The use of the North Sea has transitioned into an intensely used industrial area, with the climate agreement as a driving force. The Paris agreement demands countries to change their main energy resources from oil, coal and gas to renewable resources such as wind. The Dutch government chose to use the space offshore for the development of wind farms. These developments require a durable collaboration between the various stakeholders in the North Sea. Tensions exist between the different stakeholders in the North Sea, and the projected developments are expected to pressure these relationships even further. The need for shared multi-use areas grows as the North Sea is used more and more intensely. This report presents a multidisciplinary design for an artificially enhanced fisheries system within an offshore wind farm (OWF). The goal of this design is to provide a nature inclusive solution to increasing pressure on the fishing industry by the growing offshore wind sector. The possible implementation of a fishing industry within OWFs was analysed. This resulted in a number of applicable solution spaces. A notable solution was the Fish-as-a-Service concept, which resolves several issues that currently hinder the development of multi-purpose OWFs. In this solution, a company would fulfil the role of managing the fisheries in OWFs without the need for wind farm clients to actively partake in the fishing industry. Five target species were selected that could be harvested from an artificial reef system within an OWF. These species were European lobster, Brown crab, Atlantic cod, European seabass and Cuttlefish. The selection of these species was made based on economic interest, ecological interest, the potential for non-intrusive fishing methods and previous successes in other studies and/or projects. These species formed the basis of further ecological and financial examinations. Based on the biological and technical criteria following from the stakeholder and biological analysis, the most suitable wind farm site where an artificially enhanced fishing area could be implemented was selected. It was concluded that the Borssele Wind Farm Zones 1 and 2 would be the most suitable sites. The bathymetry, soil conditions, seabed dynamics and metocean data were further analysed in order to create a design for the artificial reef. A range of possible reef concepts were developed, including loose rock revetment, placed block revetment, layer cakes, biohuts, block reefs, layered pipes, shipwrecks and decommissioned oil or gas platforms. These concepts were verified for their operability and whether they met the requirements for bio-enhanced fisheries. Three preliminary designs for an artificial reef system in the Borssele OWF were made based on these reef concepts and the circumstances at the site. Of these designs, the most desirable one includes block reefs, natural stones, layer cakes, decommissioned oil or gas platforms and shipwrecks in order to promote biodiversity and yield as much biomass as possible. An Ecopath with Ecosim model was designed using available literature studies. This model was used to predict the amount of biomass produced in an OWF with and without hard substrate. An immense biomass increase in the target species European lobster (2.157.265%) and Brown crab (857.281%) was predicted with the addition of hard substrate. additionally, target species Atlantic cod and cuttlefish showed an increase of 1897% and 175% respectively. Surprisingly, European seabass was predicted to decrease with 93%. The estimated biomass was included in a study in the strengths and weaknesses of the business opportunities based on the Fish-as-a-Service concept. Costs and revenues throughout the lifetime of the sustainable fishery were taken into account, resulting in a final investment advice. The PERTH method was used to account for the uncertainty of estimating the costs of such a project. A detailed cash flow analysis was carried out in order to present a clear view on the different financial scenarios. The cash flow analysis showed a final Net Present Value (NPV) at year 25 of values between 3000 and 6000 mln EUR. This shows the profitability of the proposed design, with an Internal Rate of Return after tax of 69,90%.

Many quay walls in Amsterdam have surpassed their structural lifetime and have started showing signs of damage. The city of Amsterdam is currently tackling the problem and have published a plan of action. This plan includes the renovation of hundreds of kilometres of quay walls. Given this enormous amount, it is necessary to prioritize certain quay walls over others based on the severity of their damage. Some quay walls have reached total collapse, of which the most recent case involves the "Grimburgwal" quay. The municipality has no accurate view of the current condition of quay walls in Amsterdam. On top of that, the vast majority of quay walls have not been assessed on their safety. It is known that the most vulnerable quay walls types consist of masonry walls, supported by wooden foundation structures. Given that the quay wall renovation project requires prioritisation, it is necessary to gain more information on how the most vulnerable walls are recognised. Preferably, a method should be developed in which only visual cues given by the masonry wall are required, as it is quick and relatively cheap. To gain information on what these visual cues might be, a three-dimensional finite element model is made to run simulations on possible behaviours of quay walls. In this thesis, it is attempted to model a quay wall as realistically as possible. Several different deterioration conditions will be applied to see how the masonry responds. The 3D model is built using a parametric model coded in Python. This code can be used to run simulations in the finite element software DIANA FEA. Many behavioural aspects have been incorporated into the model, with the purpose to make the model more realistic. The model consists of a masonry wall, planks on which the wall rests, and supporting piles. The behaviour of each component has been applied in the code and have been obtained through other literature and European norms. The model is loaded by simulating the weight of the soil and its effect on the quay wall structure. The masonry is simulated using a smeared cracking model (macro-model). Long-term deterioration of quay walls is simulated by changing the material properties of each respective component. This thesis focuses on three deterioration conditions: 1. Non-uniform pile degradation: application of broken piles, simulated by removal of those piles from the model. This is subdivided into two categories: removal of entire rows (a row consisting of a front, middle and end pile) and removal of front piles only. 2. Non-uniform soil removal: formation of soil pits at the foundation level, which result in decreased bedding around the foundation piles. 3. Uniform degradation: application of uniform deterioration along a stretch of quay walls. The simulations yield fairly consistent cracking patterns, in which the same crack fields appear in each simulation depending on the chosen case mentioned before. Displacement patterns are also documented and presented in all cases. The quay wall model is able to display in-plane and out-of-plane movement simultaneously. The effect of each parameter on the crack/displacement patterns are analysed as well. This includes masonry and wood quality. The results show that the largest in-plane settlements are reached by damaged piles, while the largest out-of-plane displacements are caused by a loss of soil bedding around the piles. The results can be used to provide better insight on how quay walls with poor quality present themselves in real life and what their cause might be. This research contributes to the possibility of improving recognition of quay walls which find themselves in critical condition, which can then be prioritized for renovations. For future research, it is recommended to see whether time-dependent simulations can be run, to see if it makes a difference in the outcome of displacement/cracking patterns. Another important recommendation is to look into deterioration rates of materials, which could be used as another indicator for critically damaged quay walls.