Tidal Bore Dynamics Around the Similar Right-Angle Shoreline in the Qiantang Estuary, China

Tidal bores are a unique hydrodynamic phenomenon during flood tide in the Qiantang Estuary. The tidal bore propagation around the similar right-angle shoreline is rarely documented in tidal estuaries. To investigate tidal bores around this shoreline, a hydrodynamic model combined with a theoretical method is employed to reveal the characteristics of the bore propagation. The theoretical solution of the tidal bore intensity is deduced to illustrate the relationship of the incident tidal bores and the back-flow bores during the propagation. The hydrodynamic model based on shallow water equation is employed to perform the simulation of tidal bores in the estuary. Model results with respect to the bore height and the propagation speed of tidal bores have a favourable agreement with field data. The tidal bore dynamics in the neighborhood of the similar right-angle shoreline are elucidated. The characteristics of tidal bores in terms of water surface, velocity, bore steepness and the intensity are illustrated and the back-flow bore is analyzed by numerical and theoretical methods around the similar right-angle shoreline. The height of the back-flow bore relative to the incident tidal bore ranges from 1.05 to 1.77. Model result reveals that the ambient water depth and the shape of the similar right-angle shoreline are contributed to the back-flow bore formation.