Maintenance dredging in ports and waterways is essential to ensure safe navigation. With increasing regulatory pressure on the maritime sector to reduce exhaust emissions, both dredging contractors and port authorities are seeking effective mitigation strategies. However, accurate emission estimates for maintenance dredging activities are still limited in the literature and often rely on experiential knowledge rather than scientific methodologies. This study suggests a method for estimating emissions and comparing alternative maintenance dredging strategies by quantifying trade-offs between project duration, energy consumption, and emissions. The method integrates vessel characteristics, project specifications, and sediment properties to allow for situation-specific, realistic assessments. A discrete-event simulation is used to evaluate two alternative scenarios, offering insights into the impact of key parameters on vessel selection and overall operational efficiency. The method is demonstrated using a case study of the Port of Ramsgate (UK), where estimated results are compared with real-world data for validation. Finally, the study outlines theoretical and managerial implications and suggests directions for future research.

Navigation locks enable vessel transit between separated water bodies but also induce water exchange, leading to saltwater intrusion. During droughts, operational strategies that limit this intrusion cause vessel delays. Consequently, accurate estimation of the salt intrusion is essential for optimising these strategies. Current analytical lock exchange models, such as the Sea Lock Formulation, are a suitable and computationally efficient option for this purpose. However, the performance of these models relies on scarce gate-status data of the lock operation. To overcome this challenge, we present a novel method integrating the Sea Lock Formulation with the nautical traffic model OpenTNSim to derive time-varying lock operation parameters from accessible vessel data. This approach uniquely enables simultaneous evaluation of mitigation strategies on both saltwater intrusion and traffic performance. Applied to the world’s largest lock at IJmuiden, the model is validated against measured salt concentration and operation records. When forecasting, our method significantly improves the accuracy of the analytical models, reducing long-term salt intrusion errors from (Formula presented) % to (Formula presented) %. This marks a critical advancement toward a systematic exploration of tradeoffs between hydraulic and nautical objectives, enabling, for the first time, integrated lock management strategies that balance hydraulic protection with nautical efficiency in closed waterway systems.

The inland waterway transport sector is facing increasingly stringent legislation to reduce emissions and improve energy efficiency. Speed planning has the potential to provide logistically compliant, energy-efficient, and emission-reducing voyages for inland vessels. However, current speed planning methods do not consider PM and NO_x emissions, nor do they consider alternative power systems to internal combustion engines (ICE) and full electric systems. These omissions have led to a lack of clarity on the impact of speed planning on the emission profile of inland vessels and the impact of alternative power systems on energy consumption. In this paper we propose a validated speed planning method that considers the emission profile (CO₂, PM₁₀, and NO_x) and different engine types for inland vessels in an leg-based speed planning approach while taking into account varying fairway water depth and speed. Through a use case we show that the vessel can achieve a 7.26% energy, 5.37% CO₂ and fuel, 3.85% NO_x, and 6.77% PM₁₀ reduction while maintaining the same arrival time; showing a distinct difference of this method compared to slow steaming. We also find that CO₂, NO_x, PM₁₀, and energy are not directly proportional when making speed adjustments. Finally, we analyze the adverse effects of emission control areas and emission limits on the energy consumption and arrival times of vessels with non-zero emissions propulsion.

Policymakers in the maritime sector face the challenge of designing and implementing decarbonization policies while maintaining safe navigation. Herein, the inland sector serves as a promising stepping stone due to the possibility of creating a dense energy supply infrastructure and shorter distances compared to marine shipping. A key challenge is to consider the totality of all operational profiles as a result of the range of vessels and routes encountering varying local circumstances. In this study, we use a new scheme called “event table” to transform big data on vessel trajectories (AIS data) combined with energy-estimating algorithms into shipping-emission outcomes that can be evaluated from multiple perspectives. We can subsequently tie observations in one perspective (for example, large-scale spatial patterns on a map) to supporting explanations based on another perspective (for example, water currents, vessel speeds, or engine ages and their contributions to emissions). Hence, combining these outcomes from multiple perspectives and evaluation scales provides an essential understanding of how the system works and what the most effective improvement measures will be. With our approach, we can translate large quantities of data from multiple sources into multiple linked perspectives on the shipping system.

Inland waterway transport (IWT) is increasingly recognized as a cleaner, more efficient alternative to road transport for freight movement. However, the successful adoption of zero-emission fuelsparticularly hydrogen and battery power-depends on the strategic location and capacity of bunkering and charging stations. This extended abstract presents a multi-stage framework that combines simulation and mixed-integer optimization to identify where and how these stations should be deployed. First, a simulation model estimates the fuel consumption of vessels under varied waterway conditions, vessel dimensions, and hydrodynamic influences. Next, an optimization module, modeled within the supply chain, aims to minimize capital and operating expenses while ensuring sufficient fuel availability. Strategically placing multi-fuel stations in high-demand locations reduces infrastructure redundancy and ensures flexible operations. This study underlines the critical role of well-planned bunkering infrastructures and highlights the potential for future expansions in zeroemission vessel networks.

Navigation locks are complex structures crucial for water management. While locks facilitate vessel passages over essential hydraulic structures, they also form bottlenecks in water transport systems by inducing vessel delays. Furthermore, lock operation can impact freshwater availability, as freshwater is lost and saltwater intrudes. Consequently, during droughts, authorities often impose ad-hoc operational countermeasures to reduce these impacts. However, these impacts are often not quantified, potentially leading to ineffective measures or excessive vessel delays. To enhance decision-making regarding these countermeasures, we present a simulation-based method that jointly quantifies lock vessel delays, freshwater loss, and saltwater intrusion. Using geospatial, vessel, and hydrodynamic data, we apply the method to the sea lock complex on the route to the Port of Amsterdam, demonstrating its validity and effectiveness in a real-world setting. By testing various countermeasures, we conclude that vessel clustering based on maximum waiting time is most effective in reducing saltwater intrusion while keeping vessel delays acceptable, outperforming the common practice of limiting lock operation hours. Although further improvements are possible, the current method enables objective decision-making regarding resilient lock operation strategies worldwide in light of climate change.

The concept of circularity is used as an alternative to linear flow materials in order to protect the environment from potential damage. To determine to what extent a sediment management project contributes to circularity practices, it is necessary to quantify how much of the dredged material is maintained within the system. Hence, defining boundaries for the system and circularity indicators for dredged material plays a vital role in measuring the circularity level of a certain project [1]. This study concentrates on defining circularity indicators for sediment management projects when a certain amount of material is diminished during the pre-processing stage. Besides, the perspectives of different stakeholders (e.g. port authorities, and dredging contractors) influence the selection of strategies for circular maintenance dredging [2].

Inland waterway transport (IWT) is a key function of river systems worldwide. It is vulnerable to climate change, specifically to discharge extremes, and competes for water with multiple other functions. A clear framework describing its interests to inform decision-making during regular conditions as well as during climate extremes is as yet unavailable in the literature. To address this gap we examine how inland shipping is taken into account in waterway policies in the Netherlands. We apply the frame of reference method to ‘objectify’ current inland waterway transport (IWT) policies, addressing the themes of waterway capacity, safety, service level, and sustainability. By ‘objectifying’ we mean turning the implicit into an explicit ‘object’ of study on the one hand and revealing underlying ‘objectives’ on the other. We show that policies for waterway capacity and service level are well developed, while waterway safety policies are more implicit, and waterway resilience lacks a quantitative decision framework. We furthermore show that current policies mainly focus on regular conditions, leaving it unclear what changes under extreme river discharge conditions. The results provide important insights into shipping-related decision challenges during climate extremes, highlighting aspects that should be developed further to improve the climate resilience of inland shipping. While some of these implications are specific to the Dutch case, the method applied here can also be used for other river systems that support multiple functions.

The increasing amount of activities at sea, including the development of offshore wind parks, result in a more confined space for shipping, requiring the assessment of risk changes regarding nautical safety and the design of potential mitigation measures. The main contribution of this paper is the transparent evaluation of allision probabilities, based on an event-based approach. This enables a structural consideration of conditional probabilities, and supports uniting quantitative and qualitative analyses. The event-based approach allows evaluating the outcomes from various perspectives: scales, conditions, behaviour and dependencies. The analysis outcomes are represented in a concept called “event table”, from which these perspectives can be extracted. Consequently, from this single data structure, insights can be gained ranging from spatial variations of the risk (highly detailed or global patterns), to detailed distinction between the most important influencing factors (varying from vessel type to environmental condition). It is furthermore possible to switch between wind-park specific risks and assessment of operational and strategic risk-mitigating measures for the entire area. The core feature of incorporating multiple perspectives not only allows various views on the safety risks, providing a better understanding of the most important contributing factors, as well as effectiveness of intervention measures. Our analysis shows the added value of additional distance between shipping lanes and wind parks in the spatial design, and we demonstrate how our multi-perspective approach supports the strategic and operational decisions around the availability and deployment of emergency response vessels.

Climate change and socioeconomic developments have led to highly stressed estuarine systems in which dissimilar and conflicting stakeholder interests can no longer be satisfied simultaneously, inevitably resulting in trade-offs. Since translating these stakeholder interests into quantifiable performance indicators is challenging, policy and decision-makers are often bound to qualitative trade-off assessments, potentially resulting in suboptimal system interventions. In this paper, we assess the well-known socioeconomic trade-off in estuaries worldwide: port accessibility versus freshwater availability. We consider the severely dry year of 2022 in the Rhine-Meuse Delta, for which we assess the effects of bed level change. To quantify the trade-off, we apply a general framework of performance indicators determined based on models that use the output of a validated hydrodynamic model, including salt transport. Port accessibility was quantified based on vessel waiting times, using a data-driven nautical traffic model. For the performance indicator of freshwater availability, we developed a metric that includes storage capacity. The method resulted in a trade-off curve showing improved freshwater availability and deteriorated port accessibility for decreasing bed level. This trade-off curve provides valuable insights into system interventions in a multidisciplinary setting, being an intuitive visualisation showcasing the (non-monetary) benefits and costs for different stakeholders with dissimilar interests. As the method could be expanded and applied further, this study aids quantitative policy and decision-making.

The increasing frequency of extreme weather events poses significant challenges to inland waterway transport, a vital mode of port-hinterland connectivity in Europe. Low water levels disrupt vessel operations by reducing their transport capacity. This study investigates the potential of transfer hubs along the Rhine-Alpine corridor to address this challenge and maintain efficient cargo flows during drought conditions. It offers a replicable methodology for evaluating hub placement and transport resilience, incorporating multi-criteria decision-making and transport modeling. Using a transport competition model, three scenarios, including baseline, drought, and transfer hub application, are simulated to evaluate the cost-effectiveness of implementing these hubs at strategic locations. The integration of hubs, particularly near Duisburg and Andemach, demonstrated the potential to sustain 80% operability during disruptions by enabling modal shifts and alleviating bottlenecks. While competition in the North-Western European hinterland, involving ports such as the Port of Rotterdam, Hamburg, and Antwerp, is further intensified by climate-induced disruptions, our results show that transfer hubs can help ports secure their competitive advantages by ensuring reliable cargo flow under adverse conditions. Our findings highlight the strategic importance of transfer hubs in mitigating climate impacts, enhancing port competition, and supporting sustainable hinterland logistics.

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.

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.

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.

Extreme precipitation and droughts cause discharge variations in river systems, which impact Inland Waterway Transport (IWT). Disrupted hinterland connections affect the performance of sea and inland ports, which, in turn, may disrupt (global) maritime supply chains with far reaching economic effects. The prolonged drought of 2018 in North-western Europe, for example, caused significant economic losses for Germany’s industry. The reduced IWT capacity affected the production of energy, steel and chemical products. Discharge extremes reduce the reliability of IWT. To prevent an undesired modal shift to road or rail, water transport networks need to become more climate resilient. We believe that to date IWT has received relatively (too) little attention in climate resilience studies, and measures have often been proposed from an oversimplified perspective. Furthermore, rivers and canals support multiple user functions, so IWT measures should be evaluated against other functions, and vice versa. This paper discusses a novel method to better account for IWT, using a systemic perspective and an integral approach.

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.

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.

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.

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.

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.