Estuarine shoals are valuable areas with functions of nature, safety and navigation. It is of utmost importance to understand their underlying physical processes and long-term evolution to achieve protection. The first aim of this report is to determine the impact of wind-waves on long-term morphological development of estuarine shoals. The rapid sea level rise requires a valid model prediction of esturine shoal evolution in the future. Whether waves should be included for forecast needs to be evaluated. This rises the second aim to investigate wind-waves impact on estuarine shoals evolution under the sea level rise. A 2-D, process-based numerical model (Delft3D) is applied. This study sets up a large scale realistic model covering the whole Western Scheldt geometry and focuses on shoal Van Ossenisse by constructing high resolution grids and imposing wind-waves. Simulations are compared on a timescale of 50 years, with and without wave effects. Results revels that waves tend to slightly migrate shoals along their propagation direction. Waves erode sediment in the intertidal area, resulting in a lowering elevation of the shoal and high suspended sediment concentrations in water column. On the one hand, high SSC combined with wave asymmetry and wind-driven flow enhance sediment transport rate along wave propagation direction over top of the shoal, causing more sediment appearing in the lee side of the shoal. On the other hand, wave-induced suspended sediment follows tidal currents and transport to shoal edges where low bed shear stress exists. These cause shoal widening at lower intertidal area and upper subtidal area. Channel velocity hence increases with response to channel area reduction. This leads to erosion in the channel and channel deepening. In a longer timescale, waves impact do not lead to fundamental difference on estuarine autonomous behaviors. It reveals that waves impact may be sensitive to some parameters (eg. sediment grain size, tidal range, type of boundary conditions), especially in the inner channel. It is recommended to do more investigations. Sea level rise scenarios are carried out by imposing gradually sea level rise at the seaward boundary. Its timescale is 100 years. Both in wave and no wave case, sea level rise leads to elevation of shoal height and area lose in shoal edges, resulting in steeper slope in the intertidal area. Larger channel area and volume are presented with sea level rise. Waves maintain their function under the sea level rise. It lowers and widens the shoal, resulting in the increase of intertidal area and volume. Sea level rise does not change the tendency of waves impact. ... Read more

The report starts in Chapter 1 with an introduction to the Sponge City Programme (SCP) in China and the project area which is the ErQi International Business District in Wuhan. In this chapter, the problem statement, our collaboration with Arcadis and our project goals are also introduced. Chapter 2 delves into our methodology to tackle the brief. Starting from how we shaped our interdisciplinary approach, we explain our approach towards the project and our decision to include resiliency with the Sponge City concept as an objective. We continue by providing background information on ErQi area in Chapter 3 to get an overall understanding of the planned urban design and potential urban flooding. To provide a thorough analysis and recommendations for the selection process of adaptation measures to mitigate excess rainfall as part of the SCP in the context of ErQi area, an assessment of the Wuhan Sponge City criteria, a stakeholder analysis complemented by a spatial assessment was performed and described in Chapter 4. Setting the context allows understanding the complexity of the system and its constraints in the implementation of the SCP. Thus, we decided to first focus on the implementation of low-impact development (LID) measures using a multi-criteria analysis (MCA) presented in Chapter 4 and then developed an integrated and resilient system design later in the report. As the Sponge City is not sufficient to cope with high precipitation events (Arcadis, 2017), the project combines sponge city and resiliency principles in an integrated system approach.
The guiding resilient design principles of the Sponge City are further described and explained in Chapter 5 and applied in the opportunistic design process in Chapter 6, bridging the research with the designs. Here the designs of the MengQiao Bridge and the Water Road are presented along with their proposed effects on the urban flooding. Chapter 7 serves to assess the designs through the criteria of the integrated sponge city to improve flood resilience. The following chapter serves to share our conclusions on the challenges for implementing a functioning of the SCP that includes the concept of resilience. It also touches upon the difficulty of implementing the value-based design in a profit-based context. The final chapter is composed of five parts, all of which is our recommendations. It starts with our recommendations to improve the Sponge City criteria to make them more effective in reaching the goals of the programme. Then we give our recommendations for the selection process of LID followed by what we have learned of this interdisciplinary approach. That includes what we consider to be crucial to achieving a genuinely interdisciplinary process resulting in an integrated design. The final part of the chapter is dedicated to what we believe should be researched further. We believe a more in-depth assessment of the designs with the Sponge City criteria and input of the stakeholders is required for a final design. Further, the working definitions and approach of the Wuhan city government need to be considered, and an approach that assesses the necessary maintenance protocols is necessary.
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