LONGSHORE MIGRATION OF SHORELINE MEGA-CUSPS OBSERVED WITH X-BAND RADAR

概要

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Intertidal morphology was monitored continuously with an X-band radar at the researchpier HORS in Hasaki, Japan. Hourly-averaged radar images were processed to observe longshoredistributions of shoreline positions. Variations of longshore mean shoreline positionsand their fluctuation intensities observed in the years 2005 and 2006 showed a seasonalchange which followed the so-called beach-cycle. Longshore pixel intensities close to thewaterline were extracted from time-averaged images for every hour of the two years toprocess longshore time-stack image. Longshore migration speeds of shoreline mega-cuspswere estimated by cross correlation analysis of the time-stack image, and the reliability ofthe method was checked. Migration speeds were compared to measured longshore currentspeeds at the pier and the longshore component of the wave power, showing that theyare highly synchronized for most conditions. Finally, the migration statistics were relatedto the wave data, and the results showed that the northwards migration rates were typicallylarger than southwards rates, which was consistent with the statistical results forwave forcing variables. Also, the relationship between the migration speeds and the forcingvariables indicates that the migration was more active when the wave incidence angle wasclose to 45◦.
World Scientificの論文
2008-09-01