Coastal Hazards

Most of the sand on continental beaches comes from:

Rivers and floods carrying sediment from the interior of the continent.

Seasonal shifts in weather patterns create different wave action on the beach. In the winter, waves are typically______, and in summer they are typically ______.

destructive / constructive

Winter waves tend to be more energetic, hitting the shore with more force and carrying away more sediment. In the summer, calmer waves often deposit material and are too weak to pull much sand out to sea.

Natural systems like large sand beaches and mangroves along the coast act as important hazard mitigation tools primarily because:

They absorb wave energy that would otherwise erode the coast.

Longshore drift is the result of waves coming in at an angle to the beach. It causes sand to move:

Along or parallel to the shoreline

On a ________ shoreline, natural processes add more material (sand, rocks, etc.) than what is taken away by erosion.

depositional

An erosional coastline is likely to have which of the following hazards?

crumbling or unstable cliffs.

Seawalls are concrete structures designed to protect the shoreline from storm damage. Seawalls:

Are a short-term solution to coastal erosion

While seawalls create a temporary barrier that may help for a short time, they actually increase the energy focused on the shore in front of the wall, speeding up erosion.

Ocean tides on Earth are more strongly influenced by the gravitational pull of:

the Moon

While the Sun is much larger and has a much stronger gravitational effect, it is much farther away. The moon, although much smaller, is very close and is the primary driver of tides on Earth.

Tidal Bores, which can be dangerous waves, occur where:

The geography of the shore funnels rising tide water in to a narrow bay or river channel

Which of the following engineered structures is the most effective at stopping the down-current (or longshore) migration of sand?

Jetty

most effective at stopping sand from moving with the longshore current. That's why they are used to protect shipping lanes from sand accumulation.