In a landmark study published in the Proceedings of the National Academy of Sciences, an international research consortium has fundamentally transformed our understanding of how Earth’s largest sand structures form and develop. The research, led by scientists from China’s Northwest Institute of Eco-Environment and Resources in collaboration with the University of California, Los Angeles and Zhejiang University, demonstrates that topography—not atmospheric constraints or bedrock limitations—serves as the primary determinant in megadune evolution.
The investigation systematically mapped and analyzed megadunes globally—those towering sand formations exceeding 100 meters in height—revealing that over 97% concentrate in the Sahara Desert and arid Asian regions. Through advanced dune simulation modeling, researchers discovered that mountain-proximate locations and depression areas within dune fields create the necessary conditions for massive sand accumulation.
Contrary to previous theories that emphasized atmospheric boundary layer depth or sediment supply limitations, the study demonstrates that abrupt shear stress gradients generated by mountainous and basin-shaped topographies trigger rapid, localized sand accumulation. These topographic features accelerate dune coarsening and megadune growth through enhanced sand flux convergence and increased collision rates among migrating dunes.
The research further explains the scarcity of megadunes in regions like Australia, where vegetation cover limits sediment transport despite otherwise favorable conditions. The findings not only resolve longstanding questions about maximum natural sand accumulation heights but also provide critical insights for studying aeolian processes on extraterrestrial bodies where similar landforms have been observed.