Unit 2 - Dynamic Shorelines Flashcards
What are the six types of coastlines?
Permafrost coasts, Sandy beaches, Rocky beaches, Wetlands and marshes, Cliff-backed beaches, Estuaries
What is the most dynamic part of the beach?
surf zone
Where is the surf zone located?
extends from the breaker zone to the shore
When do waves break in the surf zone?
when water depth is ~1.5x wave height
How do waves in the surf zone break?
Can break as a spilling breaker on low gradient slopes, a plunging wave on moderate gradients, or a surging wave on steep slopes
What occurs during breaking?
waves transform potential energy to kinetic energy, manifesting as wave bore moving shoreward as broken white water
What can happen at the shoreline?
currents can be deflected alongshore and water may return seaward as a rip current
What does a rip current facilitate in terms of water movement?
drives transport between inner shelf and surf zone.
What causes a rip current?
Incoming waves push water toward shoreline, creating imbalance of water piling up in surf zone.
Where is a rip current typically the strongest?
break in sandbar where water seeks path of least resistance back through surf.
What happens to a rip current’s strength after passing through a narrow gap?
It begins to spread out, considerably weakening the velocity and strength of the rip current circulation.
What fish species do surf zones support?
- large elasmobranchs that are of international conservation concern, such as white sharks
- heavily harvested bony fishes, such as tailor.
What are fish assemblages in surf zones impacted by?
- intense recreational fishing
- commercial netting
- coastal urbanization
- beach modification
What effects does the environment have on surf zone ecosystems?
direct, but often hard to understand
What happens when broken waves reach the base of the wet beach?
they collapse and run up the beach face as swash in the swash zone