Sandy barriers comprise 12% of coastlines around the world, and most of these barriers enclose tidal bays and lagoons. These systems accommodate human settlements vulnerable to climate change, which offer enough economic, social, and environmental utility to require further research on the impact of climate change and subsequent best management practices.

The present work aims to analyze how climate change impacts the hydrodynamics and morphodynamics of two barrier inlet systems: Katama Bay (United States of America), and the Santa Lucia Estuary (South Africa). The goal is to estimate future changes in forcing variables (e.g., sea level rise, wave climate, river discharge, tides), implement them in process-based models (coupled SWAN and Delft3D), and identify changes in the dynamics of both systems by comparing present and future state simulations.

This thesis develops a replicable and flexible methodology that can be used as a systematic tool to assess the impacts of climate change on the overall dynamics of tidal inlet systems. A novel approach (copula analysis) was used to derive the wave climate implemented in Delft3D, which was then qualitatively validated for both sites. Model results were used to compare changes to inlet stability, inlet geometry, and sediment pathways for present and future hydrodynamic conditions.

Results show that sea level rise is the primary contributor to the overall morphodynamics at both sites, whereas changes in wave direction strongly impact the rate of inlet migration. Other changes (e.g., significant wave height, wave period, and river discharge) play a secondary role in the dynamics of both systems. Comparisons with previous studies suggest that wave direction impacts each system differently. These impacts must be specifically addressed for each tidal inlet, as the results from one site should not be used to determine a general behavior for the assessment of CC impacts in tidal inlet systems.

The climate goals for 2020, that multiple countries in the world signed, are coming closer. Like many other countries, the Netherlands has difficulties reaching their climate goal. A solution came from the Paris agreement in 2015, which sets new goals for 2030, and eventually for the long term in 2050. This time the Netherlands is eager to reach their goal and amongst many other initiatives, a proposition came from TenneT, the country’s national energy operator, to construct an island in the North Sea, functioning as a central “wind connector hub” to connect multiple offshore wind farms and distributing the energy more efficiently over the neighbouring countries. The goal of the project is to propose and analyse a preliminary design for the construction of that artificial island in the North Sea, capable of acting as a central energy hub. An analysis for optimum location for the island was performed based on maximum wind generation, shallow water depths, centrality to the North Sea countries, and environmental restrictions. Of various types of island considered, the reclamation type was chosen for preliminary design because it is the most cost effective for the location’s water depths and the most commonly constructed island type. Following the scope definition, correspondence with TenneT and consultancy with subject experts at TU Delft was made to refine preliminary design outcomes. The preliminary design covers the analysis of available environmental and geotechnical data, safety approach, island shape, zones, elevations, analysis of alternative sea defence structures, building with nature measures, port and terminal design, and preliminary construction plan. The conclusions of this investigation cover practical issues, project risks and uncertainties, and opportunities to reduce costs are discussed.