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.

Sint Eustatius is a Caribbean island located in the north of the Lesser Antilles. The coastline west of the capital, Oranjestad Bay, is of vital importance to the island as it is here where tourism, recreation, the harbour and historical ruins are located. On the other hand, Oranjestad Bay has a heavily fluctuating beach, which is undesirable. The Public Entity of St. Eustatius is investigating the possibility of a coastal solution that could preserve and extend this beach. However, there is insufficient knowledge of the hydrodynamic processes and morphology available to design a solution. By analysing the morphological system, this study aims to advise the Public Entity of St. Eustatius on the decision for a coastal solution to create a beach in Oranjestad Bay.

A literature study was performed to obtain basic knowledge of the coastal system of Oranjestad Bay. A two-dimensional numerical Delft3D model was then developed to gain more in-depth knowledge of the wave, current and sediment patterns. The result of both findings is combined in a conceptual model, where the cause of the beach fluctuations along Oranjestad Bay was analysed. Based on the system knowledge and stakeholders’ demands and regulations, three alternatives to create a beach at Oranjestad Bay are proposed. The alternatives are qualitatively verified and evaluated with a multi-criteria analysis and cost-value ratio.

The literature review shows that Oranjestad Bay has the characteristics of a wave-dominated coast. The seasonal wave climate has a strong influence on the beach fluctuations that occur in Oranjestad Bay. The influence of tides and wind on sediment dynamics is expected to be minimal. The modelling study concluded that the wave climate can be described by three main wave conditions, namely a sea condition, a storm condition and a swell condition. The different hydrodynamic and morphodynamic characteristics of these conditions provide a reasonable simulation of the coastal processes in Oranjestad Bay. The model results give an impression of the seasonal wave climate and a net northward sediment transport capacity is found. These results are consistent with the expected coastal morphodynamics found in the literature study. The effect of a storm is less well represented in the modelling study. This limitation is caused by the modelling approach. In addition, there are some uncertainties in the model due to the lack of detailed coastal data in the nearshore. The conceptual model indicates that the coast of Oranjestad Bay may experience seasonal gradients
in alongshore sediment transport leading to beach fluctuations. From April to September, beaches are likely to erode due to net northward sediment transport. In addition, beaches erode due to periodic storm conditions that occur from June to November. It has been found that the recovery of beaches after a storm varies along Oranjestad Bay. Scubaqua beach recovers much faster than the beach at Smoke Alley. This is due to the larger sediment transport capacity in the alongshore direction at Smoke Alley beach, the amount of larger cobbles on the shoreline of Smoke Alley and the lack of sediment north of Smoke Alley...

During mooring operations, ships tend to make an extensive use of bowthruster in order to minimize the need for tug assistance. Jet caused by transverse thrusters directly impinges quay walls, and can cause scour on the bed, therefore threatening structural stability of quay walls. Presence of vertical quay walls induces reflection of bowthruster's jet, further complicating the already complex flow field. Despite extensive research has been conduced on free flow, several knowledge gaps are still present regarding propeller induced flow when confined, for instance by a vertical quay wall. In this research, focus is on flow field on the bottom of a vertical quay wall induced by channel-type bowthrusters, which are commonly used for inland vessels. Field measurements have been conducted at the Antarcticakade, Ports of Rotterdam, using inland vessel MTS Vorstenbosch. The vessel is equipped with a 4-channel Veth Jet type bowthruster system. Use of a combination of Acoustic Doppler Velocimeters and Acoustic Doppler Current Profilers allowed measurements of flow velocities on the bottom of the quay. Data from the measurements has been analysed to investigate influence of distance between outlet and quay wall, and keel clearance, on the flow pattern at the bottom. Results have then been contextualized within the literature framework, and their impact on design of bottom protection according to most used guidelines has been assessed.
The results of this field measurement showed mean flow velocities near the quay wall generally in the order of magnitude of 1 m/s, with the exception of one test, where mean flow velocities in the order of magnitude of 2 m/s were recorded. This relatively low mean flow velocities were often correlated with large turbulent fluctuations, leading to values of relative turbulence intensities higher than the ones found in literature, and sometimes even equal to 1. Comparison with the theoretical calculations of velocities according to Dutch and German methods suggested by PIANC, showed both methods to be conservative if compared with data from most tests. Furthermore, it appeared that both formulae’s sensitivity to wall and keel clearance was not reflected by the data. Similarly, results from this measurement showed that the flow generated by simultaneous use of two bowthrusters was characterized by velocities on the bed lower than expected according to the guidelines. Recommendation would be to use either linear superposition or to multiply by square root of n (where n is the number of used propellers) when considering the use of multiple propellers, but this was not reflected by most of the data. However, two of the tests taken into exam represented an exception to these general observations: ADV1, the instrument nearer to the quay wall, recorded velocities higher than the theoretical values for tests 12 (use of bowthruster 2 at high water) and 22 (use of both bowthrusters simultaneously at low water). Results from this study showed how the use of a 4-channel bowthruster system induced a flow on the bottom of a vertical quay wall which is mainly divided in two zones. Near the quay wall is where the highest velocities have been measured, and where the flow is strictly influenced by use of the bowthrusters. There is a return flow beneath the ship, which is dissipated in the space of few meters. Underneath the suction points of the bowthrusters, it is the inflow to determine the flow characteristics on the bed. In this research, the extent of the bowthruster-induced flow was found to be less than 14 m from the quay wall. The instrument hereby located, in fact, didn't record velocities which were affected by the use of bowthrusters. This research represents a step towards filling the knowledge gaps about use of bowthrusters at a vertical quay wall. The unique dataset collected can be used in the future for validating numerical or on-scale models, working for a better understanding of the phenomenon and a more accurate and optimized design of bed protections.