Erosion of Shorelines Essay -- Nature Environment Papers

Erosion of Shorelines The erosion of shorelines is a natural process that can have beneficial or adverse impacts on the creation and maintenance of habitats. Sands and gravels eroded from the shores of coastal bays maintain the beach as a natural barrier between the open water and coastal wetlands. Beaches move back and forth onshore, offshore and along shore with changing wave conditions. The finer-grained silts and clays derived from the erosion of shorelines are sorted and carried as far as the waters of wetlands or tidal flats, where benefits are derived from addition of the new material. However, excessively high sediment loads can smother submerged aquatic vegetation beds, cover shellfish beds and tidal flats, fill in riffle pools, and contribute to increased levels of turbidity and nutrients (http://www.epa.gov/OWOW/NPS/MMGI/Chapter6/ch6-4.html). Longshore drift is the movement of sand parallel to the shoreline, in the â€Å"along-the-shore† direction (H. Nepf). Longshore drift is caused by the water waves breaking against the shore. As the waves break, they thrust water forward, creating movement of water in the direction the wave is traveling. If a wave approaches a beach at an angle, the forward rush of water is directed partially parallel and partially perpendicular to the shore. The parallel component of motion creates the longshore current, a steady movement of water parallel to the shoreline, that carries sand and contributes to the longshore drift. The longshore current is confined to the region where the waves break, called the surf zone (the frothy, white water created by the breaking waves). In regions of strong wave activity the longshore drift steadily carries sand away, eroding the coast. In... ...tions are poor or where little penetration is possible, a gravity-type structure such as a stone revetment may be preferable. However, all vertical protective structures (revetments, seawalls and bulkheads) built on sites with soft or unconsolidated bottom materials can experience scouring as incoming waves are reflected off the structures (http://www.epa.gov/OWOW/NPS/MMGI/Chapter6/ch6-4.html). Shoreline erosion is a problem widely attributed to by commercial and residential development. Many methods can be used to prevent erosion and promote sand accumulation. However, most man-made structures are simply made to protect buildings and surrounding land, not the entire beach. Some believe beachfront homeowners should move their houses or simply move. Whatever the decision, erosion is a natural process and will continue whether a house exists in its path or not.