SEDIMENT SOURCES (inputs)
- Rivers + streams reaching the coast (river erosion)
- Subaerial system (runoff, weathering, mass movement (eg mudslide))
- Longshore drift from other sections of the coast
- Marine system (offshore sandbanks)
- Material from a biological origin (incl shells, coral fragments + skeletons of marine
organisms)
- Estuaries
- Cliff erosion
- Man generated debris
Sediment (littoral) cells
- Sediment – sand, silt, shingle, marine, debris
- Sediment movements occur in distinct areas or sediment cells, within which inputs + outputs
are balanced, flows of sediment are in dynamic equilibrium
- In theory sediment cells are closed systems but it’s easy for fine sediment to enter
neighbouring cells
Sediment cell = a length of coastline within which the movement of sediment is largely self-
contained (erosion and deposition balanced)
Coastline of England + Walles
- 11 sediment cells
- Broken into sub-cells (allowing closer study + management)
- Separated by well-defined boundaries (headlands/deep waters)
- Longshore drift redistributes sediment (takes from area of erosion (source) to area of
deposition (sink))
How can people affect the equilibrium of a sediment cell?
Disrupting inputs:
- Coastal defence (groynes, jetties, harbour walls, sea walls) as they block movement of
sediment
- River dams (cut down amount of fluvial sediment entering coastal system)
- Protecting soft cliffs can prevent cliff falls reducing amount of sediment entering system
Beach nourishment
- Increase amount of sediment on a beach, preserving and protecting the coastal environment
- Rivers + streams reaching the coast (river erosion)
- Subaerial system (runoff, weathering, mass movement (eg mudslide))
- Longshore drift from other sections of the coast
- Marine system (offshore sandbanks)
- Material from a biological origin (incl shells, coral fragments + skeletons of marine
organisms)
- Estuaries
- Cliff erosion
- Man generated debris
Sediment (littoral) cells
- Sediment – sand, silt, shingle, marine, debris
- Sediment movements occur in distinct areas or sediment cells, within which inputs + outputs
are balanced, flows of sediment are in dynamic equilibrium
- In theory sediment cells are closed systems but it’s easy for fine sediment to enter
neighbouring cells
Sediment cell = a length of coastline within which the movement of sediment is largely self-
contained (erosion and deposition balanced)
Coastline of England + Walles
- 11 sediment cells
- Broken into sub-cells (allowing closer study + management)
- Separated by well-defined boundaries (headlands/deep waters)
- Longshore drift redistributes sediment (takes from area of erosion (source) to area of
deposition (sink))
How can people affect the equilibrium of a sediment cell?
Disrupting inputs:
- Coastal defence (groynes, jetties, harbour walls, sea walls) as they block movement of
sediment
- River dams (cut down amount of fluvial sediment entering coastal system)
- Protecting soft cliffs can prevent cliff falls reducing amount of sediment entering system
Beach nourishment
- Increase amount of sediment on a beach, preserving and protecting the coastal environment
