Title: A Geometric Theory for the origin and motion of sand dunes Show Chinese title

Title: 沙丘的起源和运动的几何理论

Abstract: In this study, a new theory for the spontaneous formation of sand dunes and related bedforms is proposed. The theory is based on the concept that smaller accumulations of sediment outpace larger ones due to differences in surface-to-volume ratio. From this geometric principle, it follows algebraically that for any nonzero bedload transport, the bed (sediment-covered surface) must be tilted upward along the currents direction, forming ripples and dunes. These ideas are validated by making the first-ever accurate predictions of dune speeds (migration rates) that are derived solely from measurements of dune geometries, specifically stoss side (s) and lee face length (l). This prediction has very high statistical significance: R2= 0.92, P = 2.0e-122, n=250. The geometric relationships defined here also predict the backwards migration of antidunes and explain the horned barchan dune and mirrored parabolic dune shapes. Show Chinese abstract

Abstract: 在本研究中，提出了一种关于沙丘和相关床形自发形成的新的理论。 该理论基于这样一个概念，即由于表面积与体积比的差异，较小的沉积物堆积体比较大的堆积体移动得更快。 从这一几何原理出发，代数上可以得出结论：对于任何非零的床载输沙量，床（覆盖有沉积物的表面）必须沿水流方向向上倾斜，形成波纹和沙丘。 这些观点通过首次准确预测沙丘速度（迁移速率）得到验证，这些预测仅基于沙丘几何形状的测量结果，特别是迎流面（s）和背流面长度（l）。 这一预测具有很高的统计显著性：R2= 0.92，P= 2.0e-122，n=250。 此处定义的几何关系还可以预测逆向迁移的反沙丘，并解释角状新月形沙丘和镜像抛物线形沙丘的形状。