Littoral Cell and Sediment Budget

Littoral Cell and Sediment BudgetCoastal GeomorphologyCarlnenus JohnsonOutlineLittoral CellDefinitionExamplesApplicationSediment BudgetDefinitionApplicationExampleLittoral CellDefinitionA coastal compartment that contains a complete cycle of sedimentation including sources, transport paths, and sinksA section of the coast where the budget of sediment is balanced In theory, the transport rate past the up drift and down drift boundaries is zero

Key terms: Sediment Source, Transport Path, Sink

3Littoral CellDefinitionThe sediment sources are commonly:StreamsEroding sea cliffOnshore/offshore sand banksMaterial of biological origin such as shells, coral fragments, and skeletons of small marine organisms.Key terms: Sediment Source, Transport Path, Sink

4Littoral CellDefinitionTransport path(s)along the coast by waves and currents (longshore transport, longshore drift, or littoral drift) Cross-shore (on/offshore) paths may include windblown sand, overwash, and ice-push

Key terms: Sediment Source, Transport Path, Sink

5Littoral CellDefinitionSediment sinks submarine canyons shoals or onshore dune migration, rollover, and deposition in bays and estuaries

Key terms: Sediment Source, Transport Path, Sink

6Littoral CellExamples Types of coastsCollision Sediment Source rivers/cliffs/blufflandsTrailing edge - Sediment Source: headlands/cliffs/shelvedMarginal Sea - Sediment Source: Rivers/deltaArctic Form - Shelf/river/thaw erosionCoral Reef - Reef material

7Littoral CellExamples Types of coastsCollision Sediment Source rivers/cliffs/blufflandsTrailing edge - Sediment Source: headlands/cliffs/shelvedMarginal Sea - Sediment Source: Rivers/deltaArctic Form - Shelf/river/thaw erosionCoral Reef - Reef material

8Littoral CellExamples

9Littoral CellExamples

10Littoral Cell ApplicationIdentify processes that will be disturbed or enhanced by projectsSand mining in river bedDam constructionGroyne construction

11Sediment BudgetSediment BudgetDefinitionApplicationExampleSediment BudgetDefinitionA sediment budget is a tally of sediment gains and losses within a cell over a given time. (US army corps)Sediment budgets are a fundamental tool for managementSediment budget equation

Sediment BudgetDefinition

Sediment BudgetDefinitionGenerally, the methods estimate a likely range of values for the best-known quantities and solve for the lesser-known terms. Volume change data, and removal and placement records usually provide the foundation for the sediment budget. Then, a range of accepted longshore transport rates and a range in relative magnitude of other fluxes are applied to solve the budget. Imbalance of the equation is addressed by varying these parameters, and other terms with great uncertainty, such as offshore losses

Sediment BudgetApplicationTo quantify the flow rate of sediments entering and exiting a defined region of the coast and the surplus or deficit remaining in that region for a particular time period. (long term/short term)To determine the sources and sinks in a littoral cell through application of the primary conservation of mass equation.A tool for regional planning and management

Sediment BudgetExampleNorth New Jersey (1966)

Littoral Cell and Sediment BudgetConclusion :The littoral cell and its budget of sediment are essential planning tools for regional and coastal management.