MUSA, Research into the behavior of mud-sand mixtures
Tidal basins and estuaries form an important transition zone between land and sea. These areas are vital for flora and fauna, but are also extensively used by humans, for example for shipping. For ecological and navigational purposes, it is important to understand how channels and shoals behave and what seabed compositions can be expected in different locations. The seabed in tidal basins and estuaries consists mainly of sand, silt and clay (jointly known as ‘mud’). The channels are often sandy, whilst the intertidal zones are rich in mud. The interaction between sand and mud, combined with currents and waves, leads to a complex dynamic of migrating channels and banks in these areas. To better understand the dynamics of MUd-SAnd mixtures, field measurements and flume tests have been carried out.
- Client: TKI Project, The consortium consists of WaterProof, Leo van Rijn Sediment Consultancy (LVRS), Deltares, Jan De Nul, DEME, Boskalis, HR Wallingford, DHI, Rijkswaterstaat, MOW Vlaanderen, Svasek and Nortek.
- Location: Wadden Sea, Western Scheldt, Scheldt River
Much is already known about the behaviour of sand and mud individually, and various models and tools are available to predict sedimentation and sediment transport. However, there is still little knowledge regarding sand-mud mixtures, and only a limited number of verified models are available due to a lack of high-quality field observations. Furthermore, to date, no single model or tool has managed to incorporate both the settling velocity, erosion processes and the shear stress on the seabed caused by waves and currents for sand-mud mixtures. Consequently, so far, different models have been used for the mud fraction and for the sand fraction. As a result, predictions from such models do not always correspond well with reality, because they concern sand-mud mixtures, which behave differently from mud and sand separately.
The importance of field data
In order to better understand the morphological impact of further deepening an existing channel or constructing a harbour, or to calculate the dredging volumes required to maintain a navigation channel, better models for sand-mud mixtures are needed. To develop and improve these models, high-quality field data is required. After all, it is in the field that one can best observe what is actually happening and which processes are most significant.
For the MUSA project, a collaboration between WaterProof and a number of leading research institutes, WaterProof has carried out laboratory experiments and several field campaigns in the Wadden Sea and the Western Scheldt. During the field measurements, the flow velocity and sand and mud concentrations were measured at various depths above the seabed. The seabed samples were tested in the laboratory for wet and dry density, sand/mud fraction, grain size distribution and settling velocity. A large number of sediment samples were further tested in WaterProof’s various flumes. Experiments were carried out involving flow, waves, and a combination of waves and flow, and for various sediment compositions of the seabed.
Improved models
The data collected during the field campaigns and laboratory experiments has been analysed and applied in various engineering tools and numerical models. The MUSA project was launched in 2024 and will run until mid-2028. To date, the project has led to the improvement of various relations used in computer models for predicting morphological processes in areas where sand-mud mixtures are common.
Take a look at our other projects
Sediment transport pathways along the south-east coast of Florida
The US state of Florida has over 2,000 km of coastline, featuring a mix of beautiful beaches and coral reefs. The south-east coast borders a wide strait, the Florida Strait, through which a strong current of warm water flows northwards. Further north, this Florida Current feeds into the Gulf Stream, which ultimately brings us the temperate climate of western Europe. Along the south-east coast, the coastline is indented by several sea inlets and access channels leading to harbours.
MUSA, Research into the behavior of mud-sand mixtures
MUSA, Research into the behavior of silt-sand mixtures Tidal basins and estuaries form an important transition zone between land and sea. These areas are vital for flora and fauna, but are also extensively used by humans, for example for shipping. For ecological and navigational purposes, it is important to understand how channels and shoals behave and what seabed compositions can be expected in different locations. The seabed in tidal basins and estuaries consists mainly of sand and silt. The channels are often sandy, whilst the intertidal zones are rich in silt. The interaction between sand and silt, combined with currents and waves, leads to a complex dynamic of migrating channels and banks in these areas.
Long-Term EMF Measurements
Around buried export cables connecting offshore wind farms to the mainland, electromagnetic fields (EMF) are generated by the electrical current flowing through the cables. These EMF may potentially affect marine life. The magnitude of these fields and their potential impact are largely unknown. To gain a better understanding of these fields, we developed an autonomous EMF measurement station capable of continuously measuring EMF with nanotesla-level accuracy.
