adapted to the salt environment, such as coconut palms.