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# Longshore Currents

## Currents Tutorial

The speed at which waves approach the shore depends on sea floor and  shoreline features and the depth of the water. As a wave moves toward  the beach, different segments of the wave encounter the beach before  others, which slows these segments down. As a result, the wave tends to  bend and conform to the general shape of the coastline. Also, waves do  not typically reach the beach perfectly parallel to the shoreline.  Rather, they arrive at a slight angle, called the “angle of wave  approach.”

When a wave reaches a beach or coastline, it releases a burst of energy  that generates a current, which runs parallel to the shoreline. This  type of current is called a “longshore current.”

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Longshore currents are affected by the velocity and angle of a wave.  When a wave breaks at a more acute (steep) angle on a beach, encounters  a steeper beach slope, or is very high, longshore currents increase in  velocity. Conversely, a wider breaking angle, gentler beach slope, and  lower wave height slows a longshore current’s velocity. In either case,  the water in a longshore current flows up onto the beach, and back into  the ocean, as it moves in a “sheet” formation.

As this sheet of water moves on and off the beach, it can “capture” and  transport beach sediment back out to sea. This process, known as  “longshore drift,” can cause significant beach erosion.

### Currents Lessons

              - Welcome
              - Tidal Currents 1
              - Tidal Currents 2
              Coastal Currents
              - Waves
              - Longshore Currents
              - Rip Currents
              - Upwelling
              Surface Ocean Currents
              - The Coriolis Effect
              - Surface Ocean Currents
              - Boundary Currents
              - The Ekman Spiral
              The Global Conveyor Belt
              - Thermohaline Circulation
              - The Global Conveyor Belt
              - Effects of Climate Change
              How Are Currents Measured?
              - Age of Exploration
              - What is a "knot"?
              - Shallow Water Drifter
              - Deep Ocean Drifter
              - Current Profiler
              - Shore-based Current Meters
              - How Currents Affect Our Lives?
              - References
              - Roadmap to Resources
              - Subject Review

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