Physical Agents of Land Loss: Sediment Budget
Sediment budget is a concept that applies to sandy and muddy shores. It is only one of three factors (sediment budget, sea level and wave energy) that control most land loss. Sediment budget refers to the balance between sediment added to and removed from the coastal system; in this respect the coastal sediment budget is like a bank account. When more material is added than is removed, there is a surplus of sediment and the shore builds seaward. On the other hand, when more material is removed than is added, there is a deficit in sediment supply and the shore retreats landward. Coastal erosion is a physical expression of a deficit in the sediment budget where nearshore processes remove more material from the shore than is added. Stated another way, coastal recession is the result of insufficient sediment supply compared to sediment removal.
Sediment budget also refers to the sources that deliver sediment to the coast and the places where it is temporarily or permanently stored. The storage sites are known as sediment sinks. To calculate the sediment budget for a coastal segment, one must identify all the sediment sources and sinks, and estimate how much sediment is being added to or taken from the beach each year. This is an extremely difficult task and as a result, few sediment budgets have been accurately determined.
U.S. Department of the Interior, U.S. Geological Survey
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Last modified: 23:12:55 Sat 12 Jan 2013
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