Sediment sources, cells and budgets

What are the 6 sediment sources?

• offshore

• Glaciers

• Cliff erosion

• Rivers

• Longshore drift

• Wind

Offshore sediment source

• sediment from offshore can be transferred into the coastal ( littoral ) zone by waves, tides and currents

Glacier sediment source

• ice shelves calve ( chunks of ice breaking off a glacier or ice sheet) into the sea depositing sediment trapped within the ice

Cliff erosion sediment source

• the extensive till cliffs along the Holderness coast comprise of sand and clay has 10m of erosion where as hard rock in Cornwall takes a lot longer to erode - different amounts depending on rock type

River sediment source

• sediment is transported down rivers in the river mouth then it is reworked with waves, tides and currents

Long shore drift sediment source

• sediment is transported from one stretch of coastline (output) to another stretch of coastline (input)

Wind sediment source

• in glacial/hot arid environments wind blown sands can be deposited in coastal regions, sand dunes represent both accumulation of sand and potential sources

What is a sediment cell?

• a stretch of coastline that moves sediment within the cell around

• the sediment is mostly contained in the cell

• The inputs of the cell usually come from a river where sediment has been transported from upstream and deposited

• It is then transferred through processes such as longshore drift and currents which are deposited on the beach or sand dunes

• Human activity such as beach management can interrupt the natural system creating an imbalance

What type of system is a sediment cell?

A closed system

What are the sediment cells in the uk?

• 1- st Abbas head

• 2-flambrough head

• 3- the wash

• 4- the river Thames

• 5- selsey bay

• 6- Portland bill

• 7- lands end

• 8- st David’s head

• 9- bardsey sound

• 10- great orme

• 11- solway firth

What is the coastal sediment budget?

• 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.