PhD position Understanding and Predicting Suspended Sediment Dynamics in Estuaries

Human interventions and climate change are exerting increasing pressure on estuarine systems, profoundly altering their dynamics and often leading to negative consequences such as reduced flood safety, ecosystem degradation, and declining water quality. Given the growing challenges faced by these environments, there is an urgent need to improve our understanding of the physical, ecological, and biogeochemical processes that govern their behaviour.

The PhD candidate will develop and analyse new process-based mathematical models to improve our understanding and predictive capability of sediment dynamics in hyperturbid estuaries. These systems are characterized by extremely high suspended sediment concentrations, strong interactions between flow and sediment transport, and the formation of fluid mud layers, making them among the most challenging coastal environments to model.

The research will focus on the fundamental question of how hydrodynamics, turbulence, sediment transport, and sediment trapping interact under highly turbid conditions. Existing idealized estuarine models do not adequately capture these feedback mechanisms, particularly when sediment concentrations become sufficiently high to influence turbulence and, consequently, the flow itself. The PhD candidate will therefore extend an existing two-dimensional vertical (2DV) estuarine model by developing and implementing novel turbulence closures that explicitly account for the mutual interactions between turbulence and sediment dynamics.

Using a combination of analytical techniques, asymptotic methods, and numerical simulations, the candidate will investigate the emergence of turbidity maxima, the formation of fluid mud layers, and the mechanisms governing sediment retention in estuaries. Particular attention will be paid to identifying the dominant physical processes and determining how system behaviour changes under varying forcing conditions and parameter regimes. Model results will be evaluated against observations from several European estuaries, thereby linking fundamental theory to real-world applications.

In the second phase of the project, the research will advance beyond the traditional 2DV framework by incorporating lateral variability. This will result in a more comprehensive description of estuarine dynamics and enable the investigation of questions that cannot be addressed with width-averaged models. Specifically, the candidate will quantify the role of lateral circulation, channel-shoal interactions, and cross-estuary sediment transport in controlling the location and strength of estuarine turbidity maxima and the occurrence of fluid mud.

The project combines mathematical model development, nonlinear dynamical systems analysis, turbulence modelling, and environmental fluid mechanics. The successful candidate will contribute to the development of new theoretical understanding of sediment-rich estuarine systems and will collaborate closely with other PhD candidates and postdoctoral researchers within the iMose project. Strong interactions with knowledge institutes, including Deltares, will ensure that the research remains connected to contemporary scientific and societal challenges related to estuarine management and climate adaptation.

A Master's degree in (Applied) Mathematics, Applied Physics, or a related discipline is required. Candidates should have demonstrated expertise in the development of mathematical models for geophysical flows and turbulence, employing both analytical and numerical techniques.

We seek a researcher with a critical and inquisitive mindset, capable of rigorously evaluating results and translating findings into new and relevant research questions. The ability to work effectively both independently and as part of a multidisciplinary team is essential.

Strong communication skills are required, including fluency in English, both written and spoken. A willingness to learn the Dutch language is expected.

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