The MUSAII project should further develop the knowledge and tools for quantitative assessments of sand-mud dynamics in sediment management strategies and engineering projects. Governmental agencies that are responsible for the management of estuaries and tidal basins (e.g., Rijkswaterstaat and MOW Vlaanderen) benefit from better predictions and sound evaluations by research institutes (e.g., Deltares, WL Borgerhout (part of MOW Vlaanderen)) and consultants (e.g., WaterProof, DHI and Svašek). Dredging contractors (e.g., Jan de Nul, Boskalis and DEME) reduce the amount of uncertainty in their projects by having the right knowledge and tools for quantitative estimates available at an early stage in the project.

Research on the topics mentioned in the previous section will provide the needed knowledge and tools on sand-mud dynamics. The following research questions have been formulated to address the knowledge development for the first three topics of MUSAII:

• How does the resuspension of sediment samples that are (freshly) deposited on the seabed vary as a function of their bulk density?
• How is the resuspension process of the sediment affected by its consolidation over tidal timescales?
• How does the erosion rate of a seabed or estuarine bed depend on the mud content and other geotechnical properties (e.g., porosity, permeability)?
• How does the slope of a mud-sand bed (e.g., at mounds or bunds) affect the erosional behaviour?

The fundamental knowledge gained can be applied to develop practical tools and numerical models that are used by contractors, engineering firms and knowledge institutes.

Measurement techniques need to be improved for both the knowledge development within this project and the field monitoring carried out by several consortium partners. Within this project, high quality field data of settling velocities, near-bed sediment transport rates and in-situ bulk densities will advance the understanding on sand-mud dynamics and the underlying physics. The optimized measurement techniques will benefit the consortium in general by reducing the uncertainty in impact assessments (relevant for e.g., engineering projects) and the evaluation of sediment management strategies (relevant for e.g., maintenance dredging of navigation channels).

[KIA-MMIP 6A]:
In the MUSAII project physical system knowledge is developed on the behaviour of sand-mud mixtures. This fundamental research is then applied in practical tools and numerical models, which are tested for at least one case study.

The working field of MUSAII consists of estuaries, tidal basins and harbours. They contain important habitats for flora and fauna and are extensively used by people (navigation, fisheries). For ecological and navigational purposes, it is important to understand and predict the evolution of channels and shoals, including sedimentation rates and the composition of the bed sediments. The bed material of large estuaries and tidal basins largely consists of mixtures of mud and sand, with predominantly sandy channels and mainly muddy intertidal areas.

The developed tools, numerical models, monitoring methods and database will aid sediment management strategies and engineering projects (e.g., maintenance dredging in channels and ports and related plume dispersion) and predictive studies.

In summary, the MUSAII project will contribute to MMIP 6A “Duurzame maatregelen voor veilige, weerbare, bevaarbare delta’s” with fundamental knowledge on bed development which contributes to more sustainable sediment management strategies and navigability of estuaries, tidal basins and harbours.

[KIA-MMIP 6B]:
The MUSAII project contributes to knowledge on the development of sand-mud mixtures, found in estuaries, tidal basins and harbours. This fundamental knowledge developed in MUSAII contributes to more sustainable sediment management, such as reducing dredging requirements and through more efficient dredging strategies.

Therefore MUSAII contributes 5ot he MMIP 6B “Verminderen gebruik primaire (bouw)grondstoffen”.

1 - Collection of sediment samples in the field and characterization of samples in the laboratory
09/24 - 12/24
Industrieel onderzoek
Collection of sediment samples from various field sites, and characterization of samples (e.g., particle size distribution and wet- and dry bulk density) in the laboratory of WaterProof.

Samples will be collected by WaterProof, Rijkswaterstaat, MOW Vlaanderen, Jan de Nul, DEME and Boskalis.
Characterization of the samples will be executed by WaterProof, MOW Vlaanderen – WLB and Deltares.

2 - Short-bed flume tests on resuspension behavior
10/24 - 03/25
Industrieel onderzoek
Short-bed flume tests with field/artificially-mixed sediment samples on resuspension behavior of sand but especially mud, where we test the effect of:
- the bulk density and
- consolidation on tidal timescales (i.e., hours to days)
on the resistance against erosion.

Flume tests will be carried out in the laboratory of WaterProof, in collaboration with Leo van Rijn and Deltares and by using instruments from other consortium partners. Several consortium partners participate in carrying out the flume experiments via their in-kind contribution.

3 - Longer-bed flume tests to quantify erosion rates
03/25 - 08/25
Industrieel onderzoek
Longer-bed flume tests with field/artificially-mixed samples with currents and waves to quantify erosion rates and the variability with the mud content and other geotechnical properties, such as the porosity and the permeability of the sediment bed. Focus herein will be on the influence of mud on sand erosion for a range of hydraulic conditions.
A set of longer-bed flume experiments with sloping beds and trenches will be carried out to simulate the erosion of bunds and the deposition of sand-mud mixtures in channels.

Flume tests will be carried out in the laboratory of WaterProof, in collaboration with Leo van Rijn and Deltares and by using instruments from other consortium partners. Several consortium partners participate in carrying out the flume experiments via their in-kind contribution.

4 - Field and laboratory measurements of settling velocities
08/25 - 12/25
Industrieel onderzoek
Field and laboratory measurements of settling velocity with various instruments:
− application of Piranha, LABSFLOC2, LISST, laser diffraction-method and possibly other instruments that are available within the consortium in laboratory settings and field conditions
− evaluation of measurement devices for quantifying settling velocities in engineering applications.

Test are carried out by Leo van Rijn and WaterProof, in collaboration with Deltares, DHI and other partners.

5a - Field measurements of (near-bed) sediment concentrations and transport rates – Wadden Sea
08/25 - 06/26
Industrieel onderzoek
Optimization of the measurement methodology for sediment concentrations and transport rates of sand and mud and collection of field data by using a set of instruments:
− Acoustic instruments (ADV and (multi-frequency) ADCP);
− Optical instruments (OBS and LISST);
− Sampling of sediment-water mixtures.
The location of the field measurements in the Wadden Sea is coordinated with ongoing field monitoring by Rijkswaterstaat; most likely, the study site will be chosen close to the Boontjes (navigation channel between Harlingen and Kornwerderzand).

Measurement campaign (and processing of data) by WaterProof, in collaboration with Leo van Rijn, Deltares, Nortek, Rijkswaterstaat and MOW Vlaanderen – WLB.

5b - Field measurements of (near-bed) sediment concentrations and transport rates – Western Scheldt
08/25 - 06/26
Industrieel onderzoek
Optimization of the measurement methodology for (near-bed) sediment concentrations and transport rates of sand and mud and collection of field data by using a set of instruments:
− Acoustic instruments (ADV and (multi-frequency) ADCP);
− Optical instruments (OBS and LISST);
− Sampling of sediment-water mixtures.
The location of the field measurements in the Scheldt Estuary is coordinated with ongoing projects and related field monitoring by Rijkswaterstaat and MOW Vlaanderen; most likely, the study site will be chosen at the Dutch-Belgian border in the Scheldt Estuary.

Measurement campaign (and processing of data) by MOW Vlaanderen, in collaboration with Deltares, Rijkswaterstaat, WaterProof, Leo van Rijn and Nortek.

6 - Instrumentation bulk-density measurements
08/25 - 12/25
Experimenteel onderzoek
Comparison between various existing instruments for measuring bulk-density in the field and/or lab (densi-probe, ADMODUS, etc), such that the performance of these instruments can be evaluated by comparing the measurement results.

The instruments are provided by the partners involved: WaterProof, Deltares, Rijkswaterstaat, DHI.

7 - Analysis and formulations
10/24 - 08/27
Industrieel onderzoek
Analysis of data from laboratory experiments and field measurements, to validate and improve process formulations for sand-mud dynamics

Analyses will be carried out by Deltares and Leo van Rijn, with support from other consortium partners.

8 - Engineering tools
04/26 - 04/27
Industrieel onderzoek
Improvement of engineering tools to estimate suspended sediment concentrations, channel siltation and sand-mud transport:
- SEDPAR for sediment parameters;
- SEDPIT for sedimentation of shipping channels;
- SEDHAR for sedimentation of harbour basins;
- SEDCON for concentrations and transport of mud, silt and sand; and
- TMUD for the computation of mud transport over a tidal cycle).

To this end, the newly gathered data from the flume experiments and field measurements will be used. Furthermore, new engineering tools will be developed and tested:
- SEDPLUME for the modelling of the dispersion of fines; and
- BEDCONSOL for the modelling of the consolidation of mud-sand beds.
- SUSTIM2DV-model to compute erosion and sedimentation in (dredged) channels and on nearshore mounds.

Development and improvement of engineering tools by Leo van Rijn, with support from Deltares and WaterProof. Testing and application in case study in collaboration with Jan de Nul, DEME and Boskalis.

9 - Numerical modelling
04/26 - 04/27
Industrieel onderzoek
Implementation and testing of improved formulations for sand-mud mixtures in process-based modelling software packages Delft3D, MIKE and FINEL, and application in case studies. Several case studies will be connected to the field sites in the Wadden Sea and/or Scheldt Estuary, such that field measurements are used to calibrate/validate the models.

Implementation by Deltares, DHI and Svašek. Testing and application in case studies also by MOW Vlaanderen.

MUSAII builds upon the results of the TKI-MUSA project (2020-2024), in which many laboratory experiments and field measurements were carried out and a set of modelling software and engineering tools was improved. Status updates and deliverables of the MUSA project can be found online: https://publicwiki.deltares.nl/display/TKIP/DEL112+-+MUSA.
The focus in MUSAII is on topics identified in the TKI-MUSA project to require further investigation. The link between these topics listed in Section 3.2 and the results obtained in the TKI-MUSA project are specified below:
• We found a strong relation between the dry bulk density of sand-mud mixtures and their resistance against erosion in flume experiments. This relation requires validation for sediment samples that are freshly deposited. In addition, in-situ measurements of dry bulk densities are still not straightforward;
• A small set of long-bed flume experiments suggests that lower erosion rates for increasing mud content in the bed were caused by a change in the erodibility parameter rather than an increased critical bed shear stress for erosion (as commonly assumed). As the number of long-bed experiments was limited, hence rendering the significance of this finding unanswered, a systematic investigation of the erosion rates of sand-mud beds is part of the flume experiments in MUSAII;
• After a set of flume experiments with erosion of a flat sediment bed in the TKI-MUSA project, the effects of a sloping sediment bed on the erosion and the deposition in a transverse channel will be investigated;
• A wide range of instruments has been used for field measurements of sand-mud dynamics. However, the range of uncertainty in the measurements of e.g., sediment transport rates and settling velocities is large and different instruments may provide different results. A close comparison between the measurement principles and the measurement results of a set of instruments is therefore part of MUSAII.

1
Global database with sediment characteristics
Application by contractors (Jan de Nul, DEME, Boskalis, Van Oord)
When used regularly.
Deltares/WaterProof

2
Report and dataset on the set-up and results of the short-bed flume experiments
Application of information described in report.
Results described in reports are supported by all partners.
WaterProof/Leo van Rijn

3
Report and dataset on the set-up and results of the longer-bed flume experiments
Application of information described in report.
Results described in reports are supported by all partners.
WaterProof/Leo van Rijn

4
Report and dataset: Improved method and instrumentation for measurements of settling velocities,
Application of methods/instruments in settling studies.
Regular use with new information on accuracy in successive projects.
Leo van Rijn/WaterProof

5
Report and dataset: Improved method (and instrumentation) for in-situ measurements of bulk densities
Application of methods/instruments for sediment characterization.
Regular use with new information in successive projects.
WaterProof

6
Report and dataset: Improved method for field measurements of concentrations and transport rates of sand and mud; application in the Wadden Sea
Application of methods/instruments in field studies.
Regular use with new information in successive projects.
WaterProof

7
Report and dataset: Improved method for field measurements of concentrations and transport rates of sand and mud: application in the Scheldt Estuary
Application of methods/instruments in field studies.
Regular use with new information in successive projects.
MOW Vlaanderen

8
Report: Analysis of laboratory experiments and field measurements and improvements to existing sediment transport formulations
Application of information described in report.
Results described in reports are supported by all partners.
Leo van Rijn/Deltares

9
Engineering tools (software and related documentation, including the description of case-studies)
Testing in case study.
Tools are used regularly in successive projects.
Leo van Rijn

10
Numerical modelling (software; model schematizations and documentation, including the description of case-studies)
Testing in case study.
Models are used regularly in successive projects.
Deltares, DHI, Svašek

1: Global database
Consortium
The database that is going to be set up in this Project, with data and parameters from the literature analysis, the laboratory experiments and the field measurements, will be made publicly available (i.e., open access). Data generated outside of this Project will only be included in this database if explicit permission has been granted by the Partner who shared the data. If needed, data can be included in the database without explicit references to the source, i.e., anonymized.

4: Methods/instruments settling velocities
N/A
The data obtained by field measurements that will be carried out by WaterProof as part of this TKI Project will be made publicly available as soon as the results are published, and no later than one year after the end of this TKI Project (i.e., no later than 31 September 2028). Existing data or new data that is provided by the Project Partners for analysis, but which is collected outside of this TKI Project, does not have to be made available publicly or can be processed anonymously.
The Project Partners will agree on the method for anonymization and publication prior to the analysis of the data.

5: Methods/instruments in-situ bulk density
N/A

6, 7: Methods/instruments near-bed sand-mud suspensions/transports
N/A

6, 7: Report field experiments
Authors
All reports will be made will be made publicly available on the Deltares Publicwiki as soon as the results are published, and no later than one year after the end of this TKI Project (i.e., no later than 31 September 2028).

2,3: Report lab experiments
Authors
All reports will be made will be made publicly available on the Deltares Publicwiki as soon as the results are published, and no later than one year after the end of this TKI Project (i.e., no later than 31 September 2028).

8: Report analysis with improved transport formulas
Authors
All reports will be made will be made publicly available on the Deltares Publicwiki as soon as the results are published, and no later than one year after the end of this TKI Project (i.e., no later than 31 September 2028).

9: Improved practical tools
Leo van Rijn
• Each Partner keeps the right for copyright on his own creations made during the Project.
• During the Project, which ends on September 1 2027 or on a mutually agreed date (i.e., agreed by all Partners), every Partner will actively share additions and modifications made to the practical engineering tools with the other Partners.
• Every Partner has the everlasting right to use, copy and modify all practical engineering tools that were created as part of this Project.
• For other cases, the usual conditions and disclaimers for the use of practical engineering tools apply. These conditions and disclaimers are adjusted occasionally.
After ending the Project, the following conditions apply:
a) Partners distribute practical engineering tools under the LGPL1;
b) Partners may distribute the practical engineering tools to third parties subject to the following conditions:
1. practical engineering tools are completely or partially the result of Deltares’ activities within the Project are shared free of charge with third parties no later than 12 weeks after the end of the financial year in which the activities in the Project have been completed;
2. practical engineering tools that are exclusively the result of the activities of the other Partners in the Project must be shared free of charge with third parties no later than 12 weeks after the end of the financial year in which the activities in the Project are completed. User rights are as defined by the LGPL. In an earlier stage of the Project each of these other Partners is allowed to provide practical engineering tools that are exclusively the result of the Partners’ own activities in the Project to self-chosen third parties or consortium Partners.

10: Improved numerical models – Delft3D
Deltares
The Delft3D software is open-source software (GNU AGPL). The software provides direct access to state-of-the-art process knowledge (http://oss.delft3d.nl, open source with >24000 developers and users in >140 countries, >8000 publications).The improvements resulting from this TKI Project will be fed back into the open-source community. The compiled versions of the software will initially be shared with the Partners in this TKI Project as alpha releases for testing, validation and documentation.
One of the end results of this TKI Project is a compiled release of Delft3D, which is approved by the Partners in this TKI Project, together with the source code, test model(s) and documentation. The compiled release of Delft3D will also be tested on the latest available version of the Delft3D test bench. This provides insight into the impact of improvements on the entire field of application of Delft3D.

10: Improved numerical models – MIKE
DHI
The MIKE powered by DHI software is a commercially available software suite for water engineering professionals, providing state-of-the-art process descriptions within the field of physical modelling of water environments for more than 30 years.
The improvements resulting from this TKI project will be fed back into our product development roadmap for DHI’s integrated Mud Transport Process Module for our Flexible Mesh modelling products. One of the end results of this TKI project is a compiled release of the MIKE powered by DHI suite, featuring an enhanced Mud Transport module along with test model cases, user guides and documentation.
10: Improved numerical models - FINEL
Svašek
FINEL is frequently used in consultancy studies in the Netherlands (Western Scheldt) and worldwide where mud-sand interaction is important. Implementation in FINEL will result in the testing of the improved formulations for sand-mud mixtures. Implementation and testing will lead to an enhanced sand-mud transport module in FINEL, together with documentation and a description of the case study/studies and the findings.

A description of the project, partners, planning, status updates and deliverables will be posted on the Deltares Publicwiki. A selection of findings is envisaged to be published as scientific papers.

Het consortium zal z.s.m. een samenwerkingsovereenkomst sluiten. Het project wordt niet aan RvO voorgelegd / of wordt gestart zonder een dergelijke overeenkomst.