Spatial and temporal development of incipient dunes

TL;DR

This study uses four years of lidar data to analyze the formation of incipient dunes, validating linear stability theory's predictions on dune wavelength, growth rate, and propagation velocity in a real-world setting.

Contribution

It provides the first field validation of linear stability analysis predictions for dune formation using long-term lidar data.

Findings

Quantitative agreement between measurements and theory.

Dune wavelength, growth rate, and velocity match predictions.

Theory can be used to infer wind and sediment properties.

Abstract

In zones of loose sand, wind-blown sand dunes emerge due the linear instability of a flat sedimentary bed. This instability has been studied in experiments and numerical models but rarely in the field, due to the large time and length scales involved. We examine dune formation at the upwind margin of the White Sands Dune Field in New Mexico (USA), using 4 years of lidar topographic data to follow the spatial and temporal development of incipient dunes. Data quantify dune wavelength, growth rate, and propagation velocity and also the characteristic length scale associated with the growth process. We show that all these measurements are in quantitative agreement with predictions from linear stability analysis. This validation makes it possible to use the theory to reliably interpret dune-pattern characteristics and provide quantitative constraints on associated wind regimes and sediment properties, where direct local measurements are not available or feasible.