sediment cells x

• what are sediment cells?

  self-contained, closed systems (as most sediment movement is contained within the cell
• How many sediment cells are there around the English and Welsh coastline?

  11

  they are divided into sub-cells where the inputs, transfers, stores and outputs within the system can be identified
• What are sources of sediment?

  cliff erosion

  eroding beaches

  eroding spits

  eroding wave cut platforms

  fluvial sediment

  eroding spits
• What are sources?


  locations where sediment is generated
• What are transfers?


  locations where sediment is moving alongshore through longshore drift and offshore currents
• What are sinks?


  locations where the dominant process is deposition and depositional landforms are created such as spits and offshore bars
• What is the sediment budget?

  the amount of sediment available to the sediment cell
• What are permanent stores?


  estuary

  dredging

  offshore bars
• What are temporary stores?

  beaches

  dunes

  spits
• Why are beaches, dunes and spits temporary stores/sinks?

  as over time the sub-sinks will erode and the sediment will re-enter the cell's system
• the sediment cell will produce depositional features which are in equilibrium with the amount of sediment available (sediment budget)
• what occurs if the sediment budget is decreased?


  the waves will continue to move sediment causing erosion in some areas???
• what occurs if the sediment budget is increased?

  more deposition is likely
• what effect do groynes have on sediment cells?

  groynes block the movement of sediment, which can lead to beach erosion further downdrift

  there is less sediment to protect against erosion
• why are groynes used?

  to trap sediment in areas where a beach is considered essential either for leisure or the protection of cliffs

  this causes terminal groyne syndrome: causes sediment build up on one side of the groyne, but starves an area of sediment on the other side making it more vulnerable to erosional processes
• what is the effect of dams on sediment cells?

  reduce the volume of fluvial sediment entering the coastal system
• • the coastal system is a complex and dynamic system which will adapt according to wave energy levels and sediment supply
  • a change in one part of the system causes the whole system to work to compensate for the change to achieve equilibrium
• • sediment is constantly generated in the source region and deposited in the sink region
  • dynamic equilibrium is reached when inputs of sediment from the source region are balanced by the amount being deposited in the sinks