coastal zones Flashcards
What influences wave height?
Wind velocity, wind duration, wind fetch
Wind is influenced by temperature & pressure
What are the different types of currents?
Rip, longshore, littoral
How do rip currents form?
Series of large waves arrive at coastline & break on the beach, piling up and concentrating in narrow zones
How do longshore currents form?
A current of water and moving sediment that develops in the surf zone as the result of waves that strike the land at an angle
How do littoral currents form?
- Segment of coastline that includes an entire cycle of sediment delivery to the coast, longshore littoral transport, and eventual loss of sediment from the nearshore environment.
- Swash-pushing sediment onshore at an oblique angle
How does erosion shape coastlines?
Wave action plays a large role in how coastlines look and are formed, which is exacerbated by changes in sand supply, severe storms, rises in sea levels, and human interference with natural shore processes
How do we manage coastal erosion, and restore coastlines, and what are the strengths and weaknesses of our approaches?
Hard stabilization = structures built to protect shoreline from waves
- Often interfere with littoral transport and create unwanted deposition & erosion
Soft stabilization = adding sand to beaches
- It’s very costly
What are some examples of hard stabilization?
- Seawalls = structures made of concrete, boulders, wood parallel to shore with objective of stopping coastal erosion
- Jetties = pairs at the mouth of a river (etc.) to stabilize channel & minimize deposition into channel
- Groins = depleting updrift beach of sand, build groin to trap sand in one side (perpendicular)
- Breakwaters = intercepts waves to provide a protected areas for boats
(attached or separated)
What is an example of soft stabilization?
Beach nourishment = removing sand from the ocean to place on the beach
Why are coastal areas at risk for natural hazards?
Creation of tropical cyclones (typhoon/hurricanes) in the ocean will make landfall in coastal areas, and that is where it will be the most damaging (loses energy once it makes landfall)
What causes tides?
The gravitational force acts on the ocean and works with centrifugal force
What is fetch?
Distance wind blows across the surface
What is the wave base?
Maximum depth at which water wave’s passage causes significant water motion
What causes waves to break as they approach shore?
When wave height is 2/3 of wave base
If you are caught in a rip current, what should you do to survive?
Swim parallel to the shore until you’re out of the rip zone
