3.1.2.2 Systems and Processes-Brief Description: Waves, Sediment Sources, Waves Weathering, Mass Movement, Transportation.

Coasts as natural systems.

• Coastal environments are naatural, open systems with inputs and outputs and flows between the two. 

Inputs Consist of:

• Energy provided by waves, winds, tides and currents. The enery going into a sytem can sporadically increase in times of a storm or during a storm surge.
• Sediment provided within the sytsem from the erosion of coastlines by waves, as well as that brought by rivers. Weathering and mass movement also contribute material from cliff faces. 
• Change sin sea level- as sea level rises with climat change, thenmore energy is exerted on the costline. 

Outputs Consist of:

• Coastal landforms, both erosional and depositional.
• Accumulations of sediment above the tidal limit (dunes)
• Loss of wave energy through processes such as refraction. 

Stores in the coastal system refer to the water in the sea, and sand/shingle on beaches.

Transfers result from the actions of wind and waves. An example of a transfer mechanism is the process of longshore drift. 

Dynamic Equilibrium

When there is a balance between the inputs and the outputs then the system is said to be in a state of dynamic equilibrium.

If one element in the system changes, (e.g. if because of some outside unfluence, one of the inputs increases without corresponding change in the outputs) then this upsets the equilibrium.

By a process of FEEDBACK, the system may adjust and/or regain its balance/equilibrium. 

There are two types of Feedback:

1. Negative Feedback

2.Positive Feedback.

Negative Feedback

Negative Feedbac occurs when a system acts by lessening the effect of the original change to the second variable then equilibrium is upset.

A negative feedback mechanism acts on the coastal zone to stabalise coastal morphology, (form).

Positive Feedback

Positive feedback occurs within a system where a change causes an effect to snowball, cntinuing it or even accelerating the original change. 

Systems and Processes

Waves:

Waves are caused by the wind blowing over the surface of the sea. As the wind drags over the surface of the water, friction causes  distrurbance and forms waves. Waves at the sea follow an orbital movement and objects on the water do not travel forwards. The resultant up/down movementat sea is called the swell. However, when a wave reaches shallow water, the movement of the base of the wave is slowed by friction with the seabed, the wave spills forwards as a breaker, moving objects forward with it. water rushes up a beach as swash, before drawing back to the sa as backwash. 

wave energy is controlled by...

• force of the wind and its direction 
• duration of the wind
• fetch- the longer the fetch, the more energy the wave possess.

Classification of waves

Constructive waves-  Constructive waves construct or build up the beach and are usually the product of distant weather systems. They have longer wavelengths, lower heights and are less frequent at 6-8 per miute. Swash is greater than backwash, so they add to the beach materials, giving rise to a gently sloping beach. The upper part of such a beach is…