Applicability of suspended sediment concentration formulae to large-scale beach morphological changes

Ravindra Jayaratne, Yasufumi Takayama, Tomoya Shibayama

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Study of beach morphological changes under storm conditions and its prediction capability are of paramount importance in coastal zone management. Seabed sediment is picked up violently in and outside the surf zone due to suspension mechanisms, therefore a considerable amount of sand is transported in coastal waters due to such mechanisms. For the construction of an accurate beach morphological model, it is necessary to elucidate the sediment suspension and to introduce it properly into the modelling of sediment transport. Jayaratne and Shibayama (2007) developed a complete set of explicit theoretical formulae to predict the time-averaged concentration on sandy beaches due to three suspension mechanisms: a) vortical motion over wave-generated sand ripples, b) from sheet flow, and c) turbulent motion under breaking waves. The present paper focuses on the development of a quasi-3D beach deformation model using the sediment concentration models of Jayaratne and Shibayama (2007), the bed load model of Watanabe (1982), the wave propagation model of Onaka et al. (1988), the nearshore current model of Philips (1977) and the undertow model of Okayasu et al. (1990) to predict the large-scale morphodynamics of sandy beaches. The predicted beach profiles and total sediment transport rates were compared with two sets of large-scale laboratory experimental data [Kajima et al. (1983); Kraus and Larson (1988)] and Seisho beach at Kanagawa Prefecture, Japan. It can be concluded that the present numerical model is capable of predicting sediment transport direction, on-offshore sand bar formation and the general trend of the beach profiles of large-scale erosive- and accretive-type sandy beaches to a satisfactory level.

Original languageEnglish
Title of host publicationProceedings of the 33rd International Conference on Coastal Engineering 2012, ICCE 2012
Publication statusPublished - 2012 Dec 1
Event33rd International Conference on Coastal Engineering 2012, ICCE 2012 - Santander, Spain
Duration: 2012 Jul 12012 Jul 6

Publication series

NameProceedings of the Coastal Engineering Conference

Conference

Conference33rd International Conference on Coastal Engineering 2012, ICCE 2012
CountrySpain
CitySantander
Period12/7/112/7/6

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Keywords

  • Breaking waves
  • Large-scale beach morphological changes
  • Quasi-3D beach deformation model
  • Sediment concentration
  • Sediment suspension
  • Sheet flow
  • Wave-generated sand ripples

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Ocean Engineering
  • Oceanography

Cite this

Jayaratne, R., Takayama, Y., & Shibayama, T. (2012). Applicability of suspended sediment concentration formulae to large-scale beach morphological changes. In Proceedings of the 33rd International Conference on Coastal Engineering 2012, ICCE 2012 (Proceedings of the Coastal Engineering Conference).