Influence of sand dune geometry on aeolian erosion and dune migration: A wind tunnel study

Sumaja Kolli , Anuj Bind , Pradeep Kumar Dammala , Hassan Hemida

Abstract

Windblown sand disrupts and inundates infrastructure, agricultural farmlands and causes severe environmental impacts. The extent of aeolian erosion is highly influenced by the morphology of sand dunes and wind flow patterns in the vicinity. The current study aims to understand the influence of sand dune geometry on the sand migration and dune evolution system. Wind tunnel experimentation was conducted on three dune geometries of varying stoss slope (32°, 20° and 10°) and identical lee slope (32°). The wind tunnel testing on sand-based dune models revealed the temporal dune evolution patterns that represent the strategic influence of the stoss slope on wind flow around the dunes. Until the threshold friction velocity limit of sand grains, the aeolian erosion measured in terms of soil mass loss (SML, %) was negligible even with an increase in testing duration. However, 20% increase in wind speed from 7.8 to 9.4 m/s increased the SML from 0.05% to 14.23%, 0.46% to 24.51% and 4.76% to 37.24% for 32°, 20° and 10° models, respectively. Further testing at higher wind speed of 10.5 m/s evidenced the formation of shadow dunes along with an increase in SML. The migration pattern from temporal dune evolution concludes that dune with steeper slope offered relatively more resistance to initiation of erosion and migration. However, in the secondary stage of erosion, dune topography varies drastically, and steeper slope is no longer the highly resistant dune. The distinct behavior of 10° stoss slope dune piques interest in current study and relates to the dune process and cyclic evolution of dune systems.

Key Words

aeolian erosion; sand dunes; sand migration; wind tunnel

Address

Sumaja Kolli — 1)Department of Civil Engineering, University of Birmingham, Birmingham B15 2TT, United Kingdom 2)Department of Civil and Infrastructure Engineering, Indian Institute of Technology Jodhpur, Jodhpur 342030, India
Anuj Bind — Department of Civil and Infrastructure Engineering, Indian Institute of Technology Jodhpur, Jodhpur 342030, India
Pradeep Kumar Dammala — Department of Civil and Infrastructure Engineering, Indian Institute of Technology Jodhpur, Jodhpur 342030, India
Hassan Hemida — Department of Civil Engineering, University of Birmingham, Birmingham B15 2TT, United Kingdom

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