INLET MORPHOLOGY AND TIDAL ASYMMETRY FOR AN UNSTABLE INLETSYSTEM

摘要

The Zwin Inlet, the Netherlands is a very dynamic but degrading inlet system due to thernannual import of significant amounts of sediment. The net import of sediment is a direct result of thernexistence of both a maximum flow asymmetry as well as a time-flow asymmetry in the inlet channel;rnthey both demonstrate a flood-dominated character. However, whereas the maximum flowrnasymmetry is strongly related to the offshore tidal conditions in the southern bight of the North Sea,rnthe time-flow asymmetry owes its existence to a morphological threshold in the inlet system. It leadsrnto a truncation of the early parts of the flood and implies a rapid acceleration of the flood current asrnsoon as the tidal wave is able to enter the inlet channel. Measurements and computations with thernVan Rijn sand transport model clearly show that most of the coarse-grained sediment transport isrnrealized for spring tide conditions, with suspended load being the dominant mode.