1.1 systems

• The components of open systems

  -inputs- kinetic energy from wind and waves, thermal energy from the sun and potential energy from the position of material on slopes

  -outputs- marine and wind erosion from beaches and rock surfaces

  -processes- stores of beach and nearshore sediment accumulations and flows, such as the movement of sediment along beach by longshore drift
• system feedback in costal landscapes

  -when inputs and outputs are equal a state of equilibrium exists within it

  -could happen when the rate at which sediment is being added to a beach equals the rate the sediment is being removed

  -when equilibrium is disturbed it undergoes self regulation and changes its form in order to restore equilibrium, known as dynamic equilibrium and is an example of negative feedback
• sediment cells

  -its a stretch of coastline and its associated nearshore area within which the Movement of sediment, sand and shingle is largely self contained

  -the boundaries of sediment cells are determined by the topography and shape of the coastline

  -variations in wind direction and tidal currents can cause some sediment to transfer to neighbouring cells
• winds

  -source of energy for costal erosion and sediment transport is wave action

  -wave energy is generated by the frictional drag of winds moving across the ocean surface

  -the higher the wind speed the longer the fetch

  -can carry our erosion, transportation and deposition which shapes many coastlines
• waves

  -a wave possesses potential energy as a result of its position above the wave trough and kinetic caused by the motion of the water within the wave

  -moving waves don’t move water forward but move in a circular motion to the individual water molecules
• Breaking waves

  -friction between the sea floor and water changes the speed direction and shape of the waves

  -firstly waves slow down as they drag across the bottom

  -the wavelength decreases and successive waves start to bunch up

  -the deepest part of the wave slows down more than the top of the wave

  -the wave begins to steepen as the crest advances ahead of the base

  -after a wave has proven, water moves up the beach as awash driven by the transfer of energy that occurs, when the wave breaks

  -when it has no more energy the water is drawn back by backwash
• Tides

  -the periodic rise and fall of the sea surface and are produced by the gravitational pull of the moon and sun

  -highest tides will occur when the moon, sun and earth are all aligned and so the gravitational pull is at its strongest
• tidal range

  -can be a significant factor in the development of costal landscapes

  -in enclosed seas tidal ranges are low and so wave action is restricted to a narrow area of land
• Lithology

  -describes the physical and chemical composition of rocks

  -some rock types have weak lithology, this is because the bonds between the particles that make up the rock are quite weak
• structure

  -the properties of individual rock types such as jointing, bedding, faulting and permeability

  -in porous rocks tiny air spaces separate the mineral particles, these absorb and store water

  -structure is an important influence on the platform of coasts at a regional scale
• rip currents

  -transport costal sediment

  -caused by either tidal motion or by wavs breaking at right angles to the shore

  -a cellular circulation is generated by differing wav heights parallel to the shore

  -water from the top breaking waves with a large height travels further up the shore and returns through the adjacent area where the lower height waves have broken

  -they also cusps, which help perpetuate the rip current, channeling flow through a narrow neck
• terrestrial

  -rivers are major sources of sediment input to the costal sediment budget

  -sediment delivery to the shoreline can be intermittent, mostly occurring during floods

  -the origin of the sediment is the erosion of inland areas by water, wind and ice

  -wave erosion is also the source of large amounts of sediment and makes a major contribution to costal sediment budgets

  -cliff erosion can be increased by rising sea levels and is amplified by storm surge events
• offshore

  -constructive waves bring sediment to the shore from offshore location and deposit it

  -wind also blows sediment from other location, including exposed sand bars, dunes and beaches elsewhere along the coast
• Human

  -beach nourishment is one way in which sediment equilibrium can be mantaines

  -sediment cane be brought in by lorry and dumped on the beach before being spread by bulldozers/pumped onshore by pipeline from offshore sources