Low-Cost Handheld Global Positioning System for Measuring Surf-Zone Currents

MacMahan, Jamie; Brown, Jeff; Thornton, Edward B.

doi:10.2112/08-1000.1

Cited by 80 publications

(66 citation statements)

References 10 publications

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“…Rip drifter floats were constructed following a design similar to Schmit et al (2003) and their position was monitored at 0.5 Hz using GPS loggers that were post-processed from a survey-grade static base station following MacMahan et al (2009). These provided estimates of rip current flows with an accuracy for position and speed of o 0:4 m and o 0:01 m s À1 , respectively.…”

Section: Field Methods and Instrumentationmentioning

confidence: 99%

Temporal observations of rip current circulation on a macro-tidal beach

Austin

Scott

Brown

et al. 2010

Continental Shelf Research

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108

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Section: Field Methods and Instrumentationmentioning

confidence: 99%

Temporal observations of rip current circulation on a macro-tidal beach

Austin

Scott

Brown

et al. 2010

Continental Shelf Research

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108

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“…The cost and design of these drifters varies depending on the application. Building on deployments of drifters in the deep ocean (e.g., Davis 1985), and taking advantage of cheap and accurate modern GPS systems, researchers have recently developed low-cost drifters for use in nearshore, estuarine (Johnson et al 2003;Austin and Atkinson 2004;Thomson 2012) and surfzone (Schmidt et al 2003;MacMahan et al 2009) environments. However, the drifter designs above typically have drafts of around 0.5 to 1 m, rendering them unsuitable for use in very shallow flows.…”

mentioning

confidence: 99%

A novel drifter designed for use with a mounted Acoustic Doppler Current Profiler in shallow environments

Mullarney

Henderson

2013

Limnology & Ocean Methods

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Lagrangian drifters have been used for many years to measure surface currents over a wide range of spatial and temporal scales. The cost and design of these drifters varies depending on the application. Building on deployments of drifters in the deep ocean (e.g., Davis 1985), and taking advantage of cheap and accurate modern GPS systems, researchers have recently developed low-cost drifters for use in nearshore, estuarine (Johnson et al. 2003;Austin and Atkinson 2004;Thomson 2012) and surfzone (Schmidt et al. 2003;MacMahan et al. 2009) environments. However, the drifter designs above typically have drafts of around 0.5 to 1 m, rendering them unsuitable for use in very shallow flows.Modern compact Acoustic Doppler Current Profilers (ADCPs) are capable of measuring velocities over range bins of a few centimeters. The small size, high resolution, and short blanking distance of these instruments have raised the possibility of using drifter-mounted ADCPs to resolve near-surface flows, even in very shallow environments.We present a novel design for surface drifters intended for use with a Nortek Aquadopp ADCP. The design yielded highresolution vertical profiles of velocity, as the drifter tracked the propagation of baroclinic surface fronts over very shallow tidal flats (water depths of 0.2-1 m). The highest bin of the velocity profiles was around just 0.18 m below the water surface, a notable improvement over use of majority of the above designs, which would result in a smallest measurement depth of around 0.62 m below the surface (based on a representative 0.5 m drifter draft plus 0.07 m ADCP draft plus 0.05 m blanking distance). The Thomson (2012) drifter used an uplooking ADCP, which allowed measurements to be made close to the water surface; however, the drifter had a 1.25 m draft preventing its deployment in very shallow water depths. For water depths of between 0.15 m and 0.18 m, the ADCP-mounted drifter described here was still freely advected, but in this case, ADCP measurements were not obtained. The drifters were robust and of very simple construction, requiring only use of hand tools and using off-the-shelf components. Although the cost of the ADCP was substantial (exceeding US$10,000), the cost for each drifter body was minimal (less than US$100, similar to costs of the other drifters above). Drifter positions were tracked by an inexpensive off-the-shelf GPS logger (

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“…This data was analysed to understand the characteristics of these flow patterns and their dependence on the present hydrodynamic conditions and the underlying bathymetry. Lagrangian velocities in the surf zone were measured with drifter instruments following the design described in MacMahan et al (2009). Throughout the field experiment six measurement sessions were conducted under various wave, wind and tidal conditions, each consisting of four to five drifter deployments.…”

Section: Methods and Conditionsmentioning

confidence: 99%

A Field and Numerical Study Into Rip Currents in Wind-Sea Dominated Environments

Winter

Dongeren

Schipper

et al. 2012

Int. Conf. Coastal. Eng.

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Rip currents are wave-induced and off-shore directed flows which occur frequently in the surf zone and can pose a serious threat to swimmers. While the behaviour of rip currents has been studied in swell-dominated environments, less is known about their characteristics in wind-sea dominated environments. This study aims to improve the knowledge on rip currents in these environments such as the Dutch coast. In a field campaign at Egmond aan Zee (The Netherlands), Lagrangian velocities in the surf zone were measured with drifter floats. An extensive dataset of rip current measurements was collected from which parameters that initiate rip currents and affect their mean flow properties were identified. Numerical simulations with XBeach aided to understand and confirm the observations made in the field. A reduction of the hydrodynamic parameters along with simplification of the bathymetry in the model allowed for identification of the governing rip current parameters, which can be the basis for a warning system.

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Low-Cost Handheld Global Positioning System for Measuring Surf-Zone Currents

Cited by 80 publications

References 10 publications

Temporal observations of rip current circulation on a macro-tidal beach

Temporal observations of rip current circulation on a macro-tidal beach

A novel drifter designed for use with a mounted Acoustic Doppler Current Profiler in shallow environments

A Field and Numerical Study Into Rip Currents in Wind-Sea Dominated Environments

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