A Field Study on the Characteristics of Sand Bar Migration under Eroding Conditions

Abstract

Long-term variations of seabed profiles on Mikawa Coast, Japan, have been investigated using a set of field surveys collected over 46 years. The focus is placed on the migration of nearshore bars under the influence of severe erosion. The variation of the cross-shore bar locationi s examinedi n detail.I t is shown that the cross-shore periodicm ovements have been repeated several times with about 10-year cycles. Superimposed on periodical migration, the outer bar position has a clear onshore trend in longer time scale of decades. An attempt has been made to separate the eroding trend and periodic migration of bars by using a time-varying standard profiles. On the basis of the separated results, real type empirical orthogonal function analysis is conducted to effectively capture the characteristics of sand bar migrations