Sediment dynamics on a steep, megatidal, mixed sand–gravel–cobble beach
Results are presented from a pilot study of shore-face sediment dynamics on a steep, poorly sorted, coarse-grained, megatidal beach at the head of the Bay of Fundy, Nova Scotia, Canada. The experiment involved the first field deployment of a prototype wideband, pulse-coherent, bistatic acoustic Dopp...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2014-08-01
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| Series: | Earth Surface Dynamics |
| Online Access: | http://www.earth-surf-dynam.net/2/443/2014/esurf-2-443-2014.pdf |
| Summary: | Results are presented from a pilot study of shore-face sediment dynamics on a
steep, poorly sorted, coarse-grained, megatidal beach at the head of the Bay
of Fundy, Nova Scotia, Canada. The experiment involved the first field
deployment of a prototype wideband, pulse-coherent, bistatic acoustic Doppler
profiling system. Measurements of the vertical structure of flow and
turbulence above a sloping bed, as well as bed material velocity, demonstrate
the capabilities of this instrument vis-à-vis studies of nearshore sediment
dynamics at the field scale. The second focus of the paper is the unexpected
observation that the surficial sediment median diameter, across the lower
two-thirds of the intertidal zone, underwent a pronounced <i>decrease</i> when
wave forcing was <i>more</i> energetic, compared to values observed during
calmer conditions. The explanation for this result appears to involve the
formation – in wave-dominated conditions – of metre-scale wavelength, 20 cm high
ripples on the rising tide, which are then planed flat by the swash and/or
the shore break on the subsequent ebb. |
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| ISSN: | 2196-6311 2196-632X |