For 50 years and more than 160 issues, Terra et Aqua has benchmarked innovative maritime solutions. Articles are available here as well as in IADC’s Knowledge Centre.

Published March 2024

Terra et Aqua 173: complete issue

The spring issue includes articles on a new method to economically evaluate adaptation pathways, optimising real-time dredge monitoring systems with acoustic sensors and dealing with computational innovation in dyke reinforcement projects.

Optimising real-time dredge monitoring systems with acoustic sensors

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.

Editorial: Knowledge is king

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.

Dealing with computational innovation in dyke reinforcement projects

Authors: Joppe Vugts
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.

A new method to economically evaluate adaptations pathways

Authors: Maria Montijn
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.
Published December 2023

Terra et Aqua 172: complete issue

The autumn issue includes articles on Boskalis’ Safety Award winning water box design, a study on slurry transport characteristics in a jet pump and the modernisation of the Świnoujście – Szczecin Fairway project.

Study of slurry transport characteristics in a jet pump

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.

Boskalis eliminates risk of implosion with new design for water box

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.

Modernisation of the Świnoujście – Szczecin fairway

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).
Published October 2023

Terra et Aqua 171: complete issue

The autumn issue includes articles on integrating dredging in sustainable development, sand as a resource and submissions for IADC’s Safety Awards 2023.

Integrating dredging in sustainable development

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.

Finding innovative solutions to improve safety

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.

Sand as a resource: Best practices to conduct responsible dredging projects

On 5 September 2023, IADC published a paper by the same name in response to a 2022 United Nations Environmental Program (UNEP) report “Sand and sustainability: 10 strategic recommendations to avert a crisis”. In this report, UNEP calls for actions to set the global sand agenda in addressing environmental needs alongside justice, equity, technical, economic and political considerations. IADC’s paper highlights the dredging industry’s best practices for optimal use of scarce sand resources. This article is a condensed version of that paper.
Published June 2023

Terra et Aqua 170: complete issue

The summer issue includes articles on simulating for sustainability: alternative operating strategies for energy efficiency, evaluation of a nature-based agitation dredging solution and waste heat recovery on dredging vessels.

Waste heat recovery on dredging vessels

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.

Evaluation of a nature-based agitation dredging solution

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.

Simulating for sustainability: alternative operating strategies for energy efficiency

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.
Published March 2023

Terra et Aqua 169: complete issue

The spring issue includes articles on applying early contractor involvement in marine infrastructure procurement, the importance of flocculation in dredge plume modelling and reinforced soil – the quay wall structure for the future?

Applying early contractor involvement in marine infrastructure procurement

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.

The importance of flocculation in dredge plume modelling

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.

Reinforced soil – the quay wall structure for the future?

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.
Published December 2022

Terra et Aqua 168: complete issue

The winter issue includes articles on the regulation and management of marine aggregate dredging in England, the Fehmarnbelt tunnel trench dredging project, deploying private capital to accelerate the green transition and the winner of IADC’s Safety Award 2022.

DEME’S award winning retractable ladder design

DEME is very proud that its retractable ladder, specifically designed for hydraulic track excavators, won the prestigious IADC Safety Award 2022, and especially because the design of this invaluable piece of safety equipment is now being shared with other IADC members.

Regulation and management of marine aggregate dredging in England

Marine dredged sand and gravel make an important contribution to regional supplies of building materials used in England. Marine aggregate dredging however, is known to result in effects to the receiving environment which, if not properly controlled, could cause adverse impacts to a wide range of receptors. As the marine area around England gets busier, competition for space comes with regulatory challenges and an integrated marine management approach that uses a robust planning system is required. This article discusses the regulation of aggregate dredging in England and provides an overview of the sector’s importance in providing primary aggregate.

The Fehmarnbelt tunnel trench dredging project

A fixed and direct transport connection between Scandinavia and Central Europe has been an enduring vision for many decades. This vision is about to be realised with the construction of the Fehmarnbelt Fixed Link, an 18-kilometre-long immersed tunnel between Rødbyhavn in Denmark and Puttgarden in Germany. When it opens in 2029, the tunnel will be the longest immersed tunnel in the world combining a dual railway and motorway connection. This article provides insight into the improved dredging equipment used and the methodology specially adapted and further developed to the project’s requirements.

Deploying private capital to accelerate the green transition

Authors: Arjan Hijdra
Green solutions in ports, waterways and coastal projects have increasingly become available thanks to many years of research and pioneering efforts in practice. These sustainable and/or nature-based solutions have shown to be good alternatives for classic solutions, but application is far from mainstream yet. One of the major hurdles is the lack of access of private capital to finance these kinds of solutions despite the strong interest of capital markets in green infrastructure opportunities. Identifying the hurdles and paving a way forward to overcome these hurdles could therefore help to increase the uptake of those green solutions.
Published September 2022

Terra et Aqua 167: complete issue

The autumn issue includes 11 submissions in the running for IADC’s Safety Awards 2022, an article on a web-based global mapping tool to anticipate the hazard of flooding around the world, and research from Suman Sapkota, the winner of IADC’s Young Author Award 2022, on sediment erosion wear on the impeller blades of a centrifugal dredge pump.

Estimating sediment erosion of a centrifugal dredge pump’s impeller

Sediment erosion is a phenomenon of mechanical wear of components that decreases efficiency and uptime of the dredging process. Dredge pumps are designed to handle mixtures of water and solid particles with varying particle size from less than 0.002 mm to greater than 200 mm. A dredge pump’s overall effectivity in the field depends upon its uptime. Uptime is influenced by the number of times the pumping process is interrupted, which can be due to maintenance combating the material loss, clogging, etc. This research deals with the erosion phenomena by considering a framework of numerical models, capable of qualitative and quantitative erosion estimation, coupled with experiments for validation. Coordinate Measurement Machine (CMM) is used for surface roughness measurement before and after the experiment, thus depicting the material loss due to erosion.

Submissions for IADC’s Safety Awards 2022

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 2022 Safety Awards, IADC’s Safety Committee received 11 submissions. Each one is assessed on five different categories; sustainability; level of impact on the industry; simplicity in use; effectiveness; and level of innovation.

Climate Risk Overview tool: mapping naturebased flood protection opportunities

The planet is facing enormous challenges caused by human activity, increasing the vulnerability of communities and ecosystems to the forces of nature. This is worsened by the effects of climate change, which is threatening the world’s coastal defences. Van Oord has responded to these challenges by developing the Climate Adaptation Action Plan. The plan is designed to encourage meaningful dialogue between stakeholders in order to provide ready-to-scale marine solutions that help increase the resilience of the communities and ecosystems of coastal areas.
Published May 2022

Terra et Aqua 166: complete issue

Read the complete issue containing articles, upcoming events, an interview and book review.

Interview: Marsha Cohen – Editor-in-chief for quarter of a century

As IADC celebrates 50 years of its quarterly journal, it seemed only fitting to speak to its longest standing editor, Marsha Cohen, who stood at the helm of Terra et Aqua for 25 years. We caught up with her at her home in Florida to talk about the highs, the lows and a good dose of serendipity.

50 years of case law that transformed marine infrastructure contracts

Authors: David Kinlan
This article reviews various court cases over the past 50 years and considers their influence on marine infrastructure contracts and the allocation of risk between contract parties. The establishment of case law and legal precedent is an ever-evolving process, it being dependent on claimants to put their disputes through the court process to seek the outcome they desire. It is often a long and costly process. The rise of adjudication in various common law jurisdictions and countries means that often disputes are resolved without recourse to the courts and various industry standard contracts have arbitration as the final and binding mechanism to resolve disputes.

Building a proactive safety culture within a marine contractor organisation

It is hard to imagine a time when safety was not deemed important, when Personal Protective Equipment (PPE) was not used and little was done in the way of prevention. A few decades ago, occupational health and safety was not considered as important for the vast majority of companies. Instead, incidents and emergencies were handled as they occurred, as effectively as possible given the limited technology and resources available. Today, those times have changed. This article explores the progress of health and safety in the dredging industry and QHSSE professionals, Ton van de Minkelis and Christophe Leroy share their experiences in building a proactive safety culture.

Young Author Award winners: Where are they now?

Each year, at selected conferences, the Conference Paper Committee is asked to recommend a prize winner whose paper makes a significant contribution to the literature on dredging and related fields. Since 1987, IADC has presented 42 Young Author Awards. Curious to see where they are now, we asked previous winners what impact winning the award had on them and their career.

Pipeline design – density wave amplification and slurry dynamics

The effect of density waves and slurry dynamics on slurry pipeline flow assurance cannot be predicted with current slurry pipeline design methods. Current methods are based on steady-state assumptions, assuming that the mixture velocity and density are constant in time and in the pipeline. Therefore, using current design methods a dynamically stable pipeline cannot be guaranteed. Furthermore, new experiments in vertical pipelines show that density wave amplification is possible at mixture velocities far above the critical velocity. This article presents a new temporal design method based on 1D Driftflux CFD, which is able to model growing density waves.

Shaping the engineers of tomorrow

During his distinguished career as professor of Coastal Engineering at Delft University of Technology (TU Delft), Kees d’Angremond served as head of Hydraulic and Offshore Engineering, chair of the department of Hydraulic and Geotechnical Engineering, and dean of the faculty of Civil Engineering from 1989 to 2001. Now professor emeritus, he still works as an advisor and independent consultant. We invited Kees to a conversation with Stefan Aarninkhof, professor of Coastal Engineering and chair of the department of Hydraulic Engineering at TU Delft, to talk about their careers in the dredging industry and the role of academia in the industry today.
Published December 2021

Terra et Aqua 165: complete issue

Read the complete issue containing articles, upcoming events, an interview and book review.

The impact and costs of Building with Nature projects

The use of nature and natural processes is an innovative way to increase water safety and create added value through nature development and recreation. This exploratory study provides an initial inventory of the impact and costs of existing Building with Nature projects in the Netherlands. It also includes an analysis of the decision-making process in choosing this type of project and identifies success factors. Building with Nature projects deliver added value but often also involve additional costs compared to traditional reinforcements. These costs give an indication of what we as a society are prepared to pay for the development of nature and recreation as part of hydraulic engineering projects.

Keppel Offshore & Marine’s Safety Plus Programme

IADC’s Safety Committee and Board of Directors awarded the very first Safety Award to a supply chain organisation active in the dredging industry to Keppel FELS. The company was praised by the committee for the results of its safety programme and commitment to safety onsite. Anchored in Keppel Offshore & Marine’s Safety Plus Programme and Singapore's National WSH Vision 2028, Keppel FELS continues to consistently improve and enhance its existing Health, Safety and Environment (HSE) management systems.

Jan De Nul crew invents innovative bollard step

During marine transfers, it is essential to achieve a maximum level of control. With the bollard step, Jan De Nul has designed a simple solution to enhance safety during transfers of crew and visitors. This innovative idea came from the crew of the multicat DN46 and was picked up during an Operational Control meeting, where an advisory board discusses suggestions that improve the safety and efficiency of the company’s operations. ‘We stimulate all possible innovative ideas within our company’, says Quinten Schaumont, Area QHSSE advisor. ‘At all levels, at all times.’

The valuation of externalities in maritime infrastructure projects

Climate change and increasing environmental damage are demonstrating the urgency of transformation to a sustainable global economic model. The implementation of the sustainable development concept tends to narrow to integrating environmental, social, and economic concerns in the decision making. In economics, the definition of such concerns is an externality that represents the divergence between social and private costs. This study investigates the available sustainable asset valuation methods that can include the externalities materialised in maritime infrastructure projects and compares them based on economic, social and environmental criteria.

The responsible project: A view on social licence

In today’s world, expectations for sustainable practices are fast becoming the norm. Countries, the public and communities are requesting transparency, the application of higher environmental standards and involvement in decision-making processes when new developments in a marine environment are proposed. Marine infrastructure projects not only require environmental permits and works licences to be in place, they also need a Social Licence to Operate (SLO). This article describes the social licence in this fast-changing context of information and technology, and explores tools that can be used to develop a ‘responsible project’ and provide a successful and sustainable outcome for society and the environment.

Editorial (Winter 2021)

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.
Published September 2021

Terra et Aqua 164: complete issue

Read the complete issue containing articles, upcoming events, an interview and book review.

Editorial (Autumn 2021)

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.

Applying the ecosystem services concept in marine projects

A full consideration of ecosystem services (ES) impacts, interactions and improvements can result in more sustainable and adaptive solutions for dredging and marine construction projects. Furthermore, the benefits can be translated in monetary terms, providing returns on investment and highlighting the links between ecology and economy. For some however, the ES concept is too theoretical. This article seeks to show how the ES concept can actively be applied at any point during a project and the benefits of doing so. Its purpose is to provide a framework for integrated and interdisciplinary thinking throughout the different steps of the project cycle.

Finding innovative solutions to improve safety

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 2021 Safety Awards, IADC's Safety Committee received 15 submissions. Each one is assessed on five different categories; sustainability; level of impact on the industry; simplicity in use; effectiveness; and level of innovation.

Study of greenhouse gas emissions during ripening of dredged marine sediment

As increasing greenhouse gas (GHG) emissions contribute to global warming, it is becoming more important to consider the carbon footprint of hydraulic engineering projects. This carbon footprint is more complex than previously thought however, as it can also include the carbon dynamics of the sediments from which projects are built. The purpose of this study was to provide a first approximation from sediment-related GHG emissions of dredged sediments. Using the case study of the clay ripening pilot project (‘Kleirijperij’) in Groningen, the Netherlands, one phase of sediment processing was examined: the ripening of dredged sediments for use as a clay material in dyke construction.

Balancing project progress and limited system knowledge in Amatique Bay

The development of a new marine project demands a system approach in which all aspects, including technical, economic, environmental and social, are considered and integrated equally and at an early stage. While insufficient information may be available to make informed decisions, choices need to be made to progress a project, assess impacts and risks, and engage stakeholders. This article explores the case of a new port terminal in Amatique Bay, Guatemala. A method was developed to assess, at an early stage, the potential negative impacts on seagrass habitats from the disposal of dredged material at different locations, while having limited real-time and location-specific information at hand.