Abstract: Efficient port operations require minimizing turnaround time which is the total duration of a vessel's stay in the port and encompasses waiting, maneuvering, berthing, and de-berthing times. The turnaround time can be reduced by optimizing arrivals and departures, maximizing berth availability, facilitating cargo handling, and maintaining water depth. Maintenance dredging, the primary method for maintaining water depth, is used as a continuous activity to ensure the available water depth is sufficient for the navigation of commercial (seagoing, inland, barges, etc.) vessels. The continuity of maintenance dredging interferes with commercial vessels that aim to be served in terminals. Despite the cost imposed on port authorities due to these interferences, addressing this challenge in a structured way is overlooked. To fill this gap, an open-source discrete-event model is presented in this study that employs agent-based simulation to model the interaction between seagoing and maintenance dredging processes. A simple case is proposed to provide an example of how this interaction is simulated. Then, the implications and limitations of this study are discussed and the directions for future research are recommended.@en

This paper tackles the growing challenges in urban logistics by presenting an optimal distribution network that integrates urban waterways and last-mile delivery, tailored for cities boasting extensive waterway networks. We examine Amsterdam's city center as a case study, prompted by the strain on quay walls, congestion, and emissions, urging a reevaluation of its urban logistics design. We formulate the problem as a two-echelon location routing problem with time windows and introduce a hybrid solution approach for effective resolution. Our algorithm consistently outperforms existing methods, with a superior solution quality, demonstrating its effectiveness across established and newly developed benchmark instances. In our case study, we evaluate the benefits of transitioning from a roadway-centric to a waterway-based system, showcasing significant cost savings (approximately 28 %), reductions in vehicle weight (approximately 43 %), and minimized travel distances (approximately 80 %) within the city center. The integration of electric vehicles enhances environmental sustainability, resulting in a total daily emission reduction of 43.46 kg. Our study underscores the untapped potential of inland waterways in easing urban logistics challenges. Inspired by Amsterdam's experience, global cities can adopt innovative approaches for sustainable logistics, providing valuable insights for managers striving to enhance efficiency, cut costs, and promote sustainable transportation practices.

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Ports and waterways are key in supporting the waterborne supply chains that form the backbone of global trade. Maintaining adequate water depth is vital for accessibility and safe navigation. Port authorities and contractors are the key players in developing maintenance strategies, and they strive for a mutually beneficial compromise. Port authorities aim to optimize port performance while keeping costs and delays at acceptable levels. Contractors aim to optimize the use of equipment and execution strategies to achieve cost-effectiveness and time efficiency. While minimum cost and duration are common and simple decision criteria, there is growing societal pressure to incorporate smart, sustainable, and circular elements. However, these elements are less straightforward to interpret and there is a lack of a comprehensive framework to quantify smart, circular, and sustainable strategies. This lack of clarity presents significant challenges in balancing traditional and emerging objectives in port maintenance. Our study directly addresses this gap by providing a structured approach to decision-making that integrates these critical but complex elements. As a result, trade-offs on these important issues are harder to achieve reducing the contributions of port authorities and contractors. This study addresses this gap by applying the Frame of Reference (FoR) method to extract objectives and indicators for decision-making from both the port authorities' and contractors' perspectives. We fill in the prescribed elements of the basic FoR template through a systematic literature review (SLR), clarifying to what extent consensus exists on these topics. The SLR revealed 128 articles and identified common strategies, research methods, influential journals, and contributing countries. Projecting these findings onto the basic FoR template showed that the protection of marine ecosystems and sediment management has received considerable attention from researchers while mitigating emissions and adopting smart techniques are emerging subjects in the literature that need further investigations. As a result, this study offers theoretical and managerial insights to improve what can be achieved with smart, circular, and sustainable maintenance strategies, while identifying crucial remaining knowledge gaps.@en

Reducing waiting times is crucial for ports to be efficient and competitive. Important causes of waiting times are cascading interactions between realistic hydrodynamics, accessibility policies, vessel-priority rules, and detailed berth availability. The main challenges are determining the cause of waiting and finding rational solutions to reduce waiting time. In this study, we focus on the role of the design depth of a channel on the waiting times. We quantify the performance of channel depth for a representative fleet rather than the common approach of a single normative design vessel. The study relies on a mesoscale agent-based discrete-event model that can take processed Automatic Identification System and hydrodynamic data as its main input. The presented method’s validity is assessed by hindcasting one year of observed anchorage area laytimes for a liquid bulk terminal in the Port of Rotterdam. The hindcast demonstrates that the method predicts the causes of 73.4% of the non-excessive laytimes of vessels, thereby correctly modelling 60.7% of the vessels-of-call. Following a recent deepening of the access channel, cascading waiting times due to tidal restrictions were found to be limited. Nonetheless, the importance of our approach is demonstrated by testing alternative maintained bed level designs, revealing the method’s potential to support rational decision-making in coastal zones.@en

The marine environment faces continuous anthropogenic pressures, including infrastructural developments at a global scale. Integration of nature-inclusive measures in the design of infrastructural development is increasingly encouraged, but a lack of coordination results in fragmentation of project-based measures, failing to meet the desired overall effects. To realize impact at system-scale, i.e. the seascape dimension required to achieve the set objective for a selected ecosystem component, overarching policies with shared targets towards effective nature-inclusive marine infrastructure are needed. We present a stepwise approach to work towards operational objectives for promoting selected ecosystem components that can be species, habitats or ecosystem processes, in which ruling policies, environmental conditions and the use of infrastructural development are aligned, and agreement on achievable ambitions is reached. Having clear targets will provide guidance to project developers in designing the infrastructure nature-inclusive, and in setting up relevant monitoring programs to evaluate the measures taken. We demonstrate how this stepwise approach could be applied to derive operational objectives for the design of nature-inclusive marine infrastructure in the context of offshore windfarm development in the North Sea, currently one of the most prominent infrastructure developments that changes the marine environment drastically. The European flat oyster Ostrea edulis has been selected as target species in the case study, as its once abundant population is now nearly extinct from the North Sea due to human disturbances, and there’s growing interest to restore its reefs. The application of the stepwise approach indicates the potential for oyster reef restoration in the area, based upon a clear match between ruling policy, environmental conditions, and habitat suitability within offshore wind farms. An agreement between the main stakeholders on achievable ambitions can likely be established and would translate into the operational objective to actively introduce oysters to reach an initial critical mass and optimize settlement habitat in all future offshore wind farms in an area with suitable habitat characteristics. Such an agreement on overarching objectives is crucial to align separate initiatives to promote targeted ecosystem components and to jointly become most effective, which is ultimately in the best interest of the larger community using the system.@en

Climate change puts stress on the efficient operation of lock complexes. During more frequent and more severe periods of drought, freshwater losses and saltwater intrusion fluxes through lock operations have to be kept to a minimum to guarantee sufficient freshwater availability. Reduction of the number of lock operations is a measure that is frequently applied. Such measures, while effective to limit saltwater intrusion, generally lead to delays and economic losses for the transport sector. Tools that simultaneously simulate lock operations and saltwater intrusion, appear not to be available in open literature. To contribute, this paper presents a method that is able to perform such analyses, combining a meso-scale logistical model with a semi-empirical hydrodynamic model of a lock. We demonstrate the applicability of the model through a theoretical experiment on the effectiveness of vessel clustering to reduce the number of lockages. Clustering indeed helps to limit saltwater intrusion, at the expense of a significant increase in vessel delay times. Although the model can still be refined, it already enables us to quantify the relationship between vessels’ delay times and local saltwater intrusion fluxes. As such the presented method is an important step forward in the optimization of lock operation in periods of drought.@en

The planning and construction of offshore wind parks reduces the margin for error of nearby shipping activities. During the last couple of years, several incidents on the North Sea have raised the attention for the risk of ship-ship and ship-infrastructure collisions. Although often not the primary cause, environmental conditions play an important role in these incidents, and prevention and intervention measures, like the placement of emergency response vessels, are often deployed considering metocean conditions. To improve the design of risk-reducing measures, we need to understand better how vessels behave under varying environmental conditions. It is important to gain insight into risk patterns at system scale while retaining the ability to explain how these patterns are linked to underlying mechanisms. For this purpose we propose creating a so-called ‘event’ table, that couples ship behaviour data from Automatic Identification System (AIS) data to environmental data. The structure of the ‘event’ table, whereby events are defined as vessels sailing within a specific section of the system, allows appending analysis results and other data sources to the events. We show how the ‘event’ table adds important new perspectives to the analysis of nautical safety at sea.@en

PIANC Task Group 234 concludes that the “path to decarbonization of inland waterway transport is different for different corridors and in different countries”. This calls for an approach that can consider largescale differences as well as local influences when evaluating the emissions of inland vessels. This paper demonstrates the use of a so-called “event table” that allows corridor scale estimations of inland shipping emissions, while retaining the ability to identify the most important source mechanisms that produce these emissions. We considered three corridors in the Netherlands: Antwerp-Rotterdam, Antwerp-Duisburg and Rotterdam-Duisburg. Using the event table and four “pivoting perspectives”, we quantify large-scale emission patterns and investigate underlying mechanisms for these three corridors. Our study shows that despite their close vicinity, different mechanisms are responsible for observed emission peaks on these corridors. On the Antwerp-Rotterdam corridor, the most important contributions to emissions are slowly sailing vessels near the two locks that are on this route. It is furthermore shown that deeper fairway sections contribute to significantly lower emissions locally. On the Rotterdam-Duisburg corridor, we show that river currents significantly influence the emissions of vessels per travelled distance unit. The Antwerp-Duisburg corridor contains a combination of these factors.
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Introduction:
Global coastal flooding maps are now achieving a level of detail suitable for local applications. The resolution of these maps, derived from widely available open data sources, is approaching that of local flooding maps (0.5–100 m), increasing the need for a standardized approach to evaluate underlying assumptions and indicators for local applications.

Methods:
This study introduces the Waterlevel, Elevation, Protection, Flood, Impact, Future (WEPFIF) notation, a structured notation for documenting and comparing key methodological choices and data variations across global coastal flooding studies. This approach enhances the understanding and explanation of the fitness-for- purpose of flood maps. This notation builds on commonly used methodological choices, dataset variations, and model approaches in global flooding risk research. Analysis of these workflows identifies common elements and highlights the need for a more structured reporting approach to improve comparability.

Results:
Applying the WEPFIF notation to a case study in the Netherlands reveals significant variations in flood risk assessments originating from differences in Digital Elevation Model (DEM) and water level selection, and inclusion of protective infrastructure.

Discussion:
WEPFIF, by annotating these methodological variations, enables more informed comparisons between local and global flood studies. This allows researchers and practitioners to select appropriate data and models, based on their specific research objectives. The study proposes tailored approaches for three common types of flood studies: raising concern, optimizing flood protection investments, and representing the state of coastal risk.@en

The rapid degradation of ecosystems jeopardizes the services they provide. Among the most valuable of these services is protection of coastlines by shoreline ecological communities, such as coral reefs, mangroves and salt marshes. Currently, coastal protection potential of ecosystems is estimated primarily as a function of their spatial extent and type. The degree to which coastal protection depends on aspects of biodiversity within and across these ecosystems is, however, much less explored. Here we synthesize evidence from multiple sources to evaluate whether aspects of biodiversity may influence the degree of coastal protection afforded by coastal ecosystems. We discuss relevant biodiversity theory and the few studies that have investigated how species identity affects shoreline protection, as a first attempt to identify the aspects of biodiversity that are likely to be important in enhancing coastal protection efforts. This synthesis should empower ecologists, conservation scientists and practitioners to test for and then harness the unrealized, but high yield potential, of incorporating biodiversity into coastal defense planning.

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The native European flat oyster (Ostrea edulis) is an ecosystem engineer providing important ecosystem services, but became nearly extinct from the North Sea due to diseases and overfishing. There's a growing interest to restore these oyster reefs for their valuable contribution in re-establishing a rich ecosystem in the North Sea. In order to reintroduce the flat oyster population, the availability of hard substrate is crucial for initial settlement and reef development. Such substrate is offered by the infrastructure in offshore wind farms, by means of quarried rock placed at the base of the wind turbine foundations and on top of cable crossings to prevent scouring of the seabed. Further anthropogenic disturbances of the seabed are largely restricted, making wind farm areas promising sites for oyster reef restoration. For successful oyster reef initiation, offering a suitable type of substrate for larvae settlement is important. Here, we assess the settlement preference of flat oysters on 9 different types of substrate, by comparing total settlement, spat densities and spat survival. Oyster larvae settlement preference based on the total number of spat per surface area of the substrate was the highest for granite, a rock type conventionally used as scour protection in offshore wind farms. The lowest settlement preference was observed for steel and the biodegradable polymer BESE. The experiments were performed in a spatting pond and in a natural bay to be able to compare spat collection under controlled and natural conditions. Settlement rates in the spatting pond were much higher than in the natural environment, though survival rates were lower. Our results provide insight in the settlement preference of the European flat oyster for different types of substrate under controlled and natural conditions. Knowing these favorable substrates and conditions for oyster larvae settlement allows for the selection of pro-active measures that contribute to flat oyster reef restoration in the North Sea.

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The weirs in the Meuse river in the Netherlands are after 100 years end of technical lifetime. As a consequence, Rijkswaterstaat is planning renovation or complete replacement. The present weir openings of 60 m wide are used for transit of vessels at high river discharges, when the weirs are lowered. Based on agreements between Belgium and the Netherlands from 1839 [1] and 1843 [2], the possibility of sailing through the weirs during high river discharges should remain (principle of non-deterioration). For the case of replacement, Rijkswaterstaat had a preference for a weir with three openings, for reasons of maintenance and water management. The Dutch MARIN institute executed fast time- and real time simulations to get insight in the navigability of a weir, with openings of 38, 38 and 24 m wide. Results were also used for improvement of the Dutch Guidelines for waterways 2020 [3]. The weir at Sambeek was taken as representative for the other Dutch weirs in the Meuse; 3D flow charts were delivered by the Dutch Deltares institute. The MARIN research showed, that the configuration studied was not feasible; recommended was a middle weir opening of at least around 50 m wide, corresponding with the swept path approaching the weir of 36 m plus ½B at both sides.@en

Purpose: Maintenance dredging can often hinder port operations resulting in waiting times for seagoing vessels. The purpose of this paper is to investigate the dynamics between maintenance dredging activities and seagoing vessels, specifically focusing on how waiting times can be reduced. Then, the role of selecting different maintenance dredging strategies in reducing these waiting times is outlined. Methods: The study analyzes historical automatic identification system (AIS) data to identify the interaction between maintenance dredging and seagoing vessels and quantify the hindrance periods for the Mississippihaven case study in the Port of Rotterdam, the Netherlands. The trajectories of the vessels are analyzed in a simple case to show how the vessels interact and how the waiting times are quantified. The interactions are checked with the Port of Rotterdam for different port calls to ensure that maintenance dredging was the reason for these delays. Results: By analyzing the AIS data analysis of vessels in a given time window, the dredgers for maintenance work can be identified and their activities within or near the terminal can be determined. In addition, the waiting time of the seagoing vessel caused by the maintenance dredging is quantified at the terminal entrance. Conclusion: The study discusses how the maintenance dredging operations could be improved by adjusting the loading and sailing phases of maintenance dredging and provides some theoretical and managerial insights. Alternative port maintenance strategies to minimize the waiting time caused by the hindrance are also discussed.

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Cross-habitat facilitative processes can enhance seascape restoration outcomes but there is uncertainty around the spatial dependencies of these processes across habitats. We synthesised the influence of environmental parameters on six processes underpinning cross-habitat facilitation and identified the linear distances over which they operate between habitats. All six process types occur at distances commonly used in seascape restoration demonstrating how harnessing facilitation can scale-up restoration to meet national and international goals.

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Marine reef ecosystems have degraded massively worldwide, and restoration efforts have as yet not managed to realize the scale required to reverse continued degradation. To achieve effective scales, scientific insights in restoration methods should be paired with industry-based approaches used for infrastructural development. We illustrate by five principles how long-standing experience of marine contractors with executing large-scale projects, can support reef restoration: i) utilizing industrial techniques to achieve positive impact at scale, ii) landscaping infrastructure to optimize habitat for targeted species, iii) inducing life to overcome connectivity bottle-necks and steer community composition, iv) designing nature development efforts to be self-sustainable, and v) ensuring continuity beyond project boundaries by early stakeholder engagement. Consciously connecting scientific knowledge to industry-based activities increases the likelihood that marine infrastructure development and ecosystem rehabilitation can be aligned. We plead that synergizing practices by science and industry is needed to upscale restoration efforts and truly improve marine reef ecosystems.@en

Inland shipping is a key modality for freight transport between the seaport of Rotterdam and the industrial areas in Germany and Switzerland. The recent droughts of 2018, 2019 and 2022 have clearly demonstrated how discharge related supply chain disruptions cause substantial economic damages in the hinterland. The IPCC predicts that climate change will increase the variability in water cycles globally, making future extremes more frequent and more severe. In-depth insight into the response of inland shipping to discharge extremes is crucial to better anticipate and potentially mitigate this climate risk. Existing literature takes (a small number of) representative vessels and estimates corridor scale climate risks through extrapolation. Recent droughts have shown that this approach may give unrealistic results. Newspaper articles and reports from the sector suggest that the fleet composition and vessel deployment change during high and low discharge extremes, and cascading effects are likely to occur. So far, however, no objective data on this phenomenon has been reported in literature. This paper analyses ten years of IVS and discharge data, for the period between 2010 and 2020, revealing in detail for the first time how discharge levels and vessel deployment are related. This improved insight into shipping response is crucial for any corridor to accurately estimate the climate risk of discharge extremes. While this paper focuses on the Rhine corridor, the proposed method is applicable to other corridors as well.@en

Incorporation of ecology and ecosystem services into marine infrastructural developments has gained interest over the last decades. Growing attention is given to combine the massive roll-out of offshore wind farms in the North Sea with reinstating the once rich but nowadays nearly extinct European flat oyster (Ostrea edulis). However, the practical upscaling of these pilots is hindered by the absence of clear management objectives and the lack of quantitative knowledge on the effect of technical interventions that could stimulate oyster reef development. Consequently, it is unclear what scale of intervention would actually be required to achieve overall management objectives. This paper presents a stepwise procedure designed in particular to guide the selection of appropriate measures and their required scale for pro-actively facilitating flat oyster reef development in offshore wind farms, in order to reach a desired state for oyster reef inclusive wind farms. The stepwise procedure addresses the historical and current situation of the physical system and social environment, provides options for intervention that stimulate oyster reef development at a range of scales, from micro-scale (materials used) to mega-scale (connectivity between wind farms), and quantitatively assesses the potential effect of applying these interventions. Assumptions have been made in quantifying the effort required for developing oyster reefs in offshore wind farms, and refinement is obviously needed. However, this is a first attempt to make such estimates. The outcomes provide direction in identifying research needs to fill knowledge gaps, as well as in decision-making during the design process for inducing oyster reef development in offshore wind farms. Herewith, application of the stepwise procedure supports authorities in restoration management for the successful reinstatement of flat oyster reefs in the southern North Sea.

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Several measures have been developed to prevent emissions from inland water transportation. However, it is challenging to weigh all the aspects to identify the pathway that will ultimately result in zero-emission inland shipping. A data-driven virtual representation of the inland shipping system can be used to evaluate zero-emission strategies, effectiveness of policies and technologies, and consequences of their implementation. This multi-level digital twin can realistically represent the system with all relevant components, which needs to be validated using real-world data. Subsequently, future scenarios can be imposed on the digital twin, and the proposed intervention measures can be applied, based on which their efficiency can be assessed together with the inland shipping sector. This study discusses the essential aspects of designing a digital twin for an IWT. Three aspects are considered essential: individual ships, logistics chains, and infrastructure. As these research topics span various scales, ranging from a single vessel to an entire infrastructure network, an agent-based approach is suitable for forming the basis of the digital twin. Consequently, potential interventions can be considered, ranging from the application of new technologies to individual vessels to policy measures implemented for an entire shipping corridor or various bunker infrastructure strategies in the network. Additionally, the impact of the implemented interventions can be evaluated at any desired scale, ranging from the individual ship level and its emissions to the network level and aggregated emissions in an entire area, or the impact on the logistics chain.@en