Pacific coast

• steep beaches
• narrow surf zone
• strong wave attack
• Submarine canyons funnel sediment to deep ocean.

• Less steep, wave attack spread out.
• Protected by barrier islands.
• Most sediment from local erosion and offshore.

• dams reduce coastal sediment supply
• Sea level rise:
•     greater shoreline shift on Atlantic coast
•     as sea level rises, barrier islands retreat landward through washover
• To stop longshore drift, groins are built.
•     BUT, erosion is increased downcurrent.
• Sand deposits behind breakwaters, built to protect shore from waves
• Disturbance of dunes leads to:
• erosion
•  less protection for inland areas

Solutions?

• Sea walls protect coast.
• BUT, reflected wave energy erodes beach, nearby coast.
• Pumping sand around harbor jetties
• “Nourish” beaches (bring in sand)
• BUT, adding sand is temporary.
• Plan for coastal erosion. Migrate with coastline

Other human effects:
Pollution

Reefs: composed of framework of skeletons of living organisms (often corals)
require shallow, warm, clear water
are currently dying

Cause (?):
algae growth due to nutrients from septic tanks
bleaching due to warmer temperatures