The Wash Sediment Cell
The Wash – Sediment cell
‘Coastal process cells are areas within which coarse sediment (sand and gravel) movement is contained.’
- Since the last ice age, The Wash has been a sediment sink. There has been a net accumulation of mud, sand and gravel within it. The vast majority is of marine origin. Some has come from Fenland Rivers.
- Approximately 6.8 million tons of sediment enters The Wash each year from the sea, mostly from the North. Origin of this sediment is most likely the eroding near shore sea bed off central Lincolnshire and the Holderness coast of East Yorkshire. Much of this sediment settles within The Wash.
- Bottom deposits of The Wash range from gravel, through to finer muds and sands.
- Central main channel – characterised by a high proportion of gravel.
- Tide rises and falls twice a day. Average spring tide range is 6.5 metres between high and low water levels at the mouth of The Wash.
- Tidal currents move sediment within the wash.
-History reveals that The Wash is able to adjust to gradual rises in sea-level. However research has shown that erosion has occurred when sea-level rise increases above 5mm/year over a fifty year period.
-Schemes that stopped the supply of sediment from the Holderness coast could have far reaching impacts on the sustainability of The Wash.
-All around The Wash, defence embankments are used to stop the saltmarshes from ‘migrating’. Rising sea levels threaten these marshes. If The Wash saltmarshes were to suffer, they’d lose 363 ha of marsh in 4 years.
-Loss of shingle through leisure of the Norfolk Shoreline.
-The impacts of the Lincolnshire beach renourishment scheme will probably be apparent at Gibraltar Point as longshore drift moves the deposited material south.
‘Coastal process cells are areas within which coarse sediment (sand and gravel) movement is contained.’
- Since the last ice age, The Wash has been a sediment sink. There has been a net accumulation of mud, sand and gravel within it. The vast majority is of marine origin. Some has come from Fenland Rivers.
- Approximately 6.8 million tons of sediment enters The Wash each year from the sea, mostly from the North. Origin of this sediment is most likely the eroding near shore sea bed off central Lincolnshire and the Holderness coast of East Yorkshire. Much of this sediment settles within The Wash.
- Bottom deposits of The Wash range from gravel, through to finer muds and sands.
- Central main channel – characterised by a high proportion of gravel.
- Tide rises and falls twice a day. Average spring tide range is 6.5 metres between high and low water levels at the mouth of The Wash.
- Tidal currents move sediment within the wash.
-History reveals that The Wash is able to adjust to gradual rises in sea-level. However research has shown that erosion has occurred when sea-level rise increases above 5mm/year over a fifty year period.
-Schemes that stopped the supply of sediment from the Holderness coast could have far reaching impacts on the sustainability of The Wash.
-All around The Wash, defence embankments are used to stop the saltmarshes from ‘migrating’. Rising sea levels threaten these marshes. If The Wash saltmarshes were to suffer, they’d lose 363 ha of marsh in 4 years.
-Loss of shingle through leisure of the Norfolk Shoreline.
-The impacts of the Lincolnshire beach renourishment scheme will probably be apparent at Gibraltar Point as longshore drift moves the deposited material south.