Ocean Chapter 10

Seawall

one of the most destructive type -built parallel to shore -armors coastline and protects landward developments from ocean waves

In the long term, what do beach drift and longshore current do?

Move sediment parallel to shoreline

In which direction does the longshore current move?

Parallel to shore

What would you do to both grow a large beach and protect a harbor mouth?

Place two jetties on either side of the harbor mouth, and build a breakwater upcurrent from the harbor mouth.

Which of the following structures are types of coastal stabilization structures?

jetties groins breakwaters

How are winter beaches different from summer beaches?

Winter waves are short and high, whereas summer waves are long and shallower.

Why are coastal stabilization structures built along coastlines?

-to protect coastal property from wave erosion -to stop beach sand erosion

How long does it take berms to become narrow and rocky after summer has passed?

A few weeks

Which way would sediment move if NO beach drift existed?

At an angle to shore

In general, what do beaches look like at the end of winter?

Beaches tend to have a narrow berm and a prominent longshore bar.

How would a beach be affected if a wide berm were protected from erosion during winter months?

The wintertime beach would look similar to the summertime beach.

What is the longshore current?

Water forced by waves to move along the shore

Breakwater

built parallel to a shoreline -harbor

Groin

built perpendicular to a coastline and are specifically designed to trap sand moving along the ocast in longshore transport -large blocks of rocky material (rip-rap)

Jetty

built perpendicular to the shore and is usually constructed of rip-rap -usually built in closely spaced pairs and can be quite long, they can cause more pronounced upcoast depositon and downcoast erosion -protect harbor entrances from waves and only secondarily does it trap sand

How do jetties protect harbor entrances?

by inhibiting the deposition of sand in the harbor mouth

Hard Stabilization

structures built to protect a coast from erosion or to prevent the movement of sand along a beach

In general, what do beaches look like at the end of summer?

Beaches tend to have a wide berm and no longshore bar