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Observations of mixing and transport on a steep beach

Observations of mixing and transport on a steep beach

Authors :
Alan L. Shanks
Edie L. Gallagher
Ad Reniers
Edward B. Thornton
Jenna Brown
Jamie MacMahan
Steven G. Morgan
Naval Postgraduate School (U.S.)
Oceanography
Source :
Brown, Jenna A; MacMahan, Jamie H; Reniers, Ad JHM; Thornton, Ed B; Shanks, Alan L; Morgan, Steven G; et al.(2019). Observations of mixing and transport on a steep beach. Continental Shelf Research, 178, 1-14. doi: 10.1016/j.csr.2019.03.009. UC Davis: Retrieved from: http://www.escholarship.org/uc/item/7hr270dm, Continental Shelf Research, 178
Publication Year :
2019
Publisher :
eScholarship, University of California, 2019.

Abstract

The article of record as published may be found at http://dx.doi.org/10.1016/j.csr.2019.03.009 Surfzone mixing and transport on a sandy, steep (∼1/8 slope), reflective beach at Carmel River State Beach, California, are described for a range of wave and alongshore flow conditions. Depth-limited wave breaking occurred close to the shore due to the steepness of the beach, creating a narrow surf/swash zone (∼10 m wide). Fluorescent Rhodamine dye was released as a slug in the surfzone, and the temporal and spatial evolution was measured using in-situ dye sensors. Dye concentration measured as a function of time reveals sharp fronts that quickly decay resulting in narrow peaks near the dye release, which subsequently broaden and decrease in peak concentration with alongshore distance. The measurements indicate two stages of mixing and transport occur inside the surfzone on the steep beach. 1) In the near-field (50 m downstream from the dye release location), the mass transport was dominated by advection. The distance to the far-field is much shorter in the alongshore on a steep beach compared with a dissipative beach. Estimates of cross-shore and alongshore diffusion coefficients (κₓ, κᵧ) were found to be similar in magnitude within the surfzone. Outside the surfzone in the far-field, the results suggest that the mixing processes are independent of those inside the surfzone. The mixing and transport of material observed on this steep beach are found to be analogous to that previously measured on dissipative beaches, however the diffusion coefficients within and outside the surfzone were found to be smaller on this steep beach. National Science Foundation (OCE0926750) Department of Defense through the National Defense Science and Engineering Graduate (NDSEG) Fellowship Naval Research (ONR DURIP #N0001409WR20268)

Details

Language :
English
ISSN :
02784343
Database :
OpenAIRE
Journal :
Brown, Jenna A; MacMahan, Jamie H; Reniers, Ad JHM; Thornton, Ed B; Shanks, Alan L; Morgan, Steven G; et al.(2019). Observations of mixing and transport on a steep beach. Continental Shelf Research, 178, 1-14. doi: 10.1016/j.csr.2019.03.009. UC Davis: Retrieved from: http://www.escholarship.org/uc/item/7hr270dm, Continental Shelf Research, 178
Accession number :
edsair.doi.dedup.....c51ed2cd47c7fabba6a699a474df4784
Full Text :
https://doi.org/10.1016/j.csr.2019.03.009.