Frank Verhoeven, President of IADC, shares his thoughts on today’s issues related to the dredging industry and introduces the articles in this issue of Terra et Aqua.

In arbitration or court proceedings, the role of an expert witness is crucial, especially in a specialised field such as marine infrastructure and dredging. An effective dredging expert witness can significantly influence the outcome of a case by providing clear, unbiased and well-supported testimony. This article explores what makes an effective dredging expert witness, their duties to the tribunal, what to look for when selecting an expert, common mistakes made by experts and lessons from two notable expert witness cases.

On 1 November 2025, I stepped into the role of Secretary General of the International Association of Dredging Companies (IADC). In many ways, it felt like the natural continuation of a journey that started long before I ever imagined a career in dredging. My fascination with water, the maritime world, engineering and, above all, teamwork has shaped every decision I have made, from my earliest days in the Sea Scouts to becoming a naval architect and, later, an association professional. Looking back, each chapter prepared me for this new responsibility: helping guide an industry that shapes coastlines, protects communities and keeps global trade moving. This article reflects on that journey and shares my perspective on where our industry is headed. It is also the story of how I found myself “stuck in the mud,” why I am grateful for it and why I believe dredging is more essential than ever.

Reservoirs are critical elements of global water infrastructure, supporting water supply, flood protection, hydropower generation and ecological functions. Their long-term performance, however, is increasingly undermined by sedimentation – a slow and often overlooked process that reduces storage capacity and disrupts natural sediment continuity along river systems. This article examines sedimentation as a key sustainability challenge for reservoirs and impounded waters. It outlines the causes and impacts of sediment trapping, from declining reservoir capacity to downstream river and delta erosion, and explains why proactive sediment management is essential. The article concludes by presenting continuous sediment transfer as a sustainable approach to maintaining reservoir functionality while restoring sediment continuity.

The Port of Sohar, located in the Gulf of Oman, is constructing a jetty close to a critical industrial seawater intake. The project includes capital dredging of a navigation channel, turning circle and berth pocket, where turbidity control is essential to protect water supply operations. A pre-tender assessment identified potential exceedance of turbidity limits under unfavourable conditions, leading to strict permit requirements. To address this, a turbidity forecasting model was developed to support daily operational decisions. Using wind, tides, dredging plans and soil properties, the model enabled proactive, adaptive dredging while maintaining compliance and optimising productivity.

Frank Verhoeven, President of IADC, shares his thoughts on today’s issues related to the dredging industry and introduces the articles in this issue of Terra et Aqua.

Sometimes a small improvement can have a huge impact. Van Oord’s new reclamation pipe gasket design significantly reduces the risk of potential finger injuries with an easy to implement and cost-effective solution. The design was chosen as the winner of IADC’s Safety Award 2025.

Dredging of rock using a cutter head as found on a cutter suction dredger will become increasingly more important as drilling and blasting is often prohibited. Understanding the cutting process and resulting forces on the chisels can lead to improved design and operational efficiency. The majority of experimental and numerical work performed considers rock cutting with an unworn or sharp chisel, often omitting the normal force. This article presents the linear rock cutting setup developed by Royal IHC to study the effect of a worn or blunt chisel geometry on the cutting forces, with the emphasis on the normal force.

Many ports and harbours operate in and around marine coastal habitats, such as tidal marshes, mangrove forests and seagrasses. Many of these marine coastal habitats are considered blue carbon ecosystems, which play a crucial role in capturing carbon. This article examines how waterborne transport infrastructure impacts blue carbon ecosystems, reviews current mitigation strategies and suggests integrated approaches for sustainable coexistence. We emphasise the importance of collaboration among marine transport authorities, environmental managers, scientists and engineers to protect these essential carbon sinks while supporting the sector's economic contributions.

When individual employees, teams and companies view everyday processes and situations through a continuous lens of safety, they can each contribute to making all aspects of operational processes, whether on water or land, safer. For this year's Safety Award, IADC's Safety Committee received 14 submissions. Each one is assessed on five different categories; sustainability; level of impact on the industry; simplicity in use; effectiveness; and level of innovation.

Frank Verhoeven, President of IADC, shares his thoughts on todays’ issues related to the dredging industry and introduces the articles in this issue of Terra et Aqua.

Seagrass restoration is increasingly recognised for its potential to enhance biodiversity and contribute to carbon sequestration. However, planting methods are largely based on manual techniques, posing challenges for upscaling and implementation as nature-based solutions (NbS) within the dredging industry. To address this, techniques to combine sediment nourishments with seed-based seagrass restoration are explored. Seed settlement behaviour is investigated via laboratory experiments, analysing seed settling velocities and distribution in various sediment concentrations, revealing the importance of grain size and sediment dynamics. These findings lay the groundwork for innovative, large-scale restoration techniques leveraging traditional dredging methods, with pilot projects planned for 2025.

Dredging and reclamation projects have played an important role in the UAE’s rapid development, meanwhile efforts are continuously made to balance progress with marine ecosystem conservation. This paper explores the development of fish domes and 3D-printed artificial reefs, highlighting their role in providing marine habitats, promoting biodiversity and supporting sustainable development. Case studies from Abu Dhabi region demonstrate the effectiveness in restoring marine environment. By integrating innovative reef structures with sustainability goals, the UAE ensures that economic growth aligns with environmental conservation, fostering a resilient marine ecosystem for future generations.

The Netherlands has almost 4,000 km of dykes. Over the past decades, a significant amount of clay has been used within these dykes for reinforcement. This layer of clay is essential as water barrier and to prevent the construction from collapsing due to erosion. Clay of the right quality is becoming less and less available, particularly because the usage requires a minimum thickness of 1.0 to 2.0 metres. Therefore, alternative materials such as Trisoplast are being researched as a suitable replacement for clay.

Reservoirs are large natural or artificial lakes created by constructing a dam to store fresh water. Sedimentation in a reservoir both diminishes its storage capacity and compromises its purpose and safety. Reservoir dredging is a curative sediment management strategy, which, if planned effectively, is a sustainable solution. Most reservoirs have multiple users leading to competition and potential conflicts among user groups. Reservoirs are associated with complex and sensitive ecosystems and large volume of sediments that need to be removed. A risk-based approach for reservoir dredging involving all stakeholders from an early stage will help to identify and mitigate risks with minimal damage to the associated ecosystems.

When individual employees, teams and companies view everyday processes and situations through a continuous lens of safety, they can each contribute to making all aspects of operational processes, whether on water or land, safer. For the 2024 Safety Awards, IADC's Safety Committee received 14 submissions. Each one is assessed on five different categories: sustainability; level of impact on the industry; simplicity in use; effectiveness; and level of innovation.

Cutter head repairs in the dredging industry have long been associated with significant safety risks, such as falls and musculoskeletal injuries due to awkward working postures and the need for lifting. Jan De Nul’s latest cutter head staircase design addresses these challenges by offering a more straightforward and safer solution.

The availability of suitable sand has become a limiting factor in the development of many ambitious reclamation projects, making the reuse of existing, less suitable materials a critical solution. This subject has been given broader international attention in the past years driven by the shortage of sand resources and by the desire for a more circular society where waste does not exist. So far, only a few examples exist of islands that have been constructed with fine silty or even clayey sediment. In this context, the reclamation with sediments must evolve from an exceptional case requiring special considerations, to a common practice. To favour this practice, an integrated framework is needed where the concepts of suitable and unsuitable are redefined.

Frank Verhoeven, President of IADC, shares his thoughts on todays’ issues related to the dredging industry and introduces the articles in this issue of Terra et Aqua.

Dredging and reclamation projects can significantly impact local ecosystems. Negative impacts can be minimised by adopting proper environmental management and mitigation, from preparation to completion phase. Addu City project sets an example of implementing novel construction methodologies and successfully addressing environmental challenges. The project has created over 200 hectares (ha) of climate resilient land for housing and touristic development. Enclosure of footprints, relocation of corals and seagrass (at pilot level) before reclamation process, and monitoring sediment impact in the nearby marine protected areas during dredging and reclamation are exemplary of the management approach applied to ensure minimisation of potential negative environmental impacts.

Environmental management and monitoring programmes are essential for identifying and mitigating adverse impacts that dredging activities may have on the environment. However, it is not always feasible, especially for the client, to have the necessary tools to conduct these tasks adequately, whether due to cost constraints or limited information availability. The use of the Automatic Identification System (AIS), as an efficient and cost-effective monitoring method in dredging projects, can lead to significant improvements in project environmental management. In cases involving trailing suction hopper dredgers (TSHD), this tool allows for equipment tracking, verifying the proper use of contract-approved areas and additionally estimating daily production values through a simplified method.

Dune erosion due to storm surges and severe wave attack is the primary failure mechanism of sandy sea defences. At a curved coastline, dune erosion is greater than at a straight coastline. However, how much higher is often difficult to predict. This article presents a comparison of field observations and model results of the response of the Maasvlakte 2 curved sandy sea defence to storm attack.

Frank Verhoeven, President of IADC, shares his thoughts on todays’ issues related to the dredging industry and introduces the articles in this issue of Terra et Aqua.

Driven by an increasing population, global maritime trade activity is at an all-time high. To keep up with demand, larger vessels and expanded port facilities are being built. Larger vessels, particularly container vessels, often require multiple expansion projects, such as expanding turning basins, widening shipping channels and digging deeper berths. These port expansion projects often require dredging to ensure the upgraded facilities can handle vessels of any size. However, dredging in the maritime industry is continuous, expensive and resource intensive. To meet evolving demands while remaining economically viable, tools that increase dredging efficiency need to be evaluated and incorporated into dredging operations.

Frank Verhoeven, President of IADC, shares his thoughts on todays’ issues related to the dredging industry and introduces the articles in this issue of Terra et Aqua.

Since 2023, the Dutch government no longer prescribes which calculation models must be used in the assessment of dykes. The water boards themselves must determine which method they use to calculate the probability of flooding. This enables the development of calculation innovations. Following various dyke assessments, the largest safety risk is caused by the failure modes of slope stability and piping, therefore substantial investment is being made to better understand these failure modes. In our research, we found a way to deal with computational innovation in dyke reinforcement projects by applying specific innovations and looking at their general implementation.

The consequences of climate change are becoming more apparent and mitigation measures alone are no longer sufficient to prevent its impact. Investing in adaptation measures has become inevitable. However, the uncertain future conditions and the high associated investment costs puts pressure on making the best choice. Adaptive pathway planning is considered as a promising approach to develop flood risk reduction strategies that can adapt to changing circumstances. However, limitations in the existing evaluation methods pose challenges in the choice for the best strategy.

Frank Verhoeven, President of IADC, shares his thoughts on todays’ issues related to the dredging industry and introduces the articles in this issue of Terra et Aqua.

In this study, the computational fluid dynamics (CFD) analysis method was used to simulate the mixing and transportation  characteristics of water and mud in a jet pump. By observing the fluid mixing law in the mixing chamber, throat and other structures,  the internal flow field distribution of the jet pump under different working conditions was compared and studied. As a result, the internal flow details and operation performance curves of a certain size jet mud pump were obtained. It provides theoretical support  for the optimisation design of a slurry jet pump in dredging engineering.

Alongside pumping sand, managing the water level in the landfill is an important aspect of a dredging project. A water box, a metres-high structure in which planks can be positioned manually to keep the water at the desired level, is indispensable for this work. Boskalis recently won the Safety Award of the International Association of Dredging Companies (IADC) for its new, modular and, above all, safer design that eliminates the risk of incidents.

The idea of a modern maritime access route from the Baltic Sea to the Port of Szczecin in Poland was already born towards the end of 20th century. Quay walls in the neighbouring Port of Police, built in the 80s, were already constructed to accommodate a depth of 12.5 metres and initial modernisation works commenced in the early 90s. On 28 September 2018 the “Modernisation of the Świnoujście – Szczecin Fairway to a depth of 12.5 m” became a reality with the signing of the design and build contract between the Maritime Office Szczecin and the DIVO consortium (Dredging International NV and Van Oord).

Frank Verhoeven, President of IADC, shares his thoughts on todays’ issues related to the dredging industry and introduces the articles in this issue of Terra et Aqua.

The International Association of Dredging Companies (IADC) aims to inform the world about the fundamental need for dredging as well as advocating for an industry that makes the world a safer, better and more sustainable place to live. Adapted from the second chapter of the book, Dredging for Sustainable Infrastructure (2018), this article presents the concept of sustainability in relation to dredging projects. It describes the approaches and practices that are key to using dredging and dredge material to create more sustainable solutions and infrastructure – a modern way of thinking about dredging.

When individual employees, teams and companies view everyday processes and situations through a continuous lens of safety, they can each contribute to making all aspects of operational processes, whether on water or land, safer. For the 2023 Safety Awards, IADC's Safety Committee received nine submissions. Each one is assessed on five different categories; sustainability; level of impact on the industry; simplicity in use; effectiveness; and level of innovation.

Limiting global warming requires the maritime sector to transition to a more efficient and sustainable operation. Reducing greenhouse gas (GHG) emissions, such as carbon dioxide and methane is vital to limit the global temperature rise (IPCC, 2021). Several legislative initiatives are in effect or are being discussed, including the IMO GHG strategy and the FuelEU Maritime initiative. This article discusses the potential of waste heat recovery (WHR) technologies to reduce the fuel consumption of dredging vessels. Available WHR technologies are compared based on working principle and operational performance for different types and ratings of internal combustion engines.

The challenge of maintaining harbours and ports while conserving and sustaining coastal habitats, with all the rich resources they provide, requires that port and harbours do more to develop approaches to maintenance dredging that provide benefit to these neighbouring habitats. In this article, we describe an example from Harwich Harbour in the UK where Harwich Haven Authority (the Conservancy Authority) is looking to move to a more nature-based maintenance dredging methodology, using agitation dredging. Using the results of monitoring and sophisticated numerical modelling, we evaluate the likely benefit to the Stour/Orwell intertidal areas arising from the use of the agitation dredging.

In the 2015 Paris agreement, countries committed to implementing measures to reduce greenhouse gas emissions to limit global warming. For the maritime industry specifically, the International Maritime Organization (IMO) has proposed measures for energy efficiency of vessels and candidate measures regarding fuel choice and speed optimisation. This article aims to contribute to the latter by showing how logistical simulations can be used to optimise fleet operations. We will illustrate this in the form of a conceptual case using one cutter and a range of barge fleets. Running simulations with all possible fleets, we will demonstrate the value of extra energy-based alternatives to challenge the fastest, cheapest and most flexible alternatives.

Frank Verhoeven, President of IADC, shares his thoughts on todays’ issues related to the dredging industry and introduces the articles in this issue of Terra et Aqua.

Frank Verhoeven, President of IADC, shares his thoughts on todays’ issues related to the dredging industry and introduces the articles in this issue of Terra et Aqua.

Complex construction projects that use traditional procurement practices are often impacted by significant cost overruns and delays. Early contractor involvement (ECI) is a concept that strives to involve the contractor collaboratively at an early stage of a project’s development to mitigate or otherwise eliminate those risks. In August 2022, PIANC published the report “A framework for early contractor involvement in infrastructure projects” to help industry practitioners in choosing and best implementing ECI. This article is intended to develop on key aspects of the PIANC report and look at the factors that can lead to a successful maritime ECI project.

Numerical models are often used to predict the magnitude and behaviour of dredge plumes to help assess and manage any environmental risks. To provide a realistic prediction of plumes resulting from dredging, numerical models require information on the rate at which sediment is suspended by the dredging, along with the characteristics of the suspended sediment. Previous investigations have shown that in the marine environment, fine-grained sediment suspended by natural processes and dredge-related activities are typically present as aggregated particles known as flocs. This article considers the importance of including the process of flocculation in dredge plume models.

Steel and concrete are the most common materials used in quay wall structures. The application of these materials contributes to a high emission of greenhouse gasses such as CO2 and the materials make up a large part of the construction costs. This graduate research examines whether alternative quay wall structures have the potential to be more cost effective and more sustainable compared to conventional structures for inland ports. An innovative quay wall of reinforced soil was designed and quay elements implemented to make a quay wall structure. A comparison was then made based on the criteria costs and sustainability between the innovative quay design and two conventional quays.