Laboratory study on wave-induced setup and wave-driven current in a 2DH reef-lagoon-channel system

Abstract

The nearshore wave action at many barrier reefs or reef atolls can generate wave setup and drive a 2DH reef-lagoon-channel circulation. Previous laboratory studies on such reef-lagoon-channel system focused mainly on the 1DH wave-flume experiments without considering the alongshore wave dynamics. To better understand the wave-induced setup and wave-driven current in a reef-lagoon-channel system, a series of laboratory experiments are conducted in a wave basin based on an idealized physical model subject to both regular and irregular waves. Both the cross-shore and alongshore variations of wave setup and mean current are analyzed, and the influences of incident wave height, wave period and reef-flat water level on these wave processes are examined. A dimensionless analysis of both wave setup and mean current on the reef flat is conducted and the results are compared with other published laboratory data. A quasi-2DH analytical model is improved by incorporating the alongshore wave dynamics in the lagoon to reproduce the present experimental observation. The dominant circulation pattern in the system is identified with the analytical model.