What does a longshore current do to sand?

As a coastal geomorphologist with expertise in the study of coastal processes, I can explain the impact of longshore currents on sand. Longshore currents play a significant role in shaping the coastline by influencing the movement of sand along the shore. Here's how they affect the sand: 1. Erosion and Deposition: When a longshore current moves along the coast, it can cause erosion on one part of the beach and deposition on another. The current can strip sand from certain areas, particularly during storms when wave energy is high. 2. Beach Features: These currents contribute to the formation of various coastal features such as spits, bars, and tombolos. For example, sand deposition can lead to the formation of a sandbar offshore or a spit extending from the shore. 3. Coastal Protection: In some cases, longshore currents can help protect the coast by redistributing sand, which can help maintain the width of the beach and reduce the impact of wave erosion on the coastline. 4. Sediment Transport: Longshore currents are a major mechanism for the lateral transport of sediment along the coast. They can move vast amounts of sand over time, leading to changes in the shape of the beach and the coastline. 5. Human Impacts: Human activities such as the construction of coastal defenses or the removal of sand for construction purposes can disrupt the natural flow of longshore currents, leading to adverse effects on the coastal environment. In summary, longshore currents are a dynamic force in coastal geomorphology, significantly affecting the distribution and movement of sand along the shore.

A longshore current is an ocean current that moves parallel to shore. It is caused by large swells sweeping into the shoreline at an angle and pushing water down the length of the beach in one direction.