Author(s): Huayang Cai; Hubert H. G. Savenije; Kees Kuijper
Linked Author(s):
Keywords: Scheldt estuary; Deepening; Tidal dynamics; Analytical solution; Asymptotic
Abstract: Over the last century the main navigational channel to the port of Antwerp was deepened several times. Furthermore, dumping and sand mining strategies changed over the years. The morphological changes resulted in larger channel depths which enhanced tidal amplification along the Scheldt estuary with negative impacts on safety and the environment. Hence it is important to understand the relationship between deepening and tidal amplification. In this study, a hybrid analytical model is used to investigate the effect of depth variation on tidal dynamics in the Scheldt estuary. For given geometry, friction and tidal amplitude at seaward boundary, we are able to reproduce the main tidal dynamics (e. g., velocity amplitude, wave celerity, tidal damping and phase lag between high water and high water slack) along the estuary axis. It is generally accepted that the tidal wave is further amplified as a result of the reduced friction induced by larger depth. However, we found that the Scheldt becomes over-amplified when it has a depth larger than the critical depth (condition for maximum amplification). In this case, a further increase of the depth reduces the tidal wave amplification until a frictionless standing wave system is reached asymptotically, where the tidal dynamics is completely determined by the convergence alone.
Year: 2013