Baltic TRANSCOAST Seminar - Dr. Alice Lefebvre (MARUM)

Underwater dunes are found in various environments with strong
hydrodynamics and sandy sediment such as rivers, estuaries and
continental shelves. They both reflect and influence hydrodynamic and
sediment dynamics processes at various spatiotemporal scales. Therefore,
a good understanding and precise characterisation of bedform dynamics
and their interaction with the overlying flow are necessary for the
modelling and prediction of large-scale hydro- and morphodynamics. The
study of their presence, size and movement is also directly relevant for
a wide range of applications such as the dynamics of mine burial, the
impact of marine aggregate extraction, the safety of marine renewable
energy structures, and the control of navigational depth.

During this talk, I will introduce underwater dunes and their relevance,
using concrete examples. I will then describe the influence of dunes on
the flow, with a focus on bedform roughness. Using a recent study of the
dunes in the Weser Estuary, I will further discuss the importance of
bedform morphology and the differences between river, estuarine and
marine dunes.