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Coastal & Marine Geology Program > National Assessment of Coastal Change Hazards > Open File Report 03-337

An Overview of Coastal Land Loss: With Emphasis on the Southeastern United States

USGS Open File Report 03-337

by: Robert A. Morton

Summary
Introduction
Physical Agents of Land Loss:
Waves, Currents, & Storm Surges
Landslides & Cliff Retreat
Sediment Budget
Relative Sea Level
Climate & Land Loss
Role of Shoreline Characteristics:
Composition, Induration, & Saturation
Coastal Morphology & Vegetation
Role of Human Activities:
Introduction
Transportation
Coastal Construction
River Modification
Hydrocarbon & Groundwater Extraction
Climate Alteration
Coastal Excavation
Wetland Losses
Acknowledgments
References

Physical Agents of Land Loss: Sediment Budget

Introduction

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.

Coastal & Marine Geology Program > National Assessment of Coastal Change Hazards > Open File Report 03-337


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