Offset Coastal Inlets. Forms of Sediment Accumulation in the Beach Zone.
MASSACHUSETTS UNIV AMHERST COASTAL RESEARCH CENTER
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Offset coastal inlets are common on the coasts of New England and the northern Gulf of Alaska. In both areas, the dominant waves approach the shore at an oblique angle, resulting in a strong net littoral drift. The most common type of offset on these coasts is a downdrift offset i.e., the downdrift side of the inlet protrudes further seaward than the updrift side. Wave refraction around the ebb-tidal deltas at the inlets is an important process in the formation of the downdrift offsets, inasmuch as it creates a local reversal in drift direction just downdrift of the inlet, and allows sediment to accumulate there. Forms of sediment accumulation in the beach zone include ridge-and-runnel systems, berms, a multiplicity of types of nearshore bars, cusp-type sand waves or rhythmic topography, complex sand bodies affiliated with ebb-tidal deltas, and an ordered system of minor features bedforms that correlate with flow-regime conditions. Most sand beaches undergo a simple cycle of erosion and deposition in response to the passage of coastal storms. Author
- Physical and Dynamic Oceanography
- Civil Engineering