MORPHOLOGY AND DYNAMICS OF CRESCENTIC BAR SYSTEMS

V. Goldsmith, D. Bowman, K. Kiley, B. Burdick, Y. Mart, S. Sofer

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

Aerial photograph and field studies in the southeastern Mediterranean, involving bathymetric mapping, and concurrent and antecedent wave measurements, have been used to delineate the sequential development of crescentic bars and associated dynamics. The bar sequence includes multiple parallel or wavy bars, ridge and runnels, oblique/transverse bars, single crescentic and double crescentic bars, and occurs during a calming down of wave activity from 2.5 to 0.5 m waves. The concomitant wave data, including wave directions, energy spectrum, significant wave height, and length of the calm period, showed strong correlation with the bar stages. An increase in total bar occurrence during summer is related to a major wave energy decrease in the spring, when significant wave heights (H) < 1 m sharply increase to 70-85% in April-May. Inner single crescentic and initial double-crescentic bars are largely restricted to the calmest wave months of May/April to October/November, which reflects their sensitivity to wave energy. The aseasonal occurrence is best shown by the mature double crescentic type, which apparently is the final stage in the crescentic bar development sequence. Two bar developmental sequences were delineated: one shore-normal and the other initially oblique, but gradually rotating to shore-normal in the mature stage. Out of phase relationships between inner and outer bar systems resulted from the lag in response of the outer bars behind changes in wave direction. Among the inner crescentic bars and shore rhythms, phase-correlation was the rule. Crescentic bars are well developed on this coast because of the dissipative conditions and the distinct wave climate. High waves in the winter remove the existing bars, and extended calms allow the full development of the crescentic bar sequence. Similar bar types occur on different coasts in different sequences and in different proportions of time. Thus, it is suggested that these differences are attributable to global differences in the occurrences of threshold wave height conditions.

Original languageEnglish
Title of host publicationProceedings of the 18th Coastal Engineering Conferene
EditorsBilly L. Edge
PublisherAmerican Society of Civil Engineers (ASCE)
Pages941-953
Number of pages13
ISBN (Electronic)9780872623736
DOIs
StatePublished - 1982
Externally publishedYes
Event18th International Conference on Coastal Engineering - Cape Town, South Africa
Duration: 14 Nov 198219 Nov 1982

Publication series

NameProceedings of the Coastal Engineering Conference
Volume1
ISSN (Print)0161-3782

Conference

Conference18th International Conference on Coastal Engineering
Country/TerritorySouth Africa
CityCape Town
Period14/11/8219/11/82

Bibliographical note

Publisher Copyright:
© 1982 American Society of Civil Engineers (ASCE). All rights reserved.

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Ocean Engineering
  • Oceanography

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