Effect of tidal range on longshore current variation with respect to cross-shore location of a barred beach

ABSTRACT

Longshore and cross-shore currents in the surf zone were observed on a dissipative barred beach for 20 days using a horizontally mounted acoustic-Doppler current profiler (H-ADCP). This novel deployment strategy allowed for the synoptic measurement of the longshore current at approximately mid-depth at several cross-shore locations. The longshore current data were analyzed with wave and tide level data to show the effect of tidal range on the variation of the longshore current with respect to cross-shore location. The longshore current was higher near the outer bar area than that observed near the inner bar. Moreover, the current became higher during the low tide and lower during the high tide. A longshore current model was proposed using the spring and neap tide data sets and then applied to the remaining observation period during large events of incident wave energy flux. The model with the relative water level luded provided sufficient accuracy to account for the tide effects.

KEYWORDS:

• Field observation
• spring and neap tides
• h-ADCP
• cross-shore distributions

Acknowledgments

This work was funded under the JSPS Grant-in-aids No. 26709034 and No. 15KK0202. The authors would like to thank the Coastal and Estuarine Sediment Dynamics Group, Port and Airport Research Institute (PARI), for the use of their facility and the observed data of HORS. The authors also thank the Marine Information Group, PARI, and the Kashima Port and Airport Construction Office for allowing the use of offshore wave data. Furthermore, the authors would like to thank Prof. Yoshiyuki Nakamura and Dr. Hiroto Higa of Yokohama National University for their helpful comments, and specially thank Mr. Yu Inami, Dr. Masayuki Banno and Mr. Shinichi Yanagishima for their contribution to the field observation.

Disclosure Statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Japan Society for the Promotion of Science [15KK0202];Japan Society for the Promotion of Science [26709034].