3.3 - Sediment sources, cells and budgets
SOURCES OF SEDIMENT - the crustal sediments that form depositional features such
as beaches and mudflats originate from the following sources:
Sediment sources:
1. Rivers: sediment will be deposited in river mouths and estuaries where it will be
reworked by waves, tides and currents, accounts for 90% of coastal sediment.
2. Cliff erosion: extremely important in areas of soft or unconsolidated rock (contributes
only 5% or less to coastal systems)
3. Longshore drift: sediment is transported from one stretch of coastline (as an input) to
another stretch of coastline (as an output).
4. Wind: in glacial or hot arid environments, wind-blown sand can be deposited in coastal
regions.
5. Glaciers: ice shelves break into the sea, depositing sediment trapped within the ice
6. Offshore: rising sea levels have meant that sediment from continental shelf areas have
been swept to the shoreline.
7. Biological origin: for example, shells and corals (very small % of sediment budget)
SEDIMENT CELLS
Sediment cell: a stretch of coastline, usually bordered by two prominent headlands, where
the movement of sediment cell is more or less contained.
Figure 3 – The sediment cell system
SOURCES OF SEDIMENT - the crustal sediments that form depositional features such
as beaches and mudflats originate from the following sources:
Sediment sources:
1. Rivers: sediment will be deposited in river mouths and estuaries where it will be
reworked by waves, tides and currents, accounts for 90% of coastal sediment.
2. Cliff erosion: extremely important in areas of soft or unconsolidated rock (contributes
only 5% or less to coastal systems)
3. Longshore drift: sediment is transported from one stretch of coastline (as an input) to
another stretch of coastline (as an output).
4. Wind: in glacial or hot arid environments, wind-blown sand can be deposited in coastal
regions.
5. Glaciers: ice shelves break into the sea, depositing sediment trapped within the ice
6. Offshore: rising sea levels have meant that sediment from continental shelf areas have
been swept to the shoreline.
7. Biological origin: for example, shells and corals (very small % of sediment budget)
SEDIMENT CELLS
Sediment cell: a stretch of coastline, usually bordered by two prominent headlands, where
the movement of sediment cell is more or less contained.
Figure 3 – The sediment cell system
