Medium-term bar behavior and associated sediment transport at Hasaki, Japan

[1] The medium-term movement of a longshore bar and the associated cross-shore sediment transport were investigated using beach profile data obtained nearly daily for 8 years from the seaward foot of a dune to a water depth of about 5 m at Hazaki Oceanographical Research Station (HORS). Bar crests were found to move seaward repeatedly with a period of a year. The duration time of the seaward bar migration is shorter than those on the other coasts in the United States, the Netherlands, and New Zealand. Although bars migrated in one direction, seaward, the cross-shore sediment transport rate associated with the bar migrations fluctuated seaward and shoreward. Seaward sediment transport occurred on and around bar crests, whereas shoreward sediment transport occurred in trough regions. The cross-shore sediment transport was active when the offshore wave energy was large, from winter to spring and in autumn. However, the direction of the sediment transport in a region where bars were most developed was different during the two periods; it was seaward from winter to spring and shoreward in autumn. A numerical model for beach profile change confirmed that the development and decay of a bar was caused by the spatial and temporal variations of the cross-shore sediment transport rate.

[1]  Relationship between beach profiles and waves at Duck, North Carolina, determined by canonical correlation analysis , 2000 .

[2]  D. Bailey,et al.  A Review of Net Offshore Bar Migration with Photographic Illustrations from Wanganui, New Zealand , 1999 .

[3]  K. Katoh,et al.  Changes of Sand Grain Distribution in the Surf Zone , 1996 .

[4]  Edward B. Thornton,et al.  Bar/trough generation on a natural beach , 1996 .

[5]  Steve Elgar,et al.  Observations of sand bar evolution on a natural beach , 1998 .

[6]  B. G. Ruessink,et al.  The behaviour of nearshore bars on the time scale of years: a conceptual model , 2000 .

[7]  B. Greenwood,et al.  Equilibrium slopes and cross-shore velocity asymmetries in a storm-dominated, barred nearshore system , 1991 .

[8]  W. A. Birkemeier,et al.  Effects of CERC Research Pier on Nearshore Processes , 1991 .

[9]  David G. Aubrey,et al.  Seasonal patterns of onshore/offshore sediment movement , 1979 .

[10]  B. G. Ruessink,et al.  The behaviour of a multiple bar system in the nearshore zone of Terschelling, the Netherlands: 1965–1993 , 1994 .

[11]  Kathelijne Mariken Wijnberg,et al.  Extracting decadal morphological behaviour from high-resolution, long-term bathymetric surveys along the Holland coast using eigenfunction analysis , 1995 .

[12]  Donald G. Bailey,et al.  An Inter-Site Comparison of Net Offshore Bar Migration Characteristics and Environmental Conditions , 1999 .

[13]  A J Bowen,et al.  Simple Models of Nearshore Sedimentation, Beach Profiles and Longshore Bars , 1980 .

[14]  R. Holman,et al.  The spatial and temporal variability of sand bar morphology , 1990 .

[15]  A. Sallenger,et al.  Nearshore bars and the break-point hypothesis , 1989 .

[16]  N. Kraus,et al.  DYNAMICS OF LONGSHORE BARS , 1993 .

[17]  Nathaniel G. Plant,et al.  A simple model for interannual sandbar behavior , 1999 .

[18]  J. Horel.  Complex Principal Component Analysis: Theory and Examples , 1984 .

[19]  R. Holman,et al.  Storm-induced response of a nearshore-bar system , 1985 .

[20]  H. Storch,et al.  Statistical Analysis in Climate Research , 2000 .

[21]  D. Inman,et al.  Description of seasonal beach changes using empirical eigenfunctions , 1975 .

[22]  W. Birkemeier.  Time Scales of Nearshore Profile Changes , 1984 .