Mixing in the Surf Zone

Harris, T.F.W.; Jordaan, Jan M.; McMurray, William; Verwey, C.J.; Anderson, F P

doi:10.1016/b978-1-4832-8391-3.50047-6

Cited by 23 publications

(34 citation statements)

References 2 publications

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“…A literature review has indicated that the only known experimental studies which incorporate the overall on-off shore mixing within the surfzone were studies undertaken by Harris et al(1963), Inman et al(1971, Tanaka et al(1980), Pearson et al (2009), andClarke et al (2010). Figure (9) shows the relationship between measured on-off shore dispersion (D y ) using tracer studies, and the predicted onoff shore dispersion identified within this study.…”

Section: Resultsmentioning

confidence: 99%

“…Some site specific field studies have been undertaken, however, the contribution to mixing due to wave activity is difficult to interpret as all the associated parameters responsible for the transport processes were not measured. Tracer Studies: Inman et al (1971) referred to the studies of Harris et al (1963) who undertook a series of experiments in both the field and laboratory to investigate the mixing of a solute when released into the surf zone. Both field and laboratory-based experiments produced results which suggested that the mixing across the surf zone is proportional to H 2 /T, where H is the crest to trough wave height and T is the wave period.…”

Section: Previous Workmentioning

confidence: 99%

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Solute Dispersion in the Nearshore Due to Oblique Waves

Abolfathi

Pearson

2014

Int. Conf. Coastal. Eng.

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An experimental study has been conducted in a large scale basin at Danish Hydraulic Institute (DHI). Simultaneous measurements of hydrodynamics using Laser Doppler Anemometry (LDA) and fluorescent tracer studies were undertaken within the surfzone under a regular wave condition with waves approaching the shore at 20. Through a series of hydrodynamic and tracer measurements and their comparison with the existing theoretical values, this study quantifies the physical processes and their integrated effects on a solute tracer in the nearshore zone subject to combined waves and the induced longshore currents. A theoretical dispersion model has been developed, adopting both experimental and theoretical velocimetry approaches. The results of theoretical model have been compared to the tracer data. Using the results from this study together with all known previous studies of dispersion measurements within the surfzone, good agreement exists.

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Section: Resultsmentioning

confidence: 99%

Section: Previous Workmentioning

confidence: 99%

Solute Dispersion in the Nearshore Due to Oblique Waves

Abolfathi

Pearson

2014

Int. Conf. Coastal. Eng.

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“…The coast has a subtropical climate with a mean annual rainfall of 1009 mm. The mean surf zone temperature is 21.6°C, but ranges from 12.8-28.3°C (Harris et al, 1962). The area of the South Coast that was searched for spraints (otter faeces) included sites from Hibberdene in the north to the Zolwane River in the south (south of Port Edward) (Fig.…”

Section: Kzn Coastmentioning

confidence: 99%

An Assessment of Spatial and Temporal Variation in the Diet of Cape Clawless Otters (Aonyx capensis) in Marine Environments

Jordaan

McIntyre

Somers

et al. 2015

African Journal of Wildlife Research

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We studied the diet of Cape clawless otters (Aonyx capensis) at three sites along the eastern and southern coast of South Africa to assess possible spatial variation along a community species richness and biomass gradient associated with rocky shores. A total of 309 spraints representing two seasons (summer 2013/2014 and winter 2014) were collected and subsequently analysed. The percentage occurrence and percentage dry mass of numerous prey categories were compared between sites and seasons. Variation in the importance of prey items was found between sites, whilst no variation was found between seasons within the same site. Crab was the most important prey item in the southernmost study area (Tsitsikamma National Park) and at the northernmost study site (KwaZulu-Natal Coast), whilst lobster was the most important prey item in the central area (Mkambati Nature Reserve). Fish was the second most important prey item at all three sites. Our results suggest that otters are opportunistic feeders that are likely able to adapt to potential prey species and abundance changes associated with current and future anthropogenically driven changes. Furthermore, long-term, site-specific stability in diet suggests that monitoring the diet of otters could provide some useful information on the status of shoreline communities.

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“…Several field experiments have tracked Lagrangian surface drifters on alongshore-uniform beaches [e.g., Spydell et al, 2007Spydell et al, , 2014 and rip-channeled beaches [e.g., Brown et al, 2009;MacMahan et al, 2010;Brown et al, 2015] to investigate dispersion in the nearshore. Similarly, fluorescent dye [e.g., Harris et al, 1963;Inman et al, 1971;Grant et al, 2005;Clark et al, 2010] has also been used to explore nearshore mixing. However, many of these observations were limited by sparse sampling or small spatiotemporal domains.…”

Section: Introductionmentioning

confidence: 99%

Surfzone to inner‐shelf exchange estimated from dye tracer balances

et al. 2015

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Surfzone and inner‐shelf tracer dispersion are observed at an approximately alongshore‐uniform beach. Fluorescent Rhodamine WT dye, released near the shoreline continuously for 6.5 h, is advected alongshore by breaking‐wave‐ and wind‐driven currents, and ejected offshore from the surfzone to the inner‐shelf by transient rip currents. Novel aerial‐based multispectral dye concentration images and in situ measurements of dye, waves, and currents provide tracer transport and dilution observations spanning about 350 m cross‐shore and 3 km alongshore. Downstream dilution of near‐shoreline dye follows power law decay with exponent −0.33, implying that a tenfold increase in alongshore distance reduces the concentration about 50%. Coupled surfzone and inner‐shelf dye mass balances close, and in 5 h, roughly half of the surfzone‐released dye is transported offshore to the inner‐shelf. Observed cross‐shore transports are parameterized well ( , best fit slope ) using a bulk exchange velocity and mean surfzone to inner‐shelf dye concentration difference. The best fit cross‐shore exchange velocity is similar to a temperature‐derived exchange velocity on another day with similar wave conditions. The magnitude and observed inner‐shelf dye length scales, time scales, and vertical structure indicate the dominance of transient rip currents in surfzone to inner‐shelf cross‐shore exchange during moderate waves at this alongshore‐uniform beach.

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Mixing in the Surf Zone

Cited by 23 publications

References 2 publications

Solute Dispersion in the Nearshore Due to Oblique Waves

Solute Dispersion in the Nearshore Due to Oblique Waves

An Assessment of Spatial and Temporal Variation in the Diet of Cape Clawless Otters (Aonyx capensis) in Marine Environments

Surfzone to inner‐shelf exchange estimated from dye tracer balances

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