Simulating the impacts of land reclamation and de-reclamation on the morphodynamics of tidal networks

Abstract

The morphodynamic responses of tidal networks to anthropogenic reclamation and de-reclamation projects are investigated through a three-stage numerical simulation. In the first stage, the natural development of tidal networks is modelled in an open coast without any anthropogenic interventions. At the beginning of the second stage, parts of the computational domain are enclosed by sea dikes, which represents the implementation of the reclamation project. These sea dikes are removed or opened in the third stage to simulate the recovery of the tidal networks after de-reclamation. Each stage was set to last 100 years. The model results indicate that land reclamation can lead to three effects on tidal network morphology: (i) completely terminating the development of channels inside the projected area, (ii) hindering the development of the channel network in front of the dikes, and (iii) turning the channel direction near the corners of the dikes. When removing all the sea dikes, the previously reclaimed areas are quickly occupied by tidal networks. However, the morphology cannot be fully restored to its original natural state, although the entire reclaimed areas are returned. The effects of opening breaches are relatively slow, and tree-like network structures are formed inside the reclaimed areas.

Marine environment numerical simulation of morphological planning of land reclamation

“…Scientific input in the morphological planning and design of artificial islands can greatly reduce the damage to the surrounding Marine environment. [23][24][25][26] Therefore, in this study, EFDC model was used to simulate the water environment of different artificial island shapes, the size of the inner lake outlet and the layout of the artificial island, and recorded the water regime during the period of fast rising, high tide, fast ebb and low tide. By comparing and summarizing the variation law of Marine environment under various morphological design, the optimal scheme under three morphological design schemes was proposed to reduce the damage of Marine water environment caused by reclamation engineering…”

“…22 However, it is seldom used in Marine water research in China,. it has not been clear how to carry out the reclamation morphological design, 23 and lacks a set of morphological design criteria. Scientific input in the morphological planning and design of artificial islands can greatly reduce the damage to the surrounding Marine environment.…”

“…Scientific input in the morphological planning and design of artificial islands can greatly reduce the damage to the surrounding Marine environment. 23–26…”

Managing dyke retreat: Importance of century‐scale channel network evolution on storm surge modification over salt marshes under rising sea levels

“…Recent studies demonstrate that tidal channel networks quickly develop in de‐reclaimed land (DL) created when sea dykes are removed or retreated (Chen et al, 2020). Once developed, tidal channels act as a drainage pathway (Fagherazzi et al, 1999; Zhou et al, 2014), promoting marsh evolution and flood propagation through the salt marsh.…”

“…In particular: (i) the DL is represented by an unchannelized vegetated area, thus neglecting the evolution of the channel network; (ii) a spatially uniform vertical translation of marshes and channels simulates their morphological changes; (iii) the model does not simulate surge events with various duration, but only with various high-water levels (HWLs). To our knowledge, only a recent study simulates the long-term evolution of a salt marsh after dyke retreat (Chen et al, 2020). However, in that study, the model (i) omits bank erosion and wave impact when it computes the evolution of the salt marsh, and (ii) does not consider the presence of marsh vegetation, which increases friction and enhances sediment trapping.…”