A beach is a coastal landform consisting of sand or other coarse sediment. It is usually characterized by dunes and may have a trough, longshore currents, surf zones, backwash, rip currents and depressions between adjacent intertidal bars (beach ridges). Beaches often vary from one to the next due to differences in wave energy or the presence of vegetation. A beach is also the location of tide pools, and can be a natural habitat for flora and fauna. Beaches can be very clean or very polluted depending on the nature of runoff from inland areas and human activities. Beach pollution includes garbage (such as plastic bags, cans and containers from picnics), raw sewage or other toxic chemicals that are carried by rainwater through drainage pipes or from inland rivers, and human waste such as urine, feces and medical waste.
A beach changes with the seasons. In temperate regions, summer is characterized by calmer seas with longer periods between breaking waves and the gradual filling of beaches with fine sediments transported up the beach by longshore currents. In contrast, winter is characterized by more energetic waves with rapid erosion.
The color of a beach depends on the type of sand. Sands derived from metamorphic rock such as limestone or granite tend to be light-colored, whereas those from volcanic islands are jet-black because they contain olivine. The color of a beach can also be affected by the type and extent of vegetative cover. Dense natural vegetation tends to absorb rainfall reducing the speed and erosive power of runoff that carries silt and organic material from upland areas to the beach. Destruction or disturbance of this vegetation causes faster runoff, which deposits more silt and organic material on the beach and in the ocean.
The condition of a beach can be improved by “beach nourishment.” This is the process of pumping sand onto the shore to improve its health. This is a common practice in many major cities around the world and, because of its natural appearance, most people are unaware that their favorite beach has been artificially “nourished.” The beach nourishment industry is booming as people seek healthier and more attractive beaches. This process can also be used to restore eroded coastlines. For example, the sand was pumped into Waikiki Beach during the 20th century to combat beach erosion caused by waves and wind. A similar project is now underway to replenish a section of Florida’s famous Miami Beach. The sand will be brought in from Manhattan, California. Beach nourishment is not without controversy, however. Some people are opposed to it on the grounds that it destroys native marine species. Others object to the amount of money being spent on a project that could be better used for other purposes. Regardless of their views, it is important for everyone to respect the fragile environment of the beach and refrain from any behavior that might damage it. If enough people do this, the natural beauty of the beach will be preserved.