Waves 5 Flashcards
Are coastlines temporary?
Ya they’re subject to change cuz affected by
- erosion
- sediment transport
- hurricanes and storms
- uplift and subsidence
- sea level changes
Groins
elongated structures perpendicular to shoreline to trap sediments
- fight against longshore drift
label a and b as erosion or deposition:
-> -> -> downcurrent
b || a
[shore]
a = erosion (downdrift)
b = deposition (updrift)
Jetties
preserve inlet or harbour from closing
- built in pairs on each side of opening
- deposition on updrift, erosion on downdrift
Breakwaters
protects shoreline against wave action / erosion
- built a distance away parallel to shore
- dissipate energy as waves hit it
- safe harbour for ships behind it
Tethered float breakwater
dissipates wave energy but allow flow of sediments
- less common
- more expensive
Sea wall
defend coast by reflecting strong waves energy
- sand below wall erodes so wall would collapse eventually
storm surges result from
hurricanes
In the Southern Hemisphere, hurricanes have a ___ rotation. Which side do storm surges hit?
clockwise
storm surges hit on left side
In the Northern Hemisphere, hurricanes have a ___ rotation. Which side do storm surges hit?
counterclockwise
storm surges hit on right side
___ close to the eye wall of the hurricane increases sea surface height by ___
low pressure
pulling up the water
Storm surge
mound of seawater that spills onto land
associated with hurricanes
Storm surges are generated due to
- low pressure in hurricane eye (SMALL surge)
- wind with very high speed (LARGE surge, offset from eye)
are storm surges waves?
not a true wave, just a local change in sea level
of 10m+
how long do storm surges last?
hours to days
