Idealized modeling of estuarine sand dunes

PhD research

April 2019 – November 2023

People involved
W.M. van der Sande, MSc (PhD candidate) 
Prof.dr. S.J.M.H. Hulscher (Promoter) P.C. Roos (Daily supervisor )

NWO Perspectief-programma: SALTISolutions
Van Oord

Summary of the research
Sand dunes are large-scale dynamic bedforms that occur in estuaries. They limit the depth of navigation channels and jeopardize other infrastructure (such as pipelines and electricity cables). Hence, they need to be monitored and dredged regularly. Furthermore, estuarine sand dunes are associated with significant hydraulic roughness, which makes them relevant to flood safety and salt intrusion. Various field studies have been performed to generate case-specific knowledge of these bedforms, but generic explanations of estuarine sand dune properties and dynamics are lacking.

This research aims to uncover natural and human-induced estuarine sand dune dynamics through an idealized process-based modeling approach. As ingredients for this model, we will include processes that have been identified as important driving factors of the dynamics of marine sand waves and river dunes. Furthermore, we will determine what estuarine-specific processes need to be included through a literature review.

With the model formulation at hand, we will perform a so-called linear stability analysis to reveal mechanisms that underlie formation and the properties of the dunes that initially grow fastest. An elaborate sensitivity analysis will show in what way the processes and parameters influence the formation mechanisms.

Subsequently, the solution to the aforementioned model formulation will be extended to the finite amplitude regime through nonlinear modeling. This will reveal the mechanisms that underlie growth towards a finite amplitude. Sensitivity analyses will show the dependence of dune properties and dynamics on input parameters and processes.

Regarding validation, the qualitative accuracy of the proposed model solutions (linear and nonlinear) will be verified through comparisons with data available from literature. Furthermore, the model will be used to assess the effect of human interventions on estuarine sand dune dynamics, which will be a first step to support a more sustainable management of estuaries.

Sand dunes
Idealized modeling