A temporal waterline approach to mapping intertidal areas using X-band marine radar

Bell, Paul S.; Bird, Cai; Plater, Andy

doi:10.1016/j.coastaleng.2015.09.009

Cited by 58 publications

(53 citation statements)

References 50 publications

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“…The main limitation of the SED-sensors is that they take point measurements. Future studies could combine marine radar technology with SED-sensors to explore tidal flat dynamic equilibrium behaviours over larger scales while maintaining high monitoring resolution (Bell et al, 2016;Bird et al, 2017), and thus lead to improvements in current understanding of DET and morphological modelling.…”

Section: Direct Field Evidence Supporting Detmentioning

confidence: 99%

Dynamic equilibrium behaviour observed on two contrasting tidal flats from daily monitoring of bed-level changes

Wal

Cai

et al. 2018

Geomorphology

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Highlights: High-resolution field data supports dynamic equilibrium theory for tidal flats  Empirical Orthogonal Function analysis revealed dynamic equilibrium behaviour  Tide-induced bottom shear stress shown to regulate morphology of macrotidal systems  Lower sediment input may have induced the observed pattern of erosion Abstract Dynamic Equilibrium Theory (DET) has been applied to tidal flats to systematically explain intertidal morphological responses to various distributions of bed shear stress (BSS). However, it is difficult to verify this theory with field observations because of the discrepancy between the idealized conceptions of theory and the complex reality of intertidal dynamics. The core relation between intertidal morphodynamics and BSS distribution can be easily masked by noise in complex datasets, leading to conclusions of insufficient field evidence to support DET. In the current study, hydrodynamic and morphodynamic data were monitored daily for one year on two tidal flats with contrasting wave exposures. BSS distribution was obtained by validated numerical models. Tidal flat dynamic equilibrium behaviour and BSS were linked via Empirical Orthogonal Function (EOF) analysis. We show that the principal morphodynamic modes corresponded well with the respective modes of BSS found at both sites. Tide-induced BSS was the dominant force at both sites, regardless of the level of wave exposure. The overall erosional and steepening trend found at the two flats can be attributed to the prevailing action of tidal forcing and reduced sediment supply. Hence, EOF analysis confirmed that tidal flat morphodynamics are consistent with DET, providing both field and model evidence to support this theory.

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Section: Direct Field Evidence Supporting Detmentioning

confidence: 99%

Dynamic equilibrium behaviour observed on two contrasting tidal flats from daily monitoring of bed-level changes

Wal

Cai

et al. 2018

Geomorphology

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“…By averaging a sequence of images over a time period substantially longer than the period of the incident sea swell, clutter is removed, leaving patterns of enhanced wave dissipation that have been shown to correspond well to submerged sandbar or shoreline features (Holland, ; Holland et al, ; Holman et al, ; Lippmann et al, ; Lippmann & Holman, ; Pearre & Puleo, ; Pianca et al, ; Plant et al, ; Van Enckevort & Ruessink, , ). Likewise, instantaneous X‐band radar observations can be averaged over similar periods (e.g., several minutes) to produce maps of persistent high‐intensity regions that delineate inlet features (Bell et al, ; McNinch et al, ; Ruessink et al, ). Similar to the optical video technique (Lippmann & Holman, ; Van Enckevort & Ruessink, ), shoal locations can be estimated from the peak value of across‐shoal intensity.…”

Section: Observational Datamentioning

confidence: 99%

X‐Band Radar Mapping of Morphological Changes at a Dynamic Coastal Inlet

et al. 2018

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Remote sensing of the complex interactions between bathymetry, tidal flow, and waves in coastal inlets provides high‐resolution data sets that can be exploited to characterize the morphological variability of shallow ebb tidal deltas (ETD). Here we used observations from a mobile X‐band radar platform to determine optimal conditions during which radar‐derived shoal signatures best represent positions of underlying shoals. Significant increases in the spatial errors of radar shoal signatures were observed when offshore wave energy intensified. Consequently, the lowest spatial errors occurred when the radar shoal signatures were primarily a function of the tidal flow (i.e., low sea state). We used these findings to quantify shoal migration patterns at the New River Inlet, North Carolina. We found that the southwestern portion of the ETD had the largest morphological variability with typical shoreward migration rates of 2–3 m/day driven by incident wave energy. The migration rates and patterns estimated from X‐band observations were consistent with numerical modeling results and a previous video‐based New River remote sensing study. Our results confirm that X‐band radar can be used to quickly map shallow ETDs (e.g., 5 min of observations), allowing for rapid morphological assessments from shore or boat‐based platforms. The methods would prove particularly useful for initial assessment as well as continual monitoring of dynamic tidal inlets where large morphological responses can be rapidly assessed and used for geomorphological studies, and as decision aids for maritime or engineering operations.

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“…Temporal methods and spectral methods have been developed in parallel. X-band radar images can be used as well to infer shallow water bathymetry [256,257]. In the field, the accuracy of measurements was considerably improved by D-GPS and their acquisition time considerably reduced using quads in the intertidal zone and boats or scooters in the subtidal area.…”

Section: A Science Field That Evolves With Technologymentioning

confidence: 99%

“…Time series of sufficiently resolved spatial images (such as Landsat) are also increasingly used to monitor shoreline evolution [282][283][284][285][286][287]. Other methods using a lidar or X-band radar may be used [257,288]. Drones are also equipped with multi-or hyperspectral sensors to map water colour and water quality parameters at high definition [289].…”

Section: A Science Field That Evolves With Technologymentioning

confidence: 99%

Why and How Do We Study Sediment Transport? Focus on Coastal Zones and Ongoing Methods

Ouillon

2018

Water

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Scientific research on sediment dynamics in the coastal zone and along the littoral zone has evolved considerably over the last four decades. It benefits from a technological revolution that provides the community with cheaper or free tools for in situ study (e.g., sensors, gliders), remote sensing (satellite data, video cameras, drones) or modelling (open source models). These changes favour the transfer of developed methods to monitoring and management services. On the other hand, scientific research is increasingly targeted by public authorities towards finalized studies in relation to societal issues. Shoreline vulnerability is an object of concern that grows after each marine submersion or intense erosion event. Thus, during the last four decades, the production of knowledge on coastal sediment dynamics has evolved considerably, and is in tune with the needs of society. This editorial aims at synthesizing the current revolution in the scientific research related to coastal and littoral hydrosedimentary dynamics, putting into perspective connections between coasts and other geomorphological entities concerned by sediment transport, showing the links between many fragmented approaches of the topic, and introducing the papers published in the special issue of Water on "Sediment transport in coastal waters".

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A temporal waterline approach to mapping intertidal areas using X-band marine radar

Cited by 58 publications

References 50 publications

Dynamic equilibrium behaviour observed on two contrasting tidal flats from daily monitoring of bed-level changes

Dynamic equilibrium behaviour observed on two contrasting tidal flats from daily monitoring of bed-level changes

X‐Band Radar Mapping of Morphological Changes at a Dynamic Coastal Inlet

Why and How Do We Study Sediment Transport? Focus on Coastal Zones and Ongoing Methods

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