Gateway 1 - Coasts Flashcards
What are Coasts?
- Boundary between land and sea covering land that is affected by waves and tides.
- Coast can be cliffed, sandy, rocky, muddy.
Why are Coastal environments different?
1) Variations in human and natural processes
2) Differing coastal environments
3) Diverse landforms formed by coastal processes
Why are Coasts dynamic?
1) Constantly shaped over time due to:
- Coastal processes (E.T.D)
- Coastal Factors (W.T.C.G.E.H)
Factors that affect coastal environments
1) Waves
2) Tides
3) Currents
4) Geology
5) Ecosystems
6) Human Activities
Waves
1) Main shaping force of coastal environments
2) Winds blowing across oceans transferred to surface of water
3) Energy from winds transferred to water shapes coast when breaking on land
Tides
1) Daily alternate rise and fall in sea level
2) Due to gravitational pull of sun and moon
3) Changes every 6hrs, 2 high and 2 low tides/24hrs
4) Affect coastal erosion, transportation and deposition
5) During high tides, waves reach parts of coast not subjected to wave action during low tides.
- More erosion and sediment transportation away from coasts during high tide
Currents
1) Large scale continuous movements of water
2) Driven by prevailing winds blowing in one direction
3) Play important role sediment transportation and temperature regulation
4) Shape coasts through erosion, transportation and deposition
- Cool water away from poles > equator vice versa
- Milder climates in coastal environments
Geology
1) Arrangement and composition of rocks
2) Arranged in layers, alternating layers of hard and soft rocks
- concordant (=), discordant (ll)
3) Rock composition determines hardness and resistance to erosion
4) Different rocks give rise to different coastlines due to different rates of erosion
Ecosystems
1) Plants and animals that interact with each other and environment
2) Coral Reefs
3) Mangroves
Human Activities
1) Living trading fishing and engaging in recreational activities
2) Housing and Transportation
3) Fisheries and aquaculture
4) Recreation and tourism
Factors affecting wave energy
1) Wind speed
- Faster = greater energy
2) Wind duration
- Longer = larger waves = greater energy
3) Fetch
- Greater fetch = greater energy
Waves in open oceans
Long wavelengths, low wave heights
Waves close to shore
1) Approaching coastline
- Base of wave interacts with seabed
- Depth reaches half their wavelength, wave shapes start to change
2) Near coastline
- Base of wave slows due to friction
- Wave height increases, wave length decreases (volume stays the same)
3) Nearest coastline
- Base of wave stops completely due to friction
- Wave crest becomes too steep and topples over
- Releases energy as it breaks on coast
4) Breaking on coastline
- Erodes rocks and transports them away
- Traps air as it crashes, releasing white water
Constructive waves
- Break far from shore
- Deposits finer material, forming gentle slopes
- Strong swash and weaker backwash
- Carries sediment onto shore, minimal sediment eroded
- Builds up coasts overtime, forms beaches
- Frequency: 6-8/min
- Prominent process: Deposition
- Occurs @: Gentle + sheltered coastlines
Destructive waves
- Break violently on shore with high energy
- Finer material transported away
- Leaves coarser materials behind, forms steep coastlines
- Weaker swash (erodes coastline) and strong backwash (Transports sediments away)
- Coasts become more eroded and sediments deplete over time
- Frequency: 10-14/min
- Prominent process: Erosion
- Occurs @: Steep + Open coastlines
