Coastal Water Movement  Most waves are created by wind.  The size & energy of a wave is influenced by:  How long the wind has been blowing  The strength of the wind  How far the wave has travelled across the ocean (called the fetch)  The power of waves is one of the most significant forces of coastal change

Coastal Water Movement  Waves arrive at the coast at an angle  As the waves enter shallow water they begin to slow down as the bottom of the wave drags on the shallow ocean bottom

Coastal Water Movement  The breaking waves send water onto the beach at an angle (called swash), however the water goes straight back out to sea (called backwash).

Longshore Current  These waves coming in at an angle cause a current, called the longshore current, to flow parallel to the shore in the surf zone.

Coastal Water Movement  The size of a wave and the angle at which it strikes the beach determine the amount of sand moved Longshore drift: The movement of sand down the beach by wave action (swash and backwash)

Coastal Water Movement  As water becomes calmer, sand settles to the bottom. KEEP CALM AND DEPOSIT SAND

Rip Currents  A Rip Current is a strong, narrow current of water that runs perpendicular to the beach, out into the ocean  Rip currents do NOT pull people under water, they carry people away from shore  Rip current is the correct term to use – NOT undertow or riptide

Rip Currents

A channel forms in the break between sand bars

Formation of Rip Currents

How to Identify Rip Currents Look for these clues:  Channel of churning, choppy water  Area with noticeable difference in water color

How to Identify Rip Currents More clues:  A line of foam, seaweed, or debris moving steadily seaward  A break in the incoming wave pattern

Rip Currents Rip Current Video Clip – uqYhttp:// uqY