Modeling the morphodynamic response of a large tidal channel system to the large-scale embankment in the Hangzhou Bay, China

Abstract

A large tidal channel has developed along the northern shore of the Hangzhou Bay. Its length and width are about 50 and 10 km, respectively. It serves as an important navigation channel and provides port construction locations. This contribution investigates the morphological response of the tidal channel to the large-scale embankment in recent decades and the physical mechanisms, based on an idealized 2D morphodynamic model. The tidal channel was reproduced within a timescale of several years, with spatial scales comparable to the real situation. The results showed that the macroscopic sediment transport pattern in the bay, namely, entering in the north and leaving in the south, was not changed by the embankment. The tidal range and sediment flux increased to a certain extent, because of the decrease of the cross-sectional width. Meanwhile, the longitudinal gradient of the residual sediment transport enlarged slightly. As a result, the tidal channel was eroded significantly, because of the nonlinear interaction among hydrodynamics, sediment transport, and morphological change. Furthermore, there are inherent connections among the main morphological features in the bay. Complementary to other approaches, this model provides a useful tool to predict the morphodynamic behavior for the estuarine planning and regulations.