Rubjerg Knude - stor klit på vandring

Klitterne ved Rubjerg Knude er dannet i et samspil mellem vindstrømning, stedets specielle geologiske forhold og havets erosion. Udviklingen i løbet af de seneste godt 100 år viser imidlertid, at menneskelige indgreb kan skabe markante ændringer i klitternes udseende i løbet af få år

Rubjerg Knude - stor klit på vandring

Klitterne ved Rubjerg Knude er dannet i et samspil mellem vindstrømning, stedets specielle geologiske forhold og havets erosion. Udviklingen i løbet af de seneste godt 100 år viser imidlertid, at menneskelige indgreb kan skabe markante ændringer i klitternes udseende i løbet af få år

The physics of Aeolian sand transport

International audienceWe give a synthetic overview of the state of art of the physics of sand aeolian transport. We first present the main ideas developed by Bagnold in the middle of the last century. We then review the recent experimental and theoretical advances made in the field and emphasize that the particle flow rate does not exhibit a cubic dependence with the air friction speed, as predicted by Bagnold, but a quadratic one. Finally, we list important open issues that remain

Barchan dune mobility in Mauritania related to dune and interdune sand fluxes

International audience[1] We present a 1 year study of 50 dunes in a small field of barchan dunes in Mauritania. We documented the morphological evolution of the dunes and their migration rates and measured at 10 min intervals the interdune sand transport, the wind strength, and its direction for the same interval of time. The dune heights H0 range between 2 and 5 m, and their celerity c is found to be well approximated by the standard migration law: c = Q0/H0, with Q0 ≈ 50 m3/m yr. From both the interdune sand flux and the migration rate of the dunes we were able to estimate the spatially averaged sand flux at the dune crest as well as the bulk sand flux associated with the mass of sand transported by the dune. We found that the sand flux at the crest was about 3 times greater than the interdune mass transport rate, whereas the bulk sand flux was surprisingly of the same order as the interdune flux. Moreover, we analyzed carefully the interdune sand transport data, which can be well described by the Sorensen law. The cumulative mass of sand transported during moderate wind events within 1 year was much greater than that transported during strong wind events