Taking a fresh look at traditional, unsustainable coastal defence methods. A pioneering project discovers some inspiring concepts, including using biogenic reefs for ecosystem-based flood defence.

‘It’s clear that the solutions that we employed in our approach to engineering in the 20th century are not aging well.’ As National Lead for the Engineering With Nature initiative, Dr Todd Bridges discusses how we must have a diversified solution set in which nature is a part of the solution.

A major mechanical property of clay is the adhesion factor that reflects the ratio between its cohesive and adhesive strength under different water content.

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.

Continuing the ‘seeing is believing’ approach, this second volume presents Engineering With Nature principles in action through 62 projects from around the world.

In the past decade, there have been noteworthy advances in case law with respect to adverse physical conditions as well as the development and use of digital ground models that have become more widespread. This article looks at the development and changes in risk profiles that may result due to these two developments.

Over the past decades, there has been a growing interest in exploring innovative ways to minimise the environmental footprint of coastal developments and in nature-based approaches for shoreline protection. At Mubarraz Island near Abu Dhabi (UAE), an international oil company beneficially reused ~12 million m³ of dredged material to protect pipelines, construct a causeway and create mangrove habitat to manage coastal erosion. This ‘Working with Nature’ approach has provided a cost-effective nature-based solution for shoreline protection, with added benefits for biodiversity conservation.

In June 2019, the research team of the LIFE MARINAPLAN PLUS project began operating the first-of-a-kind demonstration plant installation at the harbour entrance of Marina di Cervia (Italy). Fulfilling the project’s objective to apply at industrial scale a reliable technology for the sustainable management of sediment in marine infrastructures, this technology prevents harbour silting through the use of submerged devices called ‘ejectors’ installed on the seabed.

At Deltares in the Netherlands, a research team is developing a portfolio of technologies dedicated to the management of the finest and most challenging fraction of soft sediments. These technologies may unambiguously be called nature based because they make use of natural processes to enhance dewatering and strengthening, induce flocculation and the settling of fines, and protect the muddy bed from erosion.

Managing sediments, especially from dredging, is important for the management of estuaries and coastal areas. When implemented in the right way, a sediment management strategy can be qualified as a nature-based solution as it uses the physical processes of erosion and sedimentation to create added value. There is a need for an evaluation of sediment strategies and the habitats that are created for a wider range of objectives than only biodiversity and nature conservation. The concept of ecosystem services provides this broader framework.

Stéphanie Groen works as the Director of Coastal & Climate Change, Asia for Aurecon. Based in Singapore, she was appointed to the position at the beginning of 2020. Previously, Stéphanie was involved in marine and environmental projects for more than 15 years with DHI and her education is in civil engineering and business administration. IADC also knows Stéphanie as the winner of the Young Author Award in 2007. More recently, she was appointed as a committee member to the prestigious FIDIC Sustainable Development Committee. We were interested to hear more from Stéphanie – her views on sustainability, the collaboration with the dredging industry through FIDIC and what her new role can mean for sustainable water infrastructure projects.

At present too little use is made of the opportunities that the design and construction of land reclamation offer for the underground storage and recovery of fresh water. The managed aquifer recharge systems in the coastal dunes of the Netherlands are a good example of successful subsurface water storage. And it is to be expected that the sandy deposits of land reclamations could serve a similar purpose. This in turn will contribute to a sustainable development of land reclamations.

A surface plume from overflow can stay suspended for long periods and distances, resulting in negative environmental impact through increased turbidity and sedimentation. Generation of a surface turbidity plume from the overflow of a Trailing Suction Hopper Dredger is investigated by a process-based, detailed Computational Fluid Dynamics model.

As regular maintenance and relocation of sediment deposits are highly expensive, Port authorities seek more efficient solutions for reducing the costs and CO2 emissions of maintenance dredging. One solution, water injection dredging (WID), is carried out for maintaining the sediment deposits which predominantly consist of clay and silt. WID has been proven to be a cheaper solution by leaving the sediment in place, eliminating substantial costs for relocation of the dredged sediment.

Armed with degrees in both Marine Engineering and Engineering Economics as well as 35 years – and counting – of experience at the Panama Canal Authority, Ilya Espino de Marotta has blasted through the glass ceiling wearing a pink hard hat. Amongst the diverse roles she has under her belt, ranging from Marine Engineer in the shipyard to Vice President for Transit Business, Ilya has notably led the Canal’s expansion as head engineer and now oversees operations from the second highest position at the authority.

Self-weight consolidation plays a major role in the creation of land using mud, the ripening of mud layers and, also, in the storage of contaminated mud and slurries in ponds.

The international dredging and maritime construction industry remains quite devoid of the use of mediation as a tool for Alternative Dispute Resolution. Mediation is outlined to broaden familiarity with mediation, increase confidence in the process, and inform about the benefits it can bring to the industry at large.

‘Water is more than a toilet, tap, dam, dyke or levee, it's an enabler.’

Dredging is essential for the maintenance and development of ports, harbours and waterways to allow for safe navigation, remediation and flood management. The process, which relocates large volumes of sediment, can be accompanied by the release of suspended sediments into the water column referred to as sediment plumes.

Contracts for dredging and offshore works are diverse. Moreover, increasing financial and/or managerial constraints require contracting parties to change the apportionment of commercial risk. Contractors and suppliers have to adapt to contracts that are chosen unilaterally by the owner. Turnkey and engineering, procurement, and construction (EPC) contracts are becoming more common in the industry and bring their own benefits and challenges.

Can nature-based solutions be mainstream solutions? Nature-based solutions have obvious advantages but have not been embraced at wider scale. The barriers which can hinder wide-scale application and the topic’s relevance to the dredging community are discussed.

The Bacton Sandscaping scheme is a large-scale beach nourishment designed to protect the Bacton Gas Terminal from cliff and beach erosion while also reducing flood and erosion risk to the communities of Bacton and Walcott, buying the time they need for adaptation to coastal change.

This study examines which and, if possible, how much more ecosystem services are provided by the most recent nature inspired coastal protection project Prins Hendrik Zanddijk, in comparison with a traditional concrete and asphalt construction.

The nomination which won the IADC’s Safety Award 2019 was unveiled at IADC’s Annual General Meeting in New Delhi, India.

Situated in Muskegon, Michigan, the project provided numerous environmental benefits related to the remediation of legacy sediment contamination as well as restoration of the habitat into a more diverse wetland system.

Winning co-author Liesbeth De Keukelaere the Young Author Award, an article about the pilot test case organised at the Prins Hendrik Zanddijk project in Texel, The Netherlands, demonstrating drone technology for water quality monitoring.

Cables for offshore wind farms in the North Sea are buried for protection. A highly variable seabed topography influences the trenching process in sandy soils. A model has been developed to estimate the influence of sand dunes on the trenching process.

After 30 years at Witteveen+Bos, Henk Nieboer has moved on from the engineering and consultancy firm to focus his expertise into his current roles as director of EcoShape and founder of Adaelta.

Each year, IADC gives a safety award to one exceptional innovation which proves it is the best in its class. This year, 14 innovations addressing challenges faced within the dredging industry have been nominated.

CEDA’s Working Group on Beneficial Use aims to inspire sediment stakeholders and practitioners by describing the importance of sediments in the context of sustainable development and sharing a curated selection of case studies.

Following the Building with Nature concept, a pilot study was conducted introducing finegrained dredged sediments as a semicontinuous source of mud into a shallow tidal channel, naturally dispersing sediment to nearby mudflats and salt marshes.

Crews routinely perform vessel to vessel transfers, ensuring a project continues seamlessly. But the operation is not risk free. A roundtable of IADC members shared ideas on how to improve procedures to make crew transfers safer.

‘What will “sustainability” be in ten years? Our industry needs to be prepared for that.’ Luc Vandenbulcke kicked off 2019 in his new role as CEO of DEME Group. After 21 years working within the group, with 14 of those years starting up, leading and growing the group’s offshore subsidiary, he is now heading the company’s future as it navigates the evolving processes of sustainability.

The head of a dredge pump is an important performance parameter and a strongly fluctuating head may affect the operating stability of the pump unit. The IADC Young Author’s Award paper analyses unsteady characteristics of pump performance to improve control of the dredge pump.

In collaboration with the Natuurmonumenten (the Dutch Society for the Preservation of Nature), Boskalis constructed the Marker Wadden. The archipelago situated within the Markermeer enables processes which revitalise the natural ecology.

Popular instruments in the field, optical backscatter instruments (OBS) are used to measure suspended sediments. The sensitivity of OBS measurements in relation to grain size and the applicability of OBS measurements in mixed sediment environments is analysed.

Ecologist Patrick Meire has been researching the Scheldt for decades in the hope of implementing solutions which undo the damage caused by humans, industry and natural processes.

To connect Scandinavia with Germany, the world’s longest immersed tunnel will be built. The Fehmarnbelt will close a major gap in the European transport network while fostering the development of new nature and recreational landscapes.