Erosion is carving into Southwest Washington beaches. Erosion rates at Cape Shoalwater have averaged over 100 feet per year for a century.
In recent decades, new erosion hot spots have developed. Storm waves near the Grays Harbor South Jetty threatened City of Westport facilities and a state park. Another erosion hot spot is at Ocean Shores, north of the Grays Harbor North Jetty. This beach had been growing since the jetty was built in the 1900's, but has recently begun to erode, threatening development. Erosion is also cutting into
Cape Disappointment State Park (formerly Fort Canby); up to 90 camp sites could be lost to erosion by the year 2009, scientists with the Southwest Washington Coastal Erosion Study predict.
What's happening on Washington's southwest coast?
To understand the erosion problems on southwest Washington's coast, the Washington State Department of Ecology and the U.S. Geological Survey began a study in 1996. The Southwest Washington Coastal Erosion Study has been investigating coastal change and processes. Findings from the study will help coastal communities plan and prepare for coastal hazards.
How the coast works
Erosion along Washington's southwest coast is affected by: jetties, dams, sediment supply, geologic history, wave action, and weather.
The Southwest Washington Coastal Erosion Study.
- Jetties caused beaches to grow and possibly erode
Jetties have influenced accretion and possibly erosion patterns on the beaches over distances of 12 miles (20 kilometers) or more.
- Dams on the Columbia River have reduced the sand supply
Dams on the Columbia River have reduced the sand supply to coastal beaches by two thirds.
- Beach growth has slowed
Accretion rates along the coast have slowed dramatically over the past few decades.
- Beaches that once grew rapidly are now eroding
High rates of erosion are occurring along sections of beach that previously grew most rapidly.
- El Niño impacts the shoreline
El Niño, a recurring atmospheric phenomenon, can bring higher sea levels, intense storms, and extreme high waves from the southwest.
- Earthquakes hit Washington's coast
Large earthquakes in the past caused the coast to sink 3 to 6 feet suddenly (1 to 2 meters).
- Columbia River sand built beaches and barriers
Supplied by sand from the Columbia River, beaches on the Long Beach Peninsula grew for 4,000 to 5,000 years.
Images courtesy of: Brian Voigt