X. The Coast: Beaches and Shoreline Processes (Chapter

10)

byAl Trujillo

Hard Stabilization: Jetties, Groins, and Breakwaters

Jetties: Always in pairs; built to protect a harbor entrance

Groins: Individual or many (if many = “groin field”); built to trap sand

Ex: Groin

• A groin has nothing to do with human anatomy…

• Why is a groin built?

• So that the beach is wide in front of your house!

Your house

Neighbor’s house

New groin

Ex: Breakwater

• A hard, rocky structure built parallel to shore and attached to the sea floor

• A few feet above sea level

• Designed to break waves and make quiet water behind

Curved breakwater, Greece

Case Study: Coastal Stabilization

Structures• Work together with your Success Team• Need: Case Study Handout (1 per team)• Rules:

Closed book (starting now!)Can use your notesRank each character’s ideaPut your rankings (#1, #2, #7) on the

boardBe prepared to discuss your choices

Case Study: Santa Monica, California

See Figure in Trujillo and Thurman textbook

After breakwater (1949)Before breakwater (1931)

Dredge

Breakwater destroyed by

waves in 1983

Case Study: Santa Monica, California

• Video: The Beach: A River of Sand (Part II)Shows Santa Barbara Harbor and the

problem its shore-connected breakwater created

Look for the Santa Monica breakwater (our Cast Study)

Good underwater footage of La Jolla Submarine Canyon

X. The Coast: Beaches and Shoreline Processes (Chapter

10)

byAl Trujillo

End