A Study on the Morphological Characteristics around Artificial Headlands in Kashima Coast, Japan

An, Shuqing; Takewaka, Satoshi

doi:10.2112/jcoastres-d-15-00122.1

Cited by 3 publications

(5 citation statements)

References 12 publications

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“…A horizontal and bright edge extending in the longshore corresponds to the shoreline, which is marked in Figure 3a; the radar position is located at the center of the bottom edge in the figure, indicated by a black oval. The time-averaged images enable the identification of the intertidal bathymetry, breaker zone, rip current, bar crest locations, mega-cusp migrations, wave run-up, and other features [6,26,27,[43][44][45]. Previously, Takewaka [6] examined the accuracy of the intertidal morphological feature using time-averaged images compared to field survey results.…”

Section: X-band Radar System and Time-averaged Imagesmentioning

confidence: 99%

“…Time-series of individual radar pixel intensities are gathered from hourly time-averaged images across the selected timescale of two weeks, including a full spring-neap cycle (as an example, June [17][18][19][20][21][22][23][24][25][26][27][28][29][30]2005). Figure 6a displays the cross-shore time stack images within the range between y = 5 m and y = 103 m. The red line marked in Figure 6b indicates the variation of the instantaneous waterline position digitized manually by visual inspection, and Figure 6c is the concurrent tidal records.…”

Section: Intertidal Beach Profile and Shoreline Estimation Using Twm mentioning

confidence: 99%

“…The most significant advantage of shoreline monitoring with X-band radar is that it can provide real-time and uninterrupted observations even in bad weather conditions. Since the last two decades, land-based remote sensing monitoring systems such as X-band radar have become popular in coastal studies [6,[25][26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

“…The pixel intensities over two weeks(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) June 2005) at 49 m and (a) 22 m, (b) 27.5 m, (c) 33 m, and (d) 38 m. (e) The tidal binary signal indicating above or below water level −0.2 m: (f) water level 0.0 m and (g) water level 0.2 m. The tables on the right-hand side of a-g illustrate the correlation coefficients between the pixel intensity variation and tidal binary signals. Higher correlation values show strong similarities between pixel intensity variation and binary signal representation of tide records.…”

mentioning

confidence: 99%

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Automatic Shoreline Position and Intertidal Foreshore Slope Detection from X-Band Radar Images Using Modified Temporal Waterline Method with Corrected Wave Run-up

Kumar

Takewaka

2019

JMSE

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Automatic and accurate shoreline position and intertidal foreshore slope detection are challenging and significantly important for coastal dynamics. In the present study, a time series shoreline position and intertidal foreshore slope have been automatically detected using modified Temporal Waterline Method (mTWM) from time-averaged X-band radar images captured throughout the course of two-week tidal cycle variation over an area spanning 5.6 km on the Hasaki coast between 12 April 2005 and 31 December 2008. The methodology is based on the correlation map between the pixel intensity variation of the time-averaged X-band radar images and the binary signal of the tide level ranging from −0.8 m to 0.8 m. In order to ensure the binary signal represented each of the water levels in the intertidal shore profile, determining the water level direction-wise bottom elevation is considered as the modification. Random gaps were detected in the captured images owing to the unclear or oversaturation of the waterline signal. A horizontal shift in the detected shoreline positions was observed compared to the survey data previously collected at Hasaki Oceanographical Research Station (HORS). This horizontal shift can be attributed to wave breaking and high wave conditions. Wave set-up and run-up are the effects of wave breaking and high wave conditions, respectively. The correction of the wave set-up and run-up is considered to allow the upward shift of the water level position, as well as shoreline position, to the landward direction. The findings indicate that the shoreline positions derived by mTWM with the corrected wave run-up reasonably agree with the survey data. The mean absolute bias (MAB) between the survey data and the shoreline positions detected using mTWM with the corrected wave run-up is approximately 5.9 m, which is theoretically smaller than the spatial resolution of the radar measurements. The random gaps in the mTWM-derived shoreline positions are filled by Garcia’s data filling algorithm which is a Penalized Least Squares regression method by means of the Discrete Cosine Transform (PLS-DCT). The MAB between survey data and the gap filled shoreline positions detected using TWM with corrected wave run-up is approximately 5.9 m. The obtained results indicate the accuracy of the mTWM with corrected wave run-up integrated with Garcia’s method compared to the survey observations. The executed approach in this study is considered as an efficient and robust tool to automatically detect shoreline positions and intertidal foreshore slopes extracted from X-band radar images with the consideration of wave run-up correction.

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Section: X-band Radar System and Time-averaged Imagesmentioning

confidence: 99%

Section: Intertidal Beach Profile and Shoreline Estimation Using Twm mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Automatic Shoreline Position and Intertidal Foreshore Slope Detection from X-Band Radar Images Using Modified Temporal Waterline Method with Corrected Wave Run-up

Kumar

Takewaka

2019

JMSE

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“…More recently, Troselj et al (2018) and Troselj et al (2019) conducted dynamical downscaling of coastal dynamics emphasizing freshwater impact from three major rivers and seasonal variabilities of SST and SSS, respectively. Furthermore, several past studies focused on shoreline variabilities along the Ibaraki Coast Galal, 2007, 2015;Suzuki and Kuriyama, 2014;An, 2016;Banno et al, 2016;Takewaka and Wen, 2017), with some of them dealing with impacts due to the October 2006 storms. Galal and Takewaka (2011) conducted erosion analyzes along the Kashima Coast in Ibaraki for the extreme October 2006 storm from the viewpoint of wave energy flux distribution.…”

Section: Introductionmentioning

confidence: 99%

Dynamical Downscaling of Coastal Dynamics for Two Extreme Storm Surge Events in Japan

et al. 2021

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Nearshore Current Pattern and Rip Current Occurrence at Jungmun Beach, Jeju by Numerical Computation

An¹,

Kim²

2017

JNPR

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: A nearshore current or a wave-induced current is an important phenomenon in a nearshore zone, which is composed of longshore, cross-shore, and rip currents. The nearshore current is closely related to the occurrence of coastal accidents by beachgoers. A considerable number of coastal accidents by beachgoers involving the rip current have been reported at Jungmun Beach. However, in studies and observations of the nearshore current of Jungmun Beach, understanding of the rip current pattern remains unclear. In this study, a scientific approach is taken to understand the nearshore current and the rip current patterns at Jungmun Beach by numerical computation for year of 2015. From results of numerical computation, the occurrence and spatial characteristics of the rip current, and the similarities between the rip current and incident wave conditions are analyzed. The primary results of this study reveal that the rip currents are frequently generated at Jungmun Beach, especially in the western parts of the beach, and that the rip currents often occur with a wave breaking height of around 0. 5~0.7 m, a wave period of around 6~8 seconds, and a breaking angle of around 0~15 degrees.

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A Study on the Morphological Characteristics around Artificial Headlands in Kashima Coast, Japan

Cited by 3 publications

References 12 publications

Automatic Shoreline Position and Intertidal Foreshore Slope Detection from X-Band Radar Images Using Modified Temporal Waterline Method with Corrected Wave Run-up

Automatic Shoreline Position and Intertidal Foreshore Slope Detection from X-Band Radar Images Using Modified Temporal Waterline Method with Corrected Wave Run-up

Dynamical Downscaling of Coastal Dynamics for Two Extreme Storm Surge Events in Japan

Nearshore Current Pattern and Rip Current Occurrence at Jungmun Beach, Jeju by Numerical Computation

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