OBSERVATIONS OF LONGSHORE MIGRATION OF COASTAL FEATURES USING X-BAND RADAR AND ITS MODELING
Intertidal morphology was monitored continuously with an X-band radar at research pier HORS located in Hasaki, Japan facing Pacific Ocean. The horizontal extent of a radar image is approximately 5.6 km and hourly averaged radar images were processed to observe longshore distributions of shoreline and bar positions. Longshore mean shoreline positions and their variation for year 2005 and 2006 showed a seasonal change, which are almost consistent with the results of the shoreline positions extracted from the beach profile data along the pier and follows so-called beach-cycle. Pixel intensities along a longshore line close to shoreline and bar from every averaged echo image are stacked in time to visualize the longshore migration of shoreline and bar undulations. Migration speeds of the shoreline and bar were estimated by cross correlation analysis method and were compared with the longshore current speed measured at the pier. The results show that the migration speeds of the shoreline and bar were highly correlated with longshore current speeds and directions. Detailed process of longshore migration within June and July 2006 is analyzed. During this period, a periodic change in shoreline positions both in time and space were observed. Wave lengths of the wavy feature of the shoreline were estimated. The cross-shore mean profile and their fluctuation intensities for this period indicate that the largest morphological activity appears within the intertidal and surf zone and mainly induced by longshore sediment motion.
Elsayed M. Galal Satoshi Takewaka
Dept.of Eng. Mechanics and Energy, University of Tsukuba, 305-8573, Japan Mechanics and Energy, University of Tsukuba, 305-8573, Japan
国际会议
第四届亚太地区海岸会议(the Fourth International Conference on Asian and Pacific Coasts)
南京
英文
2007-09-21（万方平台首次上网日期，不代表论文的发表时间）