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12.10: Longshore Currents and Longshore Drift

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    10341
    • Contributed by Miracosta Oceanography 101
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    Longshore Currents and Longshore Drift

    A longshore current is a current that flows parallel to the shore within the zone of breaking waves. Longshore currents develop when waves approach a beach at an angle (Figure 12.37). Longshore currents cause sediment transport called longshore drift. Longshore drift is the movement of sediments along a coast by waves that approach at an angle to the shore but then the swash recedes directly away from it. The water in a longshore current flows up onto the beach, and then back into the ocean in a “sheet-like” formation. As this sheet of water moves on and off the beach, it can transport beach sediment back out to sea. Objects floating in the longshore current move in a zigzag pattern up and down the beach as it moves down current.

    Longshore current and longshore drift
    Figure 12.37. Longshore currents and longshore drift are caused by waves approaching the beach at an oblique angle.