Study Of Wave Transformation And Wave-driven Circulation Over Reef-Lagoon-Channel Systems

Coral reefs are widely distributed in tropical and subtropical shallow sea which not only bring rich ecological and tourism resources to human beings,but also have important coastal protection functions.The research about wave transformation and wave-driven circulation over reef-lagoon-channel systems is not only of great scientific significance for coral reef hydrodynamics,but also providing the reference for the reef development,utilization and protection.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 have been conducted in a wave basin based on an idealized physical model subject to both regular and irregular waves.The wave height distribution and wave spectrum evolution on the reef flat as well as wave run-up on the back-reef slope are first analyzed,and the impacts of incident wave height,wave period and reef-flat wave level on these wave processes are investigated.The excitation of resonant modes is identified to account for the infragravity(IG)wave characteristics in the system.Then,both 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 wave 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.