Dunes reveal fundamental concepts in Earth-surface dynamics Seminar

Dunes are fascinating bedforms that develop in air as well as under water. Bed form research is relevant to society, but also neatly illustrates a range of fundamental challenges that need to be overcome in the study of earth surface dynamics. Two such general aspects will feature in this presentation.
Firstly, bedform identification highlights the limits of classifications as a (subjective) methodology. It is unlikely that bedforms can be completely linked to their deposit – because geometry is defined at a single point in time while composition is the product of historical development.

Secondly, dune studies highlight the importance of time-space definitions. Time-space limits and resolution determine the size of dune populations and the variability in the boundary conditions of the formative flow. Long-term deposition by passage of many dunes in the thalweg differs dramatically from immediate deposition in areas of flow expansion. Thus, time-space choices underpin approaches to bedform preservation and the completeness of the sedimentary record. Large dune populations adapt to changing flow in a more ‘averaged’ manner, such that different dune hysteresis studies are difficult to compare. Therefore, time-space choices also underpin our understanding of the interaction between floods and developing subaqueous dunes that actively drive up water levels.