Sediment Cells

• Sediment Cell - Sections of the coast bordered by prominent headlands. Within these sections, the movement of sediment is almost contained and the flows of sediment should act in dynamic equilibrium.
• Sediment cells are areas along the coastline and in the nearshore area where the movement of material is largely self-contained. They can be considered as a closed coastal sub-system as far as sediment is concerned.
• A sediment cell is a largely self-contained stretch of coastline. They are regarded as closed systems as sediment is not usually transferred from one to the other.

  
• The boundaries of the sediment cells tend to be headlands and peninsulas which act as natural barriers to stop the further movement of the sediment.
• A sediment budget is the balance between changes in the volume of sediment held within the system and the volume of sediment entering or leaving the system.
• A positive budget is when there are more inputs than outputs to the system and a negative budget is when outputs are higher than inputs. The budget can alter according to the following factors:

  • Input changes
  • Output changes
• Input changes: volume of fluvial material being deposited into the coastal system and the impact that human intervention can have on that, e.g. damming a river. Coastal defences can impact upon the inputs too with reduced cliff face erosion taking place. Sea level rise may add more sediment with increased coastal erosion
• Output changes: human intervention, such as removing large amounts of sand from an area for industrial or coastal protection use. Also, sea level rise can increase the likelihood of changing ocean currents and material being removed from sediment cells.
• The only inputs into the sediment come from erosion from the sea bed or land
• Human activity such as beach management can interrupt the natural system creating imbalance within the cell leaving some areas at risk of erosion