Coastal landscapes can be viewed as systems

Inputs = Kinetic energy from wind/waves. Sediment from weathering, mass movement and
fluvial discharge.
Outputs = Aeolian and marine erosion, dredging and mining and offshore sediment transfer.
Throughputs = Stores of beach sediment and flows such as longshore drift.
System is in equilibrium when inputs/outputs are balanced, however coasts are in dynamic
equilibrium as the balance is often disturbed. Feedback restores equilibrium and can be
positive (brings about change in the same direction) or negative (restores to normality).
Sediment Cells = A stretch of coastline within which the movement of sediment, sand and
shingle is largely self-contained. There are 11 cells (split into sub-cells) around England and
Wales determined by coastline shape, topography and large physical features which act as
natural barriers.