The key parameters governing collision energy calculation are the velocity of the vessel, its mass, and the angle of approach. The conventional method outlined in the Recommendations of the Committee for Waterfront Structures Harbours and Waterways (EAU, 2012), which was specifically developed for berthing ships, relies on an overly simplistic model that fails to capture the dynamics of ship­to­guiding structure collisions. Nevertheless, in the Netherlands, the Guidelines for Civil Engineering Structures (Richtlijnen Ontwerp Kunstwerken, ROK) suggest that the EAU 2012 method be applied unmodified for guiding structures. This report introduces a methodological approach aimed at refining the calculation of collision energy by addressing specific deficiencies in the existing framework, particularly regarding its application to guiding structures.

The kinetic energy approach used in the EAU 2012 method requires, as inputs, the mass of the ship, its velocity vector normal to the structure, a virtual mass coefficient accounting for water mass moving with the ship, and an eccentricity coefficient accounting for energy loss due to rotation when the ship does not approach the structure parallel.

The literature review identifies critical gaps in the EAU 2012 approach to calculating collision energy for guiding structures. An unsuitable application of the eccentricity coefficient and assumptions about the velocity vector direction, which do not align with actual conditions in ship­to­guiding structure colli­ sions, are discovered. Moreover, the review reveals that the framework does not differentiate between berthing and guiding approaches, resulting in a one­size­fits­all approach that fails to account for the unique characteristics and requirements of guiding structures. The framework only partially includes the ship’s angle of approach to the structure in the kinetic energy calculation. Although the recommen­ dation is to calculate the kinetic energy using the normal ship speed to the structure—thus indirectly accounting for the approach angle—when it comes to the eccentricity coefficient, which relies on ap­ proach geometry, the recommendation is to consider the total velocity vector. This practice results in exaggerated collision energy when a ship maintains forward speed near guiding structures while passing through the lock.

The theoretical refinement proposed in this thesis focuses on the scenario where the ship approaches a guiding structure with purely longitudinal speed. Specifically, a new definition for the angle variable in the eccentricity coefficient expression is proposed, which directly reflects the effect of the approach angle of the ship linked to the contributing velocity vector and not only laterally through the magnitude of the contributing vector. This proposed change is validated through comparative analysis.

The comparative analysis is performed using historical data cases from model research published by Ri­ jkswaterstaat (Ministry of Infrastructure and Water Management). The data consist of experiments with ship approaches to structures that have characteristics fitting guiding structure approaches. The ships are of lengths commonly found in lock passages, maintain forward speed, and approach structures similar to those at lock entrances. The historical data provide the maximum force exerted on the tested structure and the resulting deflection. This information is used to derive the energy absorbed by the structure. The published reports valuable to this research resulted in the Virtual Water Mass method. This method is reproduced to provide benchmark values for the kinetic energy absorbed, which are compared to both the EAU 2012 collision energy calculation and the proposed refined calculation for the historical data cases.

The findings of the comparative analysis suggest that the proposed refined calculation provides results closer to the benchmark values than the EAU 2012 calculation. However, a consistent improvement was not discovered. Although the refined calculation is significantly closer to the benchmark value in every case compared to the EAU 2012 calculation, this improvement cannot be quantified as a universal percentage, as it varied for each case. Despite this, the comparative analysis still supports the main objective of demonstrating the exaggeration in the EAU 2012 collision energy calculation.

A case study, as part of this research, explores the potential effect of the refined calculation on an actual structure design. In the case study, the design vessel, velocity, and angle of approach are sourced from the Waterway Guidelines (2011, 2020) and ROK 2.0 (all documents published by Rijkswaterstaat). After calculating the impact energy using the two methods compared in this research, the design of the mono­ pile follows the Blum method. The structure is modeled as a series of piles connected by a main girder, with the girder having the same diameter as the piles to ensure uniformity and strength.

The case of the Volkerak locks is chosen, and calculations using both the standard EAU 2012 method and the proposed refined one are executed. Two designs are produced and compared. With the refined calculation, a design with a smaller pile diameter of 1,620 mm and a longer in­between pile distance of 6.5 m is achieved, compared to the EAU 2012 design, where the pile diameter is 2,020 mm and the distance between piles is 3 m. These results demonstrate the potential for material savings if the refined calculation is adopted.

The study concludes that a refined approach is indeed necessary and that focus should be placed on specific definitions and descriptions in the guidelines. Ambiguity in such definitions leaves decision­ making subject to individual interpretations, creating inconsistency among the designs of structures with the same purpose. Although this inconsistency may not be inherently dangerous, as it usually results in an overly conservative design, it contributes to excess material usage and resource waste.

The expansion of offshore wind farms in the North Sea has raised serious concerns about maritime safety, in particular the increased risk of collisions—or 'allisions'—where a ship adrift hits a stationary structure, such as a wind turbine. For Rijkswaterstaat, the executive agency of the Ministry of Infrastructure and Water Management, managing this expansion requires developing a comprehensive understanding of the integral image of allision risks of drifting ships in the Dutch North Sea region. This understanding must be valid, reliable, and insightful, and include factors such as dynamic weather conditions and shipping activity. Unfortunately, current state-of-the-art methods for estimating the probability of allision rely heavily on assumptions, leading to significant variations in risk estimates, as highlighted by Ellis et al. (2008). These methods usually lack a North Sea-wide perspective and instead focus on risks specific to individual turbines.
This study proposes an approach based on trajectory prediction using the OpenDrift model, which is simple and accessible for simulating ship drift trajectories based on wind, wave, and current data. A method is developed to estimate the probability of allision by combining the probability of a ship drifting into a wind farm, analysed through a ship's potential trajectories, with ship density data for specific locations. This method facilitates the calculation of allision risks under the influence of different environmental conditions and can be applied to multiple wind farms, providing a detailed assessment of the origins of potential threats and available response times.
Overall, the assumptions in state-of-the-art methods might not sufficiently capture the risks associated with drifting ships. In addition, the established method broadens the ability to improve monitoring accuracy and optimise the positioning of ERTVs, even for specific environmental conditions. As a next step, this method should be extended to estimate actual risk levels by considering the potential consequences of an allision. With this approach, decision-making regarding allision threats can be contextualised alongside other maritime safety risks, facilitating the development of a robust risk mitigation strategy that enables Rijkswaterstaat to responsibly exploit the abundant potential the North Sea has to offer.

The surge in demand for inland vessel goods transportation has necessitated the operation of larger vessels with increased drafts. These larger vessels generate significant induced loads from their more powerful bow thrusters during berthing and mooring. These loads can lead to scour, which ultimately results in instability of the quay wall. To counteract this, stone gradings are penetrated with colloidal concrete as bottom protection. However, prior studies indicate that the flow velocity profile perpendicular to a quay wall decreases more rapidly than guidelines suggest, implying a potential reduction in the extent of colloidal concrete application. This is relevant for the Netherlands, where a multitude of hydraulic structures, including an estimated 130 locks, are in need of renovation or replacement. \\

\noindent This study seeks to comprehend the impact of bow thruster-induced loads directly perpendicular to the quay wall, on stone displacement near a quay wall and this study compares the outcomes of this field measurement with existing guidelines and scale modelling. The research question is therefore: ''\textit{How can results from a full-scale test improve the design and performance of loose-rock bottom protection against bow thruster-induced loads for quay walls accommodating inland vessels?}''\\

\noindent In order to answer this question a full-scale field measurement is conducted with the largest inland vessel in Europe. During this field measurement, free flow tests were performed and bottom velocity, pressure fluctuations and stone displacement were determined. \\

\noindent The applied bow thruster power and under keel clearance are marked as two important parameters for stone displacement. For the impact of this applied bow thruster power and under keel clearance, a variety of scenarios is examined. After each scenario a survey is done to look at individual stone displacement. Velocity measurements are taken to get more information about the flow velocities. The velocities were measured relatively far away from the bottom, resulting in low velocities. The actual bottom velocity is determined by validating and using the findings of the scale modelling performed by \textcites{Deltares}.\\

\noindent Free flow tests are performed to directly measure the outflow velocity and compare it with existing guidelines. From these tests, it is concluded that the existing guidelines for outflow velocity result in an overestimation of the required $d_{n50}$, with a measured loss coefficient of 0.65 as opposed to the proposed 0.90. Even with the reduced loss factor for the outflow velocity, the bottom velocity calculated with the Dutch method guideline is higher compared to the actual bottom velocities, demonstrating again, as already indicated in prior studies, that the guidelines are too conservative. \\

\noindent The turbulence intensity values play a significant role in validating the findings derived from scale modelling conducted by Deltares. The measured turbulent intensity values show similarities with the earlier findings, indicating a turbulent environment and validation of the Deltares scale modelling. \\

\noindent Based on pressure measurements, it is estimated that at the onset of movement, the pressure differences of the turbulent eddies are in the order of 50 to 90\% of the critical force to cause stone movement. \\

\noindent The in this study developed parameter R = $\frac{V_0}{UKC} \cdot t \cdot \frac{1}{k_{sl}} \cdot C_R $ shows that an increase in applied bow thruster power, a decrease in under keel clearance, an increase in duration and in slope lead to a linear relation with the normalised cross-section area of the near-quay erosion hole. \\

\noindent In addition, the full-scale field measurement showed that the stone displacement predominantly occurs within the first two and a half meters of the bottom protection, suggesting a possible reduction in the width of the colloidal concrete application. For a fictive quay wall the suggested reduction is compared with the design following the original guidelines. The suggested reduction alternative could save 75\% of the amount of colloidal concrete and CO$_2$ emissions.

Ocean currents play a crucial role in many scientific and industrial applications. Contemporary measurement techniques are limited in spatial coverage or spatial resolution. This study presents a proof-of-concept for a new measurement principle that merges optical satellite imagery of Kelvin wakes with data from the Automatic Identification System (AIS). A case study in the Strait of Gibraltar was performed using two months of Sentinel-2 imagery, which yielded 81 visible Kelvin wakes over 25 images. For each Kelvin wake, currents were estimated in directions parallel and perpendicular to the ship's sailing line. The estimated currents were validated with respect to surface currents derived from High-Frequency Radars (HFRs) and modelled currents from the Copernicus Marine Environmental Monitoring Service (CMEMS). The results suggest that the estimated currents were highly accurate in the absence of large variations in ship course. However, the frequency of measurements is limited by satellite repeat times and Kelvin wake visibility. More research is needed to explore the potential spatiotemporal distribution of measurements.

In the near future, Rijkswaterstaat has the task to replace or renovate many ship locks. With the long-term project, MultiWaterWerk, Rijkswaterstaat aims to standardise components of these ship locks. This thesis contributes to the project by researching the potential benefits of standardisation of the bed protection design at waiting places at ship locks in the Netherlands. Only waiting places for inland vessels with the most commonly used bed materials are analysed. Similar waiting places are grouped together with a classification analysis, based on three parameters: bed material of upper layer, berth type, i.e. quay wall or piles, and expected maximum near-bed flow velocity. The variation in these three parameters and the measured erosion of the bed were then compared between and within the resulting classes. Furthermore, the waiting places are split up into different sizes by pre-defined CEMT-classes. Waiting places in CEMT-class II and VI waterways are more similar in design and erosion, so a potential for standardisation exists there. CEMT-class V is further analysed per corridor, because the variation between all waiting places is too high. Among those corridors, only the Nederrijn-Lek shows potential. In the Meuse and Twente channels, the erosion varies too much; other corridors contain too little waiting places for potential benefits to outweigh the effort for standardisation. It is recommended to standardise the design assumptions concerning ship dimensions and propeller characteristics. A potential standard design vessel per corridor or CEMT-class should lead to a more reliable estimation of the expected scour at the waiting places. Furthermore, estimations for new bed protections at waiting places on lifetime, building duration, cost, and required maintenance will be more reliable because there will be more similar waiting places.

During berthing operations of ships, the horizontal thrusters cause a hydraulic load on the quay wall and bed. This could eventually lead to scour holes in the bed, which may affect the structural integrity of the quay wall. This thesis is about a numerical simulation of a bowthruster jet which is deflected by a quay wall and the focus of this study will be on the resulting bottom velocities. In 2019, field measurements were executed with an inland vessel and the measured bottom velocities were low compared to the design guidelines. The goal of this study is to simulate the field measurements in a numerical model to gather more knowledge about the flow field induced by bowthrusters next to quay walls. The obtained numerical results are compared to the field measurement and to the design guidelines of PIANC. As it turns out, the velocity sensors probably did not measure the maximum bottom velocity during the field measurements, since they are located slightly above the highest velocities at the bottom, as predicted by the numerical simulations. The maximum bottom velocities from the numerical simulation are similar to the expected near-bed bottom velocities by PIANC. However, there is room for improvement in these design guidelines, e.g., adjusting the efflux velocity for tunnel thrusters to account for the variation in cross-sectional area between propeller and tunnel exit.

Salt intrusion poses a threat to the fresh water supply function of inland waterways. How far inland salt intrusion reaches is dependent on a balance of buoyancy forcing, water depth, discharge of the canal and the amount of mixing. Wind, bottom roughness, and sailing ships contribute to mixing. Currently, little is known about the contribution aof the latter to mixing. It is important to better understand the role of ship traffic in order to make more accurate models and take the right measures to protect the fresh water supply function of inland waterways. The flow field in an unstratified canal has been well studied, however, little is known about the effects that ships have in a stratified canal. Ships move water when sailing through a waterway. This induces three water movements: primary and secondary waves and the propeller jet flow. These processes can contribute to mixing by shear instabilities and internal wave breaking.A sailing ship in a stratified canal has been modelled using a moving grid approach in the 3D non-hydrostatic finite element model FinLab to study these effects in detail. The propeller has been neglected to simplify the model. A parameter study has been performed to observe the influence of several parameters (such as the canal blockage, internal Froude number, and canal bank slope) on the flow pattern and the amount of mixing. The amount of mixing is found to be in the order of magnitude of 1 percent for one vessel over 600m canal length a representative range of parameters of canal geometry, density profile, vessel draught and vessel speed. The actual effect will be larger since the internal wave field is still present at the outflow boundary and since the propeller has been omitted from the model set-up. Processes around the vessel and the internal waves contribute about equally to the amount of mixing in the model domain. The internal waves are estimated to have a contribution of about twice as large if the modelled domain was longer. As the interface comes up behind the vessel, it is likely that the propeller jet can have a large impact on the density field directly behind the vessel. The vessel speed, density profile, relative density difference, layer distribution in a two-layer flow, canal blockage, draught to top layer height ratio, and the slope of canal banks are important parameters in the amount of mixing generated. Due to the cumulative effect of the ship traffic, mixing by ship traffic is estimated to be of large importance on the density distribution in a canal. More research is needed to include this effect in large-scale numerical models and find a good parameterisation. How mixing by ship traffic could finally be implemented will be dependent on the numerical model that is used, and the amount of detail that is needed.

Two current assumptions of the Zeesluisformulering (ZSF) regarding a homogeneous lock density and instantaneous shipping are tested against refined descriptions according to literature: a stratified lock density and shipping according the continuity approach. These are implemented into a conceptual model constructed in Python, after which optimizations are quantified by means of a sensitivity analysis and a case study. It was found that by using the new assumption set, a maximum of approximately 10% less salt intrusion is obtained as a result of the influence of the return current on the lock exchange.

In the port of Ostend a discharge sluice is going to be constructed as part of an enforced dike ring. The proposed location of this discharge sluice is close to an already existing marina, the Royal Yachtclub Oostende (RYCO), and hindrance is expected regarding the outflow of the sluice in marina direction. When designing the sluice, an optimal balance has to be found between acceptable flow velocities in the downstream area and the capacity of the discharge sluice. It is therefore very important to be able to determine resulting flow patterns.

Formulas and rules of thumb found in literature are not sufficient to determine the resulting flow pattern of this system due to the complex geometry, including a pile row for flow velocity reduction. Other studies have shown that numerical models could simulate flow patterns of discharge sluices with much detail. However, a lot of detail in the results also requires much computational time. An example of a detailed numerical software program that is able to simulate the complete three-dimensional flow field is COMSOL Multiphysics 5.6 (COMSOL). Although it provides the most detail, simulating the flow in the entire area of interest (including the RYCO) for a complete tidal cycle in COMSOL would take too much computational time.

The objective of the present study is therefore to investigate the possibilities of determining the flow pattern downstream of a discharge sluice using a numerical method that requires less computational time but has sufficient accuracy to determine the potential impact of a discharge sluice on nautical activities.

In the present study, two options are considered to determine the flow field downstream of a discharge sluice. Method COMSOL-D3D is a coupled numerical method of a COMSOL and a coarser Delft3D-FLOW 4 (D3D) model. The other option, method D3D, uses only a D3D model and the sluice outflow is schematized by means of the general discharge relation.

As validation of the results is not possible due to a lack of measurement data, the methods are applied to a simplified case. The flow pattern resulting from each method is compared to the results obtained with a so-called baseline method. This method consists of modelling the entire domain with only a detailed numerical model, COMSOL. This is possible since, for validation purpose, the domain of the simplified case is relatively small and only stationary conditions are considered.

In conclusion, there is a lot of potential in the use of both methods in predicting the flow pattern downstream of a discharge sluice. They produce for the simplified case flow patterns similar to those obtained with the detailed method. Moreover, both methods require relatively little computational time compared to a full 3D simulation, method D3D requires the least amount. However, there are a number of conditions for the application of both methods.

The methods cannot be applied in the direct vicinity of the discharge sluice where the flow is highly three-dimensional. If one is interested in the flow in the first meters after the outflow opening or around the pile row, for example for designing the bottom protection, the two considered options are not sufficiently accurate. The flow in this area is too complex to simulate in a D3D model. In this case it is recommended to model the situation completely in COMSOL or a model similar to COMSOL. Furthermore, method D3D can only be applied if the sluice system is simple enough to correctly determine the discharge coefficient analytically/empirically and to simulate the effect of the pile row with a simplification in D3D. It is possible to accurately determine the effect of the pile row on the flow in this study with a schematized porous plate in D3D. Further research must show whether this applies to all types of pile rows.

For method COMSOL-D3D it is important that a correct coupling is made between both models. Here it is important to gradually impose the flow rates in the D3D model. Furthermore, the coupling should be made before the predicted point at which the jets starts deflecting towards the side but downstream of the area at which three-dimensional flows caused by the pile row are present.

It is important to note that due to a lack of validation data there is an uncertainty in the results following from the model approaches. Further research and the use of validation data must show how accurate the results of the considered methods are.

In this research method D3D is applied to the Ostend case. It becomes clear that flow rates exceed predetermined limits for safe operation in the marina. This applies to the entire marina and a large part of the time that the discharge sluice is discharging in marina direction. Measures will therefore have to be taken to prevent this. It is recommended to use method COMSOL-D3D to investigate the optimization between flow velocities in the marina and the discharge capacity. This is due to the fact that the design of the discharge sluice is expected to become much more complex and as a result the discharge coefficient is no longer easy to determine using formulas from literature.

Ships in rivers create waves and these can have a negative impact on fish habitats along the river banks. A modelling study is carried out to investigate how these ship-induced waves can be damped in groyne fields by making structural modifications to the groynes. For this purpose, different types of openings (notches) are applied to the groynes. Next, hydro-ecologic indicators are used to assess the impact of notching of groynes on fish habitat suitability. The results suggest that relatively simple modifications can significantly improve the ecological value of the groyne fields.

A main challenge port engineers had to tackle in recent years is wave penetration inside a harbour, as it determines vessels’ safe sailing and mooring, possibly causes unwanted vessel movements, and unequivocally regulates the execution of port operations. A physical scale model can describe wave penetration in a complete way. However, the construction of a physical scale model is expensive and time consuming. For this reason, nowadays several numerical models are used to describe wave penetration in ports, affected by multiple processes such as diffraction, partial reflection, etc. In this study, the simulation of wave penetration with the non-hydrostatic model SWASH is examined. To validate the numerical model, output of an open benchmark dataset of Deltares (Deltares, 2016) is used, consisting of physical scale model tests of schematic port layouts. As wave penetration is a summation of physical processes, each process should be described accurately by SWASH. This thesis focuses on assessing how SWASH models wave penetration per wave process, first separately by means of simplified models and then combined in a model describing the full harbour layout resulting to the final wave field inside a port. The main topics of interest of the formulated research questions are the ability of SWASH to simulate wave propagation, wave celerity and the effect of two dominant wave processes: reflection and diffraction. As the amount of processes influencing wave penetration increases for higher layout complexity, the research was targeted at the simplest port layout considered in the benchmark dataset (Deltares, 2016). Moreover, only regular waves were taken into account, as in this case the differences between the measurements and the computational results are most easily identified. To better understand the influence of reflection the waves, two simplified one-dimensional SWASH models were designed. The first model simulated reflection in front of a gravel slope, located outside the harbour basin, and the second model reflection in front of the harbour basin end, consisting of a gravel slope and a concrete quay wall behind it. The results suggest that outside the basin the reflection off the gravel slope has a minor effect in comparison to the reflection off a vertical quay wall. Inside the harbour basin, wave reflection played a dominant role on the resulting wave field there. The SWASH models were proven to be robust as the wave height in the computational domain did not change considerably for an increase or decrease of the porosity of a gravel slope by 10%. It should be emphasised that the standing wave heights were altering fast within a short horizontal distance. Therefore, the precise wave height values were strongly influenced by the exact location of the output points examined. The importance of diffraction inside the harbour was demonstrated by a simplified two-dimensional model, in which reflection off the harbour end was not included. The information that could be obtained from the measurements about the wave height changes due to diffraction was limited. However, the initial trends due to diffraction were also identified in SWASH. From the comparison of the wave height in the SWASH model, influenced only by diffraction, to the respective measured value, it was confirmed that the total measured wave penetration inside the harbour was significantly influenced by diffraction. The comparison of the measurements to the results of the final SWASH model, which included the full version of the simplest physical model, showed that the overall wave field pattern is in agreement. The numerical model was able to reproduce the diffraction and reflection patterns observed in the measurements. At many output locations in SWASH the measured wave height values were simulated with high accuracy. On the downside, at other locations the measured and the modelled wave height deviated significantly. The large deviations can be explained by the fact that the standing wave patterns change within a short distance and thus the wave height can vary significantly at the area close to a specific output point. It may be possible that the measured wave height at a specific point can be identified in SWASH in the region close to the exact point coordinates. All in all, it was concluded that for non-breaking, relatively low waves, with wave height to water-depth ratio lower than 0.2, the accuracy of SWASH in modelling the wave processes of reflection and diffraction is sufficiently well for engineering purposes. For relatively high waves and/or breaking waves, numerical instabilities were detected. It is assumed that the numerical instabilities can be attributed to the relatively low number of grid cells per wave length. This study advances our understanding of the wave penetration simulation in SWASH. The approach followed allows investigating the ability of the model to simulate, separately and combined, two wave processes which predominantly contribute to wave penetration in harbour: reflection and diffraction. With further validation to guarantee the model stability, the strategy of this thesis can be a useful tool to understand the performance of SWASH in modeling wave penetration per wave process and in combination. The knowledge obtained enlightens the possible reasons leading to deviations between the measurements and the model outputs. This can be valuable assistance in the course of further improving the model accuracy.