Modellierung der Dünenmorphodynamik unter Berücksichtigung multimodaler Windsysteme, der Vegetation und biogener Krusten

• Antragsteller: Dr. Eric Josef Ribeiro Parteli
• Fachliche Zuordnung: Statistische Physik, Nichtlineare Dynamik, Komplexe Systeme, Weiche und fluide Materie, Biologische Physik ; Physische Geographie
• Förderung: Förderung von 2015 bis 2022
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 280821821

• Erstellungsjahr: 2023

Zusammenfassung der Projektergebnisse

The goal of the project was the morphodynamic modelling of Aeolian (wind-blown) sand dunes with consideration of multimodal winds and biological sand stabilizers, including macrophytic vegetation and crusts. Our modelling paved the way toward the incorporation of Aeolian geomorphodynamics in Earth System simulations and contributed to elucidate long-standing open questions in Aeolian geomorphology. We have shown that the meandering of elongating seif dunes — which develop in the absence of vegetation and in areas of bidirectional wind regimes — is associated with the transverse dune instability, i.e., the process of disintegration of a transverse dune (which has fixed profile perpendicular to the wind trend) into barchans. The characteristic wavelength of the seif dune meandering is proportional to the dune height, with morphometric relations close to those observed for barchan dunes. By developing simulations with multidirectional wind regimes, we have found that the stabilizing effect of the finite thickness of the atmospheric boundary layer is not necessary to reproduce the growth of accumulating (star) dunes in their initial development stages. Our simulations of dune morphology including multimodal wind systems and low sand availability (low influx) are further relevant to understand dune formation in extra-terrestrial environments, such as on Mars and on Saturn’s moon Titan. We have also shown that the coexistence of fixed and active dunes, observed in many coastal dune fields of the Earth, can be explained by climate-induced cyclic conditions of atmospheric forcing relative to stabilizing vegetation growth. Our simulations of coastal dune fields with saturated sand influx reproduce observed, regional patterns of coexisting fixed and active dunes under seasonal rainfall and wind power. Moreover, we have developed a model for the angle of repose of granular surfaces under various levels of cohesion, and implemented a numerical interface to account for dune migration and sediment transport in surface exposure dating applications. Our simulations show that a vegetated linear dune (VLD) can grow from a sand hill or nebkha under conditions of cyclically varying vegetation growth rate. By removing the vegetation and crust cover from a VLD, the dune surface becomes unstable and gives place to a train of transverse bedforms (surface sand-waves). The size of these transverse bedforms is consistent with observations from a VLD field in NW Negev. Therefore, Earth’s large VLD fields currently stabilized by vegetation cover can give place to active, migrating transverse dunes if vegetation cover in these fields is reduced as a consequence of 21st century climate change. Potential applications include regional modelling the effect of climate-change-driven wind systems on the dynamics of deserts and coastal sediment landscapes, as well as the effectiveness of anti-desertification measures with regard to the wind climate changes predicted for the upcoming decades.

Projektbezogene Publikationen (Auswahl)

• Bidirectional winds, barchan dune asymmetry and formation of seif dunes from barchans: a discussion. Environmental Earth Sciences, 75(18).
  Tsoar, Haim & Parteli, Eric J. R.
  
• Dune formation on the Cooper Creek flood-plain, Strzelecki Desert, Australia - first results of morphodynamic simulations. In Geophysical Research Abstracts, volume 19 (EGU2017), page 7746 (2017)
  M. Kryger, O. Bubenzer, and E. J. R. Parteli
  
• Why do seif dunes meander? In Geophysical Research Abstracts, volume 19 (EGU2017), page 7612 (2017)
  M. Kryger, O. Bubenzer, and E. J. R. Parteli
  
• Dunes on Pluto. Science, 360(6392), 992-997.
  Telfer, Matt W.; Parteli, Eric J. R.; Radebaugh, Jani; Beyer, Ross A.; Bertrand, Tanguy; Forget, François; Nimmo, Francis; Grundy, Will M.; Moore, Jeffrey M.; Stern, S. Alan; Spencer, John; Lauer, Tod R.; Earle, Alissa M.; Binzel, Richard P.; Weaver, Hal A.; Olkin, Cathy B.; Young, Leslie A.; Ennico, Kimberly; Runyon, Kirby; ... & Tyler, Len
  
• Modelling the Retreat of a Coastal Dune under Changing Winds. Journal of Coastal Research, 85, 166-170.
  Gabarrou, Sylvain; Le, Cozannet Gonéri; Parteli, Eric J.R.; Pedreros, Rodrigo; Guerber, Etienne; Millescamps, Bastien; Mallet, Cyril & Oliveros, Carlos
  
• Formation of vegetated linear dunes and their instability under vegetation cover removal: Conceptual model and verification in numerical simulations. In Geophysical Research Abstracts, volume 21 (EGU2019), page 8811 (2019)
  M. Kryger, H. Tsoar, and E. J. R. Parteli
  
• The implications of sampling approach and geomorphological processes for cosmogenic 10Be exposure dating of marine terraces. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 467, 130-139.
  Binnie, A.; Binnie, S.A.; Parteli, E.J.R. & Dunai, T.J.
  
• An expression for the angle of repose of dry cohesive granular materials on Earth and in planetary environments. Proceedings of the National Academy of Sciences, 118(38).
  Elekes, Filip & Parteli, Eric J. R.