Coasts Flashcards
Describe the negative feedback loop in a coastal environment?
1) Sediment is eroded during storm
2) Sediment is deposited offshore forming an offshore bar
3) Waves now break before reaching the beach, dissipating their energy and reducing further erosion
4) When the storm calms, normal waves conditions place the sediment in its original position.
Name the inputs of a Coastal system ?
- energy from waves, winds, tides and sea currents
- sediment
-geology of the coastline
-sea level change
Name the outputs of a Coastal system ?
- dissipation of wave energy
- accumulation of sediment above the tidal limit
- sediment removed beyond local sediment cells
What is Backwash ?
The action of water receding back down the beach towards the sea.
Key features of Constructive Waves ?
Waves with a low wave height, long wavelength and low frequency (6-8min). Swash tends to be more powerful than their backwash, therefore sediment builds up
Key features of Destructive Waves ?
Waves with a high wave height, a steep form, a high frequency (10-14min). Their backwash is stronger than their swash, so more sediment is removed.
Describe the process of wave refraction ?
High energy waves strike the headland. The waves are then refracted with a lower energy. Erosion is concentrated at the Headland. Deposition occurs at the bays.
What is Longshore Drift ?
When waves hit the coastline at an angle. This creates a current which runs parallel to the shoreline, resulting in sediment to be transported along the coastline, in the direction of the prevailing wind.
What are Rip Currents ?
These are strong currents moving away from the shoreline. These occur when seawater is piled up along the coastline before flowing into the breaker zone, where the coast direction changes. (dangerous for swimmers)
What is Upwelling ?
The movement of cold water from the deep ocean towards the surface. This creates nutrient-rich cold ocean currents forming part of the global ocean circulation currents.
What are tides ?
The periodic rise and fall of the level of the sea in response to the gravitational pull of the Sun and Moon.
What are spring tides ?
Twice a year when the Moon, Sun and Earth are in a straight line, the tide raising force is strongest. Producing a spring tide.
What is a Sediment Cell ?
A distinct area of coastline separated from other areas by well defined boundaries, such as headlands and stretches of deep water. There are 11 sediment cell in England and Wales.
What is the Coastal Budget ?
Sediment is transferred across the sediment cell, through accretion or erosion.
What are Marine Processes ?
Only operate onto a coastline and are connected with the sea, such as waves, tides and longshore drift.