The Coastal System Flashcards
What are the main parts of the system?
Inputs- Energy inputs come through wind, waves, tides, and currents.
Outputs- Sediemnt can be washed out to sea, or deposited further along the coast.
Flows/transfers- Processes such as erosion, weathering, transportation, and deposition can move sediment within the system.
Stores/Components- landforms such as beaches, spits and dunes are stores of sediment.
What is negative/positive feedback?
Negative feedback- when a change in the system causes other changes that have the opposite effect.
Example:
> As a beach is eroded, the cliffs behind it are exposed to wave attacks. Sediment eroded from the cliffs is deposited on the beach, causing it to grow in size again.
Positive feedback- when a change in the system causes other changes that have a similar effect.
Example:
For example, as a beach starts to form it slows down waves, which can cause more sediment to be deposited, increasing the size of the beach.
What are the sources of energy in the coastal system?
Wind:
> During events such as storms, the pressure gradient is very high and winds can be very strong
> Strong winds can generate strong winds, in some areas wind travel in the same direction all the time (prevailing wind) causing higher energy waves.
Waves:
> Waves are created through the wind blowing over the surface of the sea. The friction between wind and surface can cause a circular motion.
> Wave height is affected by the wind speed and the fetch of the wave. The fetch is the maximum distance of sea the wind has blown over.
> As waves approach the shore they break. Friction with the sea bed slows the bottom of the waves and causes them to collapse.
> Water washing up the beach is called the swash. Water washing back towards the sea is called backwash.
Tides:
> Tides are the periodic rise and fall of the ocean surface, caused by the gravitational pull from the sun and moon.
> Tides affect where waves break on the beach, if there is a high tide there is more of a chance of erosion.
Currents:
> A current is the general flow of water in one direction- it can be caused by wind or by variations in water temperature and salinity.
> Currents move material along the coasts.
What are high and low-energy coats?
High energy coast receives high inputs of energy in form of large, powerful waves. High-energy coastlines tend to have sandy coves and rock landforms e.g. cliffs, arches, stacks ad stumps. The rate of erosion is higher than deposition.
Low-energy coasts receive small inputs of energy in the form of small, gentle waves. Some coats are low energy because there is an island offshore, which protects the coast from the full power waves.
Low-energy coats often have saltmarshes and tidal mudflats. The rate of deposition is higher than erosion.
What are the inputs of sediemnt in the coastal system?
> Rivers can carry eroded sediment into the coastal system from inland.
Sea level rise can flood river valleys, forming estuaries.
Sediment is eroded from cliffs by waves, weatheign and landslides.
Sediment can be formed from the crushed shells of marine organisms.
Waves, tides and cuurents.
What are sediment cells?
> The coast is divided into sediment cells.
These are lengths of the coastline that are pretty much entirely self contained for the movement of sediment. This means that processes going on in one cell dont affect the movemnt of sediment in another cell- each cell is a cloased coastal system.
