LONGSHORE DRIFT Meaning and
Definition
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Longshore drift refers to the process of sediment transportation along a coastline. It is the movement of sand, gravel, and other particles parallel to the shoreline due to the combined action of waves, tide, and currents. This process plays a significant role in shaping the land and influencing coastal erosion and deposition.
The primary driving force behind longshore drift is the wave action. As waves approach the shoreline at an angle, their energy causes the particles on the beach to be pushed in the same direction as the prevailing wave direction. When the waves break, the swash carries the sediment up the beach, while the backwash pulls it back down. This continual cycle leads to a net movement of sediment along the coast.
The direction of longshore drift is often influenced by the prevailing wind direction, which determines the predominant wave approach. In areas where the coastline is sheltered or features natural barriers, such as headlands or groynes, the sediment may accumulate, resulting in the formation of spits, barrier islands, or sandbars. Conversely, erosion can occur in areas where sediment supply is limited or interrupted by human activities.
Longshore drift is a critical process in coastal engineering and management. Understanding its dynamics is essential for planning and designing coastal structures, such as breakwaters or sea walls, to mitigate erosion. It is also vital for assessing the vulnerability of coastal communities and ecosystems to changes in sediment movement and sea level rise induced by climate change.
Etymology of LONGSHORE DRIFT
The word "longshore drift" is a compound term consisting of "longshore" and "drift".
The term "longshore" refers to the direction or parallel to the shoreline, denoting the movement, transportation, or deposition of materials along the coast. This word comes from the combination of "long" (meaning extending over a great distance) and "shore" (referring to the area of land alongside a body of water).
The term "drift" in this context refers to the action of moving or being carried along by currents, winds, or forces. It comes from the Old English word "drift" which means to drive or carry.
Therefore, "longshore drift" is the transportation and movement of sediments or materials along the shoreline, driven by the currents or waves that act parallel to the coast.
