The aim of this work package is to analyse estuarine pressures to improve collective understanding of anticipated pressures and trends. Based on this knowledge solutions to tackle common estuarine pressures can be explored and further researched.
Task 3.1 Summary of status of current pressures and trends, and analysis of current measures effectiveness
(Coordinated by Port of Antwerp-Bruges, Belgium)
This report gives a state of knowledge overview of current pressures and trends occuring in North Sea Region estuaries with focus on the involved partner estuaries. This information forms the foundation for the development of measures and strategies. It should be kept in mind that not all common trends and pressures are addressed, only those of relevance to the development of solutions within IMMERSE.
This report includes 2 major parts:
• Overview of existing and anticipated/future pressures and trends, based on current research;
• Transferability of measures to IMMERSE estuaries.
Task 3.2 Develop a morphological management strategy in the Scheldt
(Port of Antwerp-Bruges, Belgium)
To strengthen the multiple channel system at the the zone of Hansweert-Bath, the Port of Antwerp-Bruges did a modelling study on a holistic morphological management strategy with a focus on the different challenges which put a pressure on the system such as sea level rise, safety against flooding, nautical accessibility and nature development.
At the zone of Hansweert-Bath a typical morphological evolution has taken place. The flood channel started to erode the outer bend. It becomes less deep and wider and tends to flow out more perpendicular to the “main channel”, potentially creating a nautical hindering cross-current in the main channel. In time this morphological evolution would continue, resulting in a flood channel which becomes more and more curved (erosion at outer bend, sedimentation in inner bend). After some years, this flood channel would become to curved for the flood flow, resulting in a new flood channel that will develop through the sandbar of Valkenisse. This is a process that occurs naturally over 10-20 years time. However this evolution would imply a temporarily negative condition for different functions of the estuary. The question is raised during this feasability study how can we accelerate this natural process to the situation of 10-20 years later.
The exploration was focussed on smart dredging and depositing materials in this zone, soft measures which will not create unwanted effects on the longer term. The effects were studied on hydromorphology, sediments, ecology, nautical accessibility and tidal range.
We gain high level insights on how to influence the hydromorphological processes in the Scheldt estuary and learned that more research is needed on the effect of the cross current perpendicular to the main channel, the effect of some hard structures (i.e. groynes) influencing the Zimmerman channel, the lessons that can be learned from historical developments of the bathymetry & autonomous developments and the impact of measures taken downstream of the side channel.
Report of a modelling study on sediment management in estuaries
Report with results of model simulations for a sediment management case in the Sea Scheldt
Report with results of model simulations for a sediment management case in the Western Scheldt (in Dutch)
Discover this solution interactively in Scheldt StoryMap.
Task 3.3 Design solutions for managing contaminated sediments in the Göta älv
(Chalmers University of Technology, Sweden)
Sediment needs to be regularly dredged and handled in the Göta älv (Göta River) estuary, in the same way as at many other sites worldwide. However, sediment often has elevated levels of contaminants, such as metals and organotin compounds as for example tributyltin (TBT), originating from different anthropogenic activities in and around the water. Organotin compounds have demonstrated negative environmental effects even at low concentrations and are of worldwide concern for sediment stakeholders. In sediments from Swedish waters, contents of TBT of up to 10 mg/kg have been measured, with the highest contents reported for the Göta älv. Although the use of TBT in boat paints has long been banned in the European Union, high levels are still found in marine and coastal sediments and remain a problem.
In this report, the sediment management practices in Göta älv are investigated and the findings are discussed in the context of applicability to other sites in the North Sea Region. Designed solutions for evaluating the sustainability of sediment management methods are presented and the views of an international group of sediment stakeholders on the current sediment management and presented designed solutions are presented.
Discover this solution interactively in Göta älv StoryMap.
Task 3.4 Co-location of mariculture with an inshore windfarm in the Tees
(Tees Rivers Trust, UK)
The Tees Estuary holds a lot of ecological and socio-economic importance, it supports many different uses from commercial fisheries, heavy industry to recreational activities. Teesport is situated on the estuary edge and is currently the third largest port in the UK. The Tees Estuary has historically had multiple water pollution issues derived from a diverse array of sources, including the industrial sector and the water industry. Often the need to address water quality issues is negated by the economic benefits of pollution creating industries and the cost of water quality improvement. In order to solve this problem, it is proposed that a mariculture development be created co-located inside the Teesside Offshore Wind Farm to provide an economic stimulus for water quality improvement.
This report provides an overview of the potential to create co-locate mariculture at this specific location with an evaluation of the environment for different species, designs and an economic and legislative assessment.
Discover this solution interactively in Tees StoryMap.
Task 3.5 Design measures for flood risk management while maintaining /enhancing environmental protection measures in the Humber
(University of Hull, UK)
The Humber estuary drains one fifth of England (24,472 km2), and provides the largest single input of freshwater to the North Sea from the English coastline. The wide, shallow, macrotidal estuary provides extensive wildlife habitat in its large intertidal zones and salt marshes and is thus of ecological importance for a number of habitats and species. The low-lying nature of the floodplains surrounding the Humber mean that the region is at severe risk of flooding during storm surges, which is expected to be exacerbated by forecast sea level rise.
Flood risk management in the Humber needs to be designed and implemented to provide cost effective, longer-term resilience to flooding without compromising ecosystems and causing damage to natural habitats along the estuary. A satisfactory solution requires co-development with estuary stakeholders. The University of Hull (UoH) has engaged with the Environment Agency, 12 local authorities and key stakeholders including Associated British Ports (ABP), Natural England and Internal Drainage Boards- to develop the Humber 2100+ flood risk strategy that aims to simultaneously address tidal flood risk while reinforcing the long-term ambition for a prosperous Humber, which is a safe and sustainable place to live, work and visit.
This report adopts a numerical modelling methodology to assess a range of conceptual flood alleviation measures for the Humber in terms of their flood risk benefits.
Discover this solution interactively in Humber StoryMap.
Task 3.6/3.7 Explore solutions as part of a sediment strategy to adapt to the effects of climate change and sea level rise in the Scheldt estuary
Rijkswaterstaat aims to construct a pilot nourishment in the mouth of the Scheldt Estuary in order to 1) increase the knowledge of nourishing ebb-tidal deltas, 2) develop knowledge of the nourishment effect on local hydrodynamics, morphodynamics and ecology and 3) to use this knowledge to improve large-scale numerical models to improve our capabilities to answer questions such as the impact of sea-level rise.
Multiple reports have been produced for the set-up of a pilot nourishment.
This report contains a general area description and an overview of relevant data that is available about the mouth of the Scheldt estuary.
In order to identify gaps in understanding and data, this report is an addition to the overview of the existing knowledge and available data on the morphology and the ecology of the mouth of the Scheldt Estuary that was already described in report .
- Pilot nourishment: assessment framework and alternative locations for the nourishment (in Dutch, with English summary)
This report describes the boundary conditions and evaluation framework for the pilot nourishment. These were derived from the nourishment objectives and the knowledge base of the mouth of the Scheldt estuary described in reports  and . Using this framework to asses 5 alternative nourishment locations, the area on the southern edge of the Vlakte van de Raan, north of the Wielingen tidal channel, turned out to be the preferential nourishment zone.
To make a decision about the exact location of the pilot nourishment, this report studies the sediment transport patterns in the mouth of the Scheldt estuary, making use of numerical modelling in Delft3D and SedTRAILS.
- Morphological development of the southern part of the Vlakte van de Raan, mouth of the Scheldt estuary (in Dutch, with English summary)
The area on the southern edge of the Vlakte van de Raan, north of the Wielingen tidal channel was identified as the preferential nourishment zone and this report aims to describe and explain the morphological development of this area.
- Pilot nourishment in the mouth of the Scheldt estuary: nourishment variants (in Dutch, with English summary)
The area on the southern edge of the Vlakte van de Raan, north of the Wielingen tidal channel was identified as the preferential nourishment zone. In this report 10 nourishments variants for this area are presented, discussed and assessed. These all have a total volume of 1,5 million m3 and consist of a combination of four different locations, two thicknesses (1 m and 2 m) and one or two nourishment elements.
To achieve objectives 1 and 2, the knowledge gaps and questions are translated into information requirements. The information requirements are divided in two themes, i.e. (1) hydrodynamics, morphology and sediment; and (2) ecology. For the ecology theme, the information requirements are also translated into a monitoring plan.
Discover this solution interactively in the Scheldt StoryMap.
Task 3.8/3.9 Improve understanding of contributing role of local waterways to flooding in Holbæk fjord & develop a coordinated local solution to address flooding
(Holbæk municipality, Denmark)
The coastal areas in Holbæk Municipality are referred to as fjord coasts, these coastal profiles are more protected than the coasts facing the open sea. On fjord coastal stretches, salt meadows can be formed, as is the case at several places in Holbæk Municipality. Flooding of these areas is natural for coastal ecosystems and the flora and fauna that grow and lives on the salt marshes. Floods occur naturally based on the conditions created by the dynamics between land and water. During the storm Bodil in 2013, several stretches along the fjord coasts were flooded, including a summer house area at Kisserup and several houses along Strandmøllevej in Holbæk city. The Danish coastal nature is an example of wild nature and free dynamics in the landscape. Climate change will cause more or less permanent flooding of the current completely coastal nature types, and thus the areas between the waterline and infrastructure and cultivated areas will slowly become smaller. It will also result in the disapearance of salt marshes in many places and creation of new habitat types. The coastal dynamics will as as a result of climate change become more frequent and violent, and on some coastal stretches will the floods thus result in material destruction as was the case during the storm Bodil.
This report gives the results of a geographical risk mapping carried out for the Holbæk area. Also key elements for developing flood defence solutions are discussed.
Discover this solution interactively in Danish Fjords StoryMap.
Task 3.10 Regional dynamic flood protection measure in the Roskildefjord and Isefjord
North Sea Region estuaries are valuable areas for habitats and ecosystems protected by European legislation, however, they are threatend by rising sea-levels and more intense storm-surges. Flood protection is on the political agenda both locally, regionally and on a national level in Denmark. However, flood defence systems on a regional level have not been systematically investigated and it is not straight forward due to the sensitivity of the areas.
Within this task, extensive numerical studies have been performed specifically for Isefjord and Roskilde Fjord in Denmark. The study uses numerical models to investigate the effects of measures in sensitive shallow tidal estuaries. Together with stakeholder integration and political commitment, this activity aimed at improving development and accelerate implementation of large-scale measures leading to better accessible and a more sustainable estuary.
More specifically this report focuses on:
- Overview of existing and anticipated/future pressures and trends;
- Analysis of flood protection measures to deliver identified benefits;
- To control risks of flooding and climate change while conserving sufficient ecosystems;
- Investigate transferability of the measures to other estuaries.
Discover this solution interactively in Danish Fjords StoryMap.
Task 3.11 State of knowledge of the effects and distribution of microplastics in estuarine environments and exploration of possible measures.
(Coordinated by University of Hull, UK)
Estuarine environments are a major sink for microplastics pollution, yet we do not fully understand microplastics entry points and pathways, their transport dynamics and how particles behaviour and fate can be affected by the physico-chemical environment and biological interactions as there are transported through estuaries.
This report discusses current knowledge on global microplastics spatial and temporal distributions and drivers for sediment, water and biotic compartments, and an overview of what is known from North Sea Region estuaries is presented. We discuss the potential for microplastics pollution to interact with other estuarine stressors such as climate related changes, and how future increases in storms and floods may further aggravate microplastics entry to estuaries. The potential risks and hazards of microplastics in estuaries are discussed from individual organisms through to ecosystem scale effects and potential mitigation strategies are presented.
This report also provides an overview of key knowledge gaps that need to be addressed to better understand microplastics pollution in estuarine systems, prevent their entry to these vulnerable systems and mitigate and manage estuarine microplastics now and into the future.