Lidar observations of the swash zone of a low-tide terraced tropical beach under variable wave conditions: The Nha Trang (Vietnam) COASTVAR experiment

Luís Pedro Almeida, Rafael Almar, Chris Blenkinsopp, Nadia Senechal, Erwin Bergsma, France Floc'h, Charles Caulet, Melanie Biausque, Patrick Marchesiello, Philippe Grandjean, Jerome Ammann, Rachid Benshila, Duong Hai Thuan, Paula Gomes da Silva, Nguyen Trung Viet

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

A field experiment was conducted at a tropical microtidal intermediate sandy beach with a low tide terrace (Nha Trang, Vietnam) to investigate the short-term swash-zone hydrodynamics and morphodynamics under variable wave conditions. Continuous 2D Lidar scanner observations of wave height at the lower foreshore, subsequent run-up and swash-induced topographic changes were obtained. These data were complemented by detailed real-time kinematic GPS topographic surveys. Variable wave and tide conditions were experienced during the field experiment with relatively large swell waves (offshore significant wave height, Hs = 0.9 m to 1.3 m; peak wave period, Tp = 8 to 12 s) concomitant with spring tides at the beginning of the period, followed by mild wind waves (offshore Hs under 0.5 m and Tp 5 s) and neap tides. This resulted in the following morphological sequence: berm erosion followed by rapid neap berm reformation and beach recovery within a few days. New insights into the link between intra-tidal swash dynamics and daily beach profile evolution were found using the Lidar dataset. While waves directly cause morphology changes on a wave-by-wave basis, tidal levels were found to be a key factor in determining the morphological wave-effect (accretive or erosive) due to modulated interaction between surf and swash hydro-morphodynamics.

Original languageEnglish
Article number302
JournalJournal of Marine Science and Engineering
Volume8
Issue number5
Early online date26 Apr 2020
DOIs
Publication statusPublished - 1 May 2020

Keywords

  • Lidar
  • Low-tide-terrace
  • Nha Trang-Vietnam
  • Swash zone
  • Tide

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Water Science and Technology
  • Ocean Engineering

Cite this

Almeida, L. P., Almar, R., Blenkinsopp, C., Senechal, N., Bergsma, E., Floc'h, F., Caulet, C., Biausque, M., Marchesiello, P., Grandjean, P., Ammann, J., Benshila, R., Thuan, D. H., da Silva, P. G., & Viet, N. T. (2020). Lidar observations of the swash zone of a low-tide terraced tropical beach under variable wave conditions: The Nha Trang (Vietnam) COASTVAR experiment. Journal of Marine Science and Engineering, 8(5), [302]. https://doi.org/10.3390/JMSE8050302