WP4 Deliverables

Task 4.1 Pilot on intertidal habitat creation in the Tees (Tees River Trust, UK)

The IMMERSE project in the Tees estuary aims to create habitat along a stretch of the river which has been heavily modified using structures which will hold back sediments and form mud flats. Woody materials such as brash bundles made from Birch and Alder tree branches, coir rolls and rock rolls have been used to retain the sediment. The pilot site is located in an industrial area on a section of the river where large ships still operate. There are old jetties either side of the site which are no longer in use but offer excellent habitat. The work was carried out by members of staff from the Tees Rivers Trust over the course of several months in windows of opportunity when low tides allowed safe access to the site.

TRT report: Tees estuary habitat creation

Discover this solution interactively in the Tees StoryMaps.

Task 4.2 Assess adapted sediment management through use of numerical modelling
(Federal Waterways Engineering and Research Institute, Germany)

An existing numerical model for the Elbe estuary was optimised and applied in assessing the adapted sediment management in the estuary. The output of this task consists of two reports addressing adaptive sediment management and largescale river engineering measures that positively influence the tidal dynamics. The hydrodynamic effect of reconnecting the cut-off anabranch Dove Elbe on the Elbe estuary is presented, including recommendations to apply the model in other estuaries.

BAW Report: Impact of the creation of flood space in the area of the Tidal Elbe, Reconnection Dove Elbe: Results of the hydraulic engineering system study on the Dove Elbe measure (in German)

BAW Report: Assess adapted sediment management in the Elbe through use of new numerical model

Discover this solution interactively in the Elbe StoryMaps.

Task 4.3Assess existing pilot on stabilisation/ solidification of dredged masses and develop method for recovery of metals and polluted sediments in the GötaAlv 
(Chalmers University of Technology, Sweden) 

The aim of this project was to develop innovative, sustainable, and effective treatment techniques for organotin (TBT, DBT, and MBT) and metal contaminated sediment which also enables metalrecovery. Additionally, the aim was to investigate how sediment could be managed, and if treatedsediment could serve as a construction material 

Several techniques to remove TBT and metal from sediment were developed and tested in laboratory studies, including chemical oxidation by electrolysis and Fenton’s reagent, leaching with ultra-pure water, EDDS, saponified tall oil, iron colloids, humic acid, hydroxypropyl cellulose, and acid and alkaline solutions. 

Environmental impacts and costs associated with different sediment management strategies were studied using life cycle assessment and integrated monetary and environmental multicriteria analysis. Metal recovery from sediment was identified as a potential future alternative, with increasing metal prices and economic incentives as highly contaminated sediments cost more to handle. 

The results of these laboratory experiments and studies are published in several scientific papers (links provided in the report). 

Discover this solution interactively in the GötaälvStoryMaps. 

Task 4.4 Feasibility study on river engineering measure in the Elbe
(Hamburg Port Authority, Germany)

River engineering solutions that create additional flood space area known to affect sediment transport patterns and the development of specific habitats in estuaries such as shallow water areas. As part of a stakeholder consultation process 23 potential locations were identified for various engineering measures that could positively influence the characteristics of the Elbe estuary. They were discussed among the members of the estuary partnership “Forum Tideelbe”, and the 3 most suitable measures have been identified for further recommendation to the responsible authorities. The reconnection of the Dove Elbe, an anabranch located in the east of the city of Hamburg that has been separated from the estuary, was one of the most suitable locations to address tidal pumping but also to provide benefits for nature and society. IMMERSE partners HPA and BAW decided to support the estuary partnership by:

a) developing a measure layout to reconnect the Dove Elbe with the participation of stakeholders,

b) assessing the hydromorphological effects of the developed measure layout through numerical modelling, and

c) tendering a feasibility study that should investigate the ecological effects of the measure as well as the possible support of the measure by the locals by conducting stakeholder interviews.

Results of the investigation can be found in the (German) report: the study delivered important insights of the measure´s effects and led to concrete results, different than preliminary investigations in the estuary where only potential benefits were evaluated without considering social components. The whole process let to important insights on the relevance of stakeholder participation and adequate communication to achieve acceptance. Now, potential implementation is in the power of administrative decision-makers in the Elbe estuary.

Executive summary and lessons learned from a feasibility study: Effects of the reconnection of the Dove Elbe to the tidal Elbe and local stakeholders (English)

Report: Feasibility study on river engineering measure in the Elbe (in German)

Discover this solution interactively in the Elbe StoryMaps.

Task 4.5 Testlab: proof of concept tests for short-listed measures in the Humber 
(University of Hull, UK) 

This activity builds on activity 3.5 - Design measures for flood risk management while maintaining/enhancing environmental protection measures in the Humber, which aimed to assess the flood risk benefits of a series of conceptual flood protection measures for the Humber. Following that activity, five potential measures have been short-listed for further exploration within the present report. 

This report adopts a numerical modelling methodology to assess the short-listed flood alleviation measures for the Humber in terms of their flood risk benefits. This discussion performs a multi-criteria analysisin order toidentify which of the selected measures ranks highest. The analysis includes physical (i.e., maximum stages and flood volumes), economic (people and businesses affected, expected damages and GVA losses) and financial (construction costs) impacts effects of the modelled scenarios.  

Discover this solution interactively in the Humber StoryMaps. 

Additionally, a study on the potential ecological changesof the studied flood protection measures from predicted climate change and sea level rise scenarios are studied. The study semi-quantitatively and qualitatively in high level terms, indicates the changes to these features following the modelled scenarios and the repercussions of retaining or removing the upper shore defences. This includes whether there will be coastal squeeze following sea-level rise or whether the intertidal and wetland areas are allowed to migrate inland.  

The report focusses on the carrying capacity of the intertidal areas and discusses the relative loss and gain of that capacity, even to the extent that a loss of bird-feeding habitat could be a gain for the fishes. The report also discusses briefly the likely effects of water quality and permanent physical barriers on the status of the estuary. 

This publication is available upon request to r.e.thomas@hull.ac.uk.

Task 4.6 Pilot on cross-border solutions for maintenance dredging in the Scheldt
(Flemish Department of Mobility and Public Works, Belgium)

Currently sediment is being dredged in the Scheldt estuary to maintain the depth of the fairway, ensuring accessibility to the ports. In the Flemish Sea Scheldt the dredged sandy material is relocated to sites within the Sea Scheldt. However, to uphold the capacity of one of the relocation sites, commercial sand extraction is required. Extracting sediment out of the system is not favourable for the sediment balance in the estuary and creates hydro-morphological changes to the system, increasing the tidal range and causing tidal amplification. The cross-border sediment relocation pilot investigates the potential to relocate dredged sandy material from maintenance dredging just across the border to the Dutch Western Scheldt. The goal of this measure is to help maintain the sediment balance in the Scheldt estuary by limiting the need for sand extraction.

This note aims to report on the findings and achievements of the pilot, it covers the different phases towards executing the pilot, lessons learned and next steps towards implementation.

Read full report

Discover this solution interactively in Scheldt StoryMaps.

Task 4.7 Develop innovative rain gardens to filter and degrade microplastics 
(Chalmers University of Technology, Sweden) 

The aim and scientific challenge of this project was to design, construct and explore an innovative and sustainable rain garden with bioretention filters where microplastics and other pollutants from urban runoff are retained, degraded or recovered. The overarching goal was to significantly reduce the transport of urban pollution to receiving waters, to contribute to a green infrastructure and to a circular economy in the society. 

The first part of the project includes the design and start of the raingarden pilots and the initial results of the removal effectiveness and hydrologic performance. This pilot is continued after the IMMERSE project. 

Discover this solution interactively in the GötaälvStoryMaps. 

Task 4.8 Quantify the potential to use biological agents to filter microplastics from the water column within the Humber
(University of Hull, UK) 

The aim of this pilotwas to examine the controls of microplastic capture and retention by key benthic microbial biofilms and benthic invertebrates and explore thepotential for these interactions to be exploited as a mechanism to remove microplastics from the water column. 

Benthic biofilms and benthic invertebrates have the potential to influence the transport and fate of microplastics in estuaries but their use as a biological agent to remove microplastics may not yet be feasible. Nonetheless, these benthic organisms are transient sinks; capturing, trapping and redistributing microplastics as they are transported through estuaries. Further studies on the fate of microplastic particles that have interact with sediments, biofilms and sediment dwelling organisms are crucial and a vital step towards managing microplastics pollution in estuarine environments, as these studies have demonstrated that these interactions particle behaviour, movement and fate.  

Discover this solution interactively in the Humber StoryMaps.