Sea locks are a barrier between sea water and fresher inland water, allowing for control of inland water levels. They help maintain navigability for vessels, ensuring the connection of hinterland ports to the global shipping network. At the same time, they ensure the continued availability of drinking water, fresh water for agriculture and industry, and contribute to ecological stability by regulating water quality. However, the locking operations needed for vessel passings lead to salt intrusion and thus a reduction in the water quality of the inland waters. With climate change, longer periods of drought and an increase in sea water levels are expected, which increases the salt intrusion. And the growth of the global vessel industry means larger locks are needed to ensure navigability of the increasing vessel sizes, which increases the salt intrusion even more. We observe that measures taken by governments to reduce salt intrusion around locks require insight into both shipping impacts and salt exchange effects. Currently there seem no methods available to quantify how operational measures to reduce salt intrusion around locks impact both the shipping performance and salt levels behind the lock. This thesis investigates how we can overcome this gap in literature.

A first step is to identify how vessels pass shipping locks. We identify the important events that make up the entire lock passage procedure of a ship. Specifically we distinguish: approach, doors open, sailing in, doors closing, levelling, doors opening, sailing out and doors closing again. Next, we identify how the hydrodynamic processes that occur during the locking process influence salt intrusion. The most impactful hydrodynamic processes that occur are taking place between doors opening and closing, and during levelling.

Next we investigate what models are available to simulate both the shipping events and the salt exchange events. While there are several modelling concepts out there, we conclude that for the challenge at hand it is most suitable to use the mesoscopic agent-based traffic simulation model OpenTNSim to simulate vessel passages through locks. We couple this with the semi-empirical salt exchange model called the Zeesluisformulering. The main reason to choose this combination is that a discrete event agent based nautical traffic model captures exactly those events that drive the salt exchange estimates of the Zeesluisformulering. By combining both methods we get a new method that allows us to quantify how salt intrusion mitigation measures affect shipping performance and salt levels intrusion through the lock.

To determine how well the proposed combination of models works in practice we apply it to a real world case. For this thesis we select as our case location the Sea Lock IJmuiden, which at this point is the largest sea lock in the world. The lock complex in IJmuiden is suitable as a case, in February and March of 2023 salt intrusion measurements have been taken by Deltares and Rijkswaterstaat. During this period we also know what ships passed the locks, based on records taken by maritime students of the Amsterdam University of Applied Sciences. Based on these data sources we can test if the combination of models is capable of reproducing the observed behaviour...
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The lock of Hansweert, located in the province of Zeeland in the Netherlands, serves as a crucial inland shipping node between the Western Scheldt estuary and the Rhine Delta. The outer harbour of the lock complex provides the connection to the Western Scheldt and accommodates waiting facilities for inland ships. The Western Scheldt is a vital gateway for maritime traffic, linking the Port of Antwerp to the North Sea. As the navigation channel of the Western Scheldt is located close to the outer harbour of Hansweert, multiple ship incidents at this location are attributed to the water motions generated by passing seagoing vessels on the Western Scheldt. This research investigates how the water motions induced by passing vessels in the Western Scheldt contribute to unsafe situations in the outer harbour and locks of Hansweert, and what preventative measures can be identified to effectively minimize incidents and mitigate risks.

Investigating the incident records reveals that the key contributors are the primary water motions generated by the passing vessels in the Western Scheldt. The phenomenon, experienced as a sudden lowering of the water level and suction forces, can lead to the breakage of mooring lines and uncontrolled movements of inland ships, resulting in a range of safety hazards and operational disruptions. Several documented incidents, field studies and interviews highlight the urgency for effective measures to mitigate the potentially harmful effects of passing vessels on the ships in the Hansweert outer harbour and locks.

A seven-week measurement campaign, involving 1281 passages of so-called oversized vessels, reveals distinct patterns of water level fluctuations during a vessel’s passage. A vessel is considered oversized if its length exceeds 210 metres or if its draught is larger than 10 metres. These patterns are described as a translatory drawdown wave travelling into the harbour, reflecting against the lock complex and oscillating back and forth in the outer harbour until dampened. The key parameter characterizing this wave is the lowering of the water level, referred to as the drawdown height. The average measured drawdown height approximates 6 centimetres, with maximum observations up to 40 centimetres. The main factors influencing the drawdown height are the vessel’s passing distance to the outer harbour, its speed relative to the currents and its dimensions, shown by a correlation analysis between the parameters describing the passing vessel and the generated drawdown height. Extreme drawdown events were exclusively observed during a combination of a relatively high speed through the water of the seagoing vessel and small passing distances relative to the harbour’s entrance.

The impact of the drawdown effects on the inland ships is determined by the forces generated by the pressure difference along the ships, caused by the inclination of the water level. A critical drawdown height of 12 centimetres is set, based on existing force criteria and the linear relation between the drawdown height and water level slope. To improve on the existing drawdown height prediction methods, a site-specific drawdown height prediction equation has been derived. Validation of this equation using the observations made during the measurement campaign yields a Pearson correlation coefficient of 0.81 and an Mean Absolute Error score of 2.2 centimetres.

Preventative measures are identified, aiming to minimize incidents and mitigate the risks related to the water motions induced by passing vessels. The predicted drawdown, generated by the passing vessel, is kept below the critical level by recommending a maximum speed related to the passing distance and dimensions of the vessel. Practically, this measure could be applied as a calculation tool or as an overlay on the pilot’s electronic sea chart. Coupling this information with awareness campaigns for pilots will contribute to minimizing the adverse effects on the ships in the outer harbour. The resilience against drawdown-induced risks could be strengthened by restricting the maximum combined width of ships moored alongside. Furthermore, by limiting the excessive slack in the lines of the moored ships, through signage and floating bollards, the movements of the ships will be restricted, reducing the risk of line breakage. Notifications of anticipated critical drawdowns would allow traffic controllers or lock operators to caution the inland ships and delay the lock chamber door openings, whilst alerting the passing vessel. Incorporating the mitigation measures recommended in this research could positively impact the safety of navigation in the Hansweert outer harbour and locks. ... Read more

In recent years, several logistic optimisation models have emerged as powerful tools to assess and optimise the planning, costs, and workability of marine operations. Nevertheless, these models often rely on two underlying assumptions: (1) the significant wave height and peak wave period adequately describe (directional) wave fields, and (2) these two parameters sufficiently describe the conditions causing weather downtime. However, little is known about how these underlying assumptions affect the reliability of logistic optimisation tools. This study, therefore, presents an alternative model that integrates response motions of vessels and turbine structures into a logistic optimisation tool to address and expose the implications that follow from using these assumptions. A case-study approach, on two recently realised offshore wind farm projects, showed that integrating response motions results in, up to 10%, less favourable workability conditions. Further analysis on the data showed that it is crucial to include the two-dimensional wave energy distribution to expose more complex sea states that induce weather downtime. Moreover, a failure analysis approach found that the conditions inducing downtime events are more accurately described by response motions instead of sea state parameters. Therefore, the findings of this study suggest that integrating response motions into logistic optimisation models improves the reliability of the model estimates. Besides, this study suggest that the industry’s approach potentially overestimates the true workability and, therefore, imposes unnecessary operational risks. Hence, the results of this study demonstrate the importance of integrating hydrodynamic engineering knowledge into the assessment and optimisation of project planning, costs, and workability. ... Read more

Because the demand for green energy increases rapidly, it is expected that solar and wind energy will dominate future power generation. New in this field is the development of offshore floating solar systems, consisting of multiple interconnected platforms that are covered with PV panels. Besides satisfying the demand for electricity, these floating solar systems may have a beneficial impact on their wave environment. If waves are attenuated, down-wave shadow zones could be useful for other marine activities such as aquaculture or for the protection of a harbour, creating opportunities for offshore multi-use. The overall research objective of this study is to research the effect of an interconnected multi-body floating solar structure on the transmission of wave height. This was done using a scale model test and a numerical model, in a two-dimensional setting.

From the scale model tests, wave transmission showed to be highly dependent on the wave frequency, and thus the wavelength, of the incident waves. The floating solar system acts as a low pass filter: it lets the low-frequency waves pass through, whereas the waves with higher frequency are attenuated by the structure. This dependence is governed by the ratio between the incident wavelength and the length of the rigid platforms that the solar structure consists of, measured in parallel to the wave propagation direction. When the wavelengths were smaller than twice the length of a platform, waves were almost fully attenuated. Apart from the dependence on frequency, the basin test results also showed that the amount of wave attenuation increases linearly with the total length of the system, but only with a small slope. Furthermore, analysis of the reflected wave signal indicated that higher-order dissipative effects are likely needed to describe the decrease in transmission accurately, because the amount of wave energy that was reflected by the structure was limited.

A proof-of-concept for applying a linear numerical boundary element diffraction model to a fixed shallow solar structure was carried out. The wave surface elevation could be obtained, and these solutions were in accordance with the physical expectations. The results showed similar trends to the basin test results, but did not match quantitatively. This difference could lie in the model approach, where a two-dimensional transmission coefficient is determined from three-dimensional simulations. It could also be that the scattering effects alone cannot approximate the transmission behaviour of the system, because linear radiation effects or higher-order dissipation effects might be of similar importance and are therefore required for an accurate simulation. Radiation could be included in a linear diffraction model, but dissipation requires higher-order wave theory.

Regarding the multi-use context, a down-wave shadow zone can form if the incident waves are short enough. For the North Sea location considered, waves are typically longer than twice the length of the rigid platforms, thus the floating solar structure might not have the breakwater performance that is desired to protect other offshore activities. ... Read more

During berthing operations vessels use their bow thruster(s) to improve their manoeuvrability, making them less dependent on the assistance of tugboats. The jet from a bow thruster reflects on the quay wall. It is directed towards the bottom where it reflects, causing high flow velocities over the bed. This may scour the nearby bed when it is left unprotected, leading to instability of the quay wall. Over the years, the shipping industry has been developing continuously, characterized primarily by the upscaling in size of inland- and sea-going vessels. As a result, vessels have more power and larger thruster diameters leading to higher hydraulic loads on quay walls and bed protections of berthing facilities. The most common type of bed protection is rip-rap (partially) penetrated with concrete. However, due to the complex flow field of the reflected jet, the decay profile of the near-bed flow velocities is unknown. This results in uncertainties in the design of bed protections and the required width of these protections that must be penetrated with concrete. In this research, the decay of the near-bed flow velocity in perpendicular direction to the quay wall induced by a 4-channel bow thruster is researched. The eventual goal is to provide a better indication to what extent the bed protection must be penetrated with concrete. Field measurements have been conducted in the North Sea Port of Gent with the Somtrans XXV, one of the largest inland vessels in the Netherlands. The flow velocities near the bed, induced by the bow thruster, have been measured with Acoustic Doppler Velocimeters (ADV), Acoustic Doppler Current Profilers (ADCP) and Ott meters (Ott). The results from the flow velocity measurements have been analysed on three main parameters: influence of the applied bow thruster power, the distance between the measurement instrument frame and the bow thruster and quay wall clearance. The highest flow velocities are measured near the quay wall in the order of 1 m/s reaching up to a maximum of 1.8 m/s. Further away from the quay, the flow rapidly declines towards a more constant level of approximately 0.3-0.4 m/s. To define the maximum load on the bed, the mean flow velocity plus three times the standard deviation is used resulting in a maximum load ranging between 1.6-2.8 times the mean horizontal flow velocity. The Dutch and German guidelines for determining the near-bed flow velocities generally overestimate the measurement results. In addition, the dependency of the Dutch method on the total travelled distance by the jet, based on the sum of the quay wall clearance, the height of the bow thruster above the bed and the distance x from the quay wall, are not reflected in the measurement results. It is recommended that this extensive and unique data set acquired through the field measurements in Gent is further used to analyse the flow field of a reflected jet on a vertical quay wall by validating numerical and scale models. Combining these three different methodologies will contribute to a better understanding of this phenomenon with the eventual goal of optimizing the design of bed protections. ... Read more

Moored vessels in harbours around the world are affected by waves penetrating into the port basin. Hydraulic conditions can lead to severe vessel motions that influence the (un)loading efficiency and can even lead to the failure of fenders and mooring lines, creating unsafe situations for operating staff and
A DMA is a chain of numerical models that computes motions of moored vessels due to wind, currents or waves. It is used to model the behaviour of moored ships to evaluate operational conditions and assess the effect of structural or operational measures. The most computational costly model in the DMA chain is the wave penetration model, which computes local wave field, speeding up this part of model chain can reduce time and costs of such DMA's.
In this research, the complex wave model is replaced by a computationally efficient alternative and the main research question reads:
How can a mild-slope wave model be used for the ship motion calculation on ships moored in ports and what are the benefits and limitations?
The research is split up into two parts: 1) Development of the coupling method and evaluating its application based on academic test cases and 2) Applying the coupling to the case study of La Coruña and assessing its suitability.
A practical and efficient method to extract wave components from the wave penetration model is the r-DPRA tool developed by Deltares. The developed method is applied to the case study of the port of La Coruña. Two separate moments in time of the same bulk carrier are modelled: one with moderate offshore wave conditions and one with more severe conditions.
In the measured time series of the surge and sway motions, a clear low frequency can be found. Similarly, in the simulated time series of the surge and sway motions; both in moderate and heavy cases no low frequency wave patterns can be found. A schematic approach is used to include the long waves in the wave model and ship motion model and this approach caused a low frequency wave pattern to arise and leads to more accurate significant motions.
The comparison between the measured motions and modelled motions demonstrated the complexity of modelling real life events. As the surge and sway motions are caused by second order effects that are not included in the applied linear wave model, it is recommended to apply the developed workaround to schematically include this low wave forcing. The result of this research demonstrates the potential for the development method.
Before directly applying the method, it is recommended to test the suitability of the method on a more fundamental case, this reduces uncertainties related to real life measurements and stronger conclusions about the performance of the coupling can be drawn. Moreover, the coupling should be tested for a case where the 2nd order low frequency wave forcing is negligible. As it is confirmed in this research that the developed method is not suitable for modelling non-linear 2nd order low frequency waves.
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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. ... Read more

The port authority of the Port of Talcahuano has the desire to expand the port. The goal of the expansion is to increase the berth space and attract more vessels, thus increasing their throughput. This report is an advise to the port authority on the possibilities of expanding. Four preliminary port designs aremadewith the requirement of the ability to berth two 180mvessels. AMulti-Criteria Analysis has been used to determine the most suitable scenario. The detailed design for this scenario is composed of a quay design, a dredging plan, an earthquake and tsunami impact analysis, market prospect analysis and a financial analysis. A technical design for port expansion, as well as a market strategy has been advised to the port authority. ... Read more