Sediment Transport Processes at Sandbridge, VA

by Suzette M. Kimball, Virginia Inst of Marine Science, United States,
L. D. Wright, Virginia Inst of Marine Science, United States,

Document Type: Proceeding Paper

Part of: Barrier Islands: Process and Management


Sandbridge Beach is a primarily residential community located along a 7 km reach of narrow barrier beach. Rates of erosion in this area historically have been high, reaching as much as 3 m/year for the period 1925 to 1980. Recent evaluations by the Virginia Institute of Marine Science (VIMS) of the subaerial portion of the shoreface indicate an average volume loss of 148,000 m3/year over the reach. Storms during 1987 and 1988 resulted in exposed septic fields and structural damage to oceanfront homes and community roads. With continued risks posed by increasing sea level and decreasing sand supply, and as development pressures increase, the erosion and storm hazards have become critical. This study documents the natural processes affecting Sandbridge Beach and evaluates the effectiveness of various mitigative measures. A numerical hydrodynamic model has been developed to evaluate wave modifications by shoaling, refraction, diffraction, bottom-induced frictional dissipation and wave-current interaction. Analyses indicate that the steep shoreface profile fronting Sandbridge Beach results in breaking storm waves that are much larger than at beaches to the north and south which are fronted by broad shallow shoals. The longshore variations in breaker height contribute to gradients in net longshore sand transport. Additional aspects of the subject are discussed.

Subject Headings: Sediment transport | Wave shoaling | Soil pressure | Sandy soils | Numerical models | Wave refraction | Coastal processes | Sea water | Virginia | United States

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