A beach is a place where sand, gravel, cobbles, pebbles, and other granular material accumulates during periods of accretion and moves away during periods of erosion. Though we tend to think of beaches only by the sea, they can also be found next to lakes and large rivers. The size, shape, and composition of a beach depend on geological and oceanographic factors.
Beach morphology is the study of how a beach changes over time. Beach accretion and erosion are controlled by wave energy, tidal range, and the direction and speed of currents. Beach erosion is further influenced by the amount of sediment available and how quickly the water flows. Beaches are a complex ecosystem that supports many different species of plants and animals. These ecosystems provide valuable ecological services, including shoreline stabilization, water filtration, and carbon sequestration. Beaches are also popular recreational and tourism destinations.
A beach can be made up of any number of materials, including sand, gravel, cobbles, and even shells. The sand that forms the beach is either geological (formed by weathering of rocks) or biological (derived from the breakdown of coral skeletons and other shells from marine organisms). Beaches are constantly changing, with new sediment arriving at a beach from offshore during a storm and moving out again at low tide. Beaches are shaped by the size of waves and currents, and they can be narrow or wide, flat or steep, and long or short.
The main part of a beach that is above the normal high tide line is called the beach berm. This ridge of sand is often dry and gets wet only during very high storm surges or very high tides. Beach berms are typically formed from an offshore bar that moved ashore during a storm and slowly, over the course of weeks or months, migrated up onto the beach.
Sand dunes are often located behind the berm. These dunes can be quite tall, reaching a toto sgp height of over 20 meters (65.6 feet). Beach dune systems are important for protecting the beach from wind and waves and providing habitat for plants and animals that live in these areas.
A beach is home to a vast array of plants and animals that are specially adapted to these challenging environments. These include microscopic algae, bacteria, mollusks, and crustaceans that live buried in the sand, and sea turtles and shorebirds that use them for nesting and feeding. Beaches are also popular recreational and tourist destinations, supporting a variety of businesses like food service, watersports, and lodging. These uses of a beach can have a negative impact on the ecosystem, however. Waste from people at a beach can contribute to water pollution, especially when the beach is close to sewage and other drainage pipes. In addition, boats and their passengers can leave a lot of trash on the beach, and this can be dangerous to wildlife. Coastal management practices are designed to prevent these negative impacts and promote the sustainable use of beaches.