Washington's Coast
Washington State Department of Ecology



How sand is carried
along the beach

Waves come ashore diagonally, as their backwash flows perpendicular to the beach. Sediment particles travel in a zigzag path as they are moved along the beach. This motion creates a current that runs parallel to the beach. Storms can generate high waves that approach the shore at a larger angle, causing a faster current.

How sand is carried
along Washington's southwest coast

Summer: During the summer, winds come from the northwest; sand moves south.
Winter: During the winter, winds come from the southwest; sand moves north. Because winter winds blow harder, the dominant drift direction is north.
For several thousand years, floods washed sand to the mouth of the Columbia River, where it collected in shoals. Longshore currents shuttle sand from these shoals, carry it along shore, and deliver it to beaches. Within the last century, the movement of sand from the Columbia River has been altered by dams, jetties, and other development.


How sand moves along Washington's southwest coast
Source: The Southwest Washington Coastal Erosion Study.
Images courtesy of: Brian Voigt

Southwest Washington Coastal Erosion Study. A recent study of Washington's coastal processes and shoreline changes.

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